lid. The heat having been briskly urged for a short time, the charcoal

is then removed along with any fresh slag that may have risen, in order to observe whether the vapours have ceased. If not, fresh charcoal must be again applied, the crucible must be covered, and the heat increased, till fumes are no longer produced, and the surface of the silver becomes tranquil. Finally, the alloy, which contains a little gold, and much copper, being now from 11 to 13 _löthig_ (that is, holding from 11 to 13 parts of fine silver in 16 parts), is cast into iron moulds, in ingots of 60 marcs. The loss of weight by evaporation and skimming of the slag amounts to 2 per cent.; the loss in silver is quite inconsiderable.

The dust from the furnace (_tiegelöfen_) is collected in a large condensation chamber of the chimney, and affords from 40 to 50 marcs of silver per cwt. The slags and old crucibles are ground and sent to the small amalgamation mill.

The earthy residuum of the amalgamation casks being submitted to a second amalgamation, affords out of 100 cwts. about 2 lbs. of coarse silver. This is first fused along with three or four per cent. of a mixture of potashes and calcined quicksalz, (impure sulphate of soda), and then refined. The supernatant liquor that is drawn out of the tanks in which the contents of the casks are allowed to settle, consists chiefly of sulphate of soda, along with some common salt, sulphates of iron and manganese, and a little phosphate, arseniate, and fluate of soda. The earthy deposit contains from 1/4 to 9/32 of a _loth_ of silver per cwt., but no economical method of extracting this small quantity has yet been contrived.

The argentiferous or _rich lead_ is treated in Germany by the cupellation furnace represented in _figs._ 1008, 1009, 1010, and 1011. These figures exhibit the cupellation furnace of the principal smelting work in the Hartz, where the following parts must be distinguished; (_fig._ 1010.) 1, masonry of the foundation; 2, flues for the escape of moisture; 3, stone covers of the flues; 4, bed of hard rammed scoriæ; 5, bricks set on edge, to form the permanent area of the furnace; 6, the sole, formed of wood ashes, washed, dried, and beaten down; _k_, dome of iron plate, movable by a crane, and susceptible of being lined two inches thick with loam; _n_, _n_, tuyères for two bellows _s_; having valves suspended before their orifices to break and spread the blast; _q_, door for introducing into the furnace the charge of lead, equal to 84 quintals at a time; _s_, _fig._ 1011., two bellows, like those of a smith’s forge; _y_, door of the fireplace, through which billets of wood are thrown on the grate; _x_, small aperture or door, for giving issue to the frothy scum of the cupellation, and the litharge; _z_, basin of safety, usually covered with a stone slab, over which the litharge falls: in case of accident the basin is laid open to admit the _rich lead_.

The following is the mode of conducting the cupellation. Before putting the lead into the furnace, a floor is made in it of ashes beat carefully down (see 6, _fig._ 1010.); and there is left in the centre of this floor a circular space, somewhat lower than the rest of the hearth, where the silver ought to gather at the end of the operation. The cupel is fully six feet in diameter.

In forming the floor of a cupel, 35 cubic feet of washed wood ashes, usually got from the soap works, are employed. The preparation of the floor requires 2-1/2 hours’ work; and when it is completed, and the movable dome of iron plate has been lined with loam, 84 quintals (cwt.) of lead are laid on the floor, 42 quintals being placed in the part of the furnace farthest from the bellows, and 42 near to the fire-bridge; to these, scoriæ containing lead and silver are added, in order to lose nothing. The movable lid is now luted on the furnace, and heat is slowly applied in the fireplace, by burning fagots of fir-wood, which is gradually raised. Section 1010. is in the line C, D, of 1009.

At the end of three hours, the whole lead being melted, the instant is watched for when no more ebullition can be perceived on the surface of the bath or melted metal; then, but not sooner, the bellows are set a-playing on the surface at the rate of 4 or 5 strokes per minute, to favour the oxidizement.

In five hours, reckoned from the commencement of the process, the fire is smartly raised; when a grayish froth (_abstrich_) is made to issue from the small aperture _x_ of the furnace. This is found to be a brittle mixture of oxidized metals and impurities. The workman now glides the rake over the surface of the bath, so as to draw the froth out of the furnace; and, as it issues, powdered charcoal is strewed upon it, at the aperture _x_, to cause its coagulation. The froth skimming lasts for about an hour and a half.

After this time, the litharge begins to form, and it is also let off by the small opening _x_; its issue being aided by a hook. In proportion as the floor of the furnace gets impregnated with litharge, the workman digs in it a gutter for the escape of the liquid litharge: it falls in front of the small aperture, and concretes in stalactitic forms.

By means of the two movable valves suspended before the tuyères _n_, _n_, (_fig._ 1010.) the workman can direct the blast as he will over the surface of the metal. The wind should be made to cause a slight curl on the liquid, so as to produce circular undulations, and gradually propel a portion of the litharge generated, towards the edges of the cupel, and allow this to retain its shape till the end of the operation. The stream of air should drive the greater part of the litharge towards the small opening _x_, where the workman deepens the outlet for it, in proportion as the level of the metal bath descends, and the bottom of the floor rises by the apposition of the litharge formed. Litharge is thus obtained during about 12 hours; after which period the cake of silver begins to take shape in the centre of the cupel.

Towards the end of the operation, when no more than four additional quintals of litharge can be looked for, and when it forms solely in the neighbourhood of the silver cake in the middle of the floor, great care must be taken to set apart the latter portions, because they contain silver. About this period, the fire is increased, and the workman places before the little opening _x_ a brick, to serve as a mound to the efflux of litharge. The use of this brick is,--1, to hinder the escape of the silver in case of any accident; for example, should an explosion take place in the furnace; 2, to reserve a magazine of litharge, should that still circulating round the silver cake be suddenly absorbed by the cupel, for in this dilemma the litharge must be raked back on the silver; 3, to prevent the escape of the water that must be thrown on the silver at the end of the process.

When the argentiferous litharge, collected in the above small magazine, is to be removed, it is let out in the form of a jet, by the dexterous use of the iron hook.

Lastly, after 20 hours, the silver cake is seen to be well formed, and nearly circular. The moment for stopping the fire and the bellows is indicated by the sudden disappearance of the coloured particles of oxide of lead, which, in the latter moments of oxidation, undulate with extreme rapidity over the slightly convex surface of the silver bath, moving from the centre to the circumference. The phenomenon of their total disappearance is called the _lightning_, or fulguration. Whenever this occurs, the plate of silver being perfectly clean, there is introduced into the furnace, by the door _q_, a wooden spout, along which water, previously heated, is carefully poured on the silver.

The cupellation of 84 quintals of argentiferous lead takes in general 18 or 20 hours’ working. The promptitude of the operation depends on the degree of purity of the leads employed, and on the address of the operator, with whom also lies the economy of fuel. A good workman completes the cupellation of 84 quintals with 300 billets, each equivalent to a cubic foot and eight-tenths of wood (Hartz measure); others consume 400 billets, or more. In general, the cupellation of 100 quintals of lead, executed at the rate of 84 quintal charges, occasions a consumption of 790 cubic feet of resinous wood billets.

The products of the charge are as follow:--

1. Silver, holding in 100 marcs, 7 marcs and 3 loths of alloy 24 to 30 marcs. 2. Pure litharge, containing from 88 to 90 per cent. of lead 50 - 60 quintals. 3. Impure litharge, holding a little silver 2 - 6 -- 4. Skimmings of the cupellation 4 - 8 -- 5. Floor of the furnace impregnated with litharge 22 - 30 --

NOTE.--_The marc is 7 oz. 2 dwts. 4 gr. English troy; and the loth is half an ounce. 16 loths make a marc. 100 pounds Cologne are equal to 103 pounds avoirdupois; and the above quintal contains 116 Cologne pounds._

The loss of lead inevitable by this operation, is estimated at 4 parts in 100. It has been diminished as much as possible in the Frankenscharn works of the Hartz, by leading the smoke into long flues, where the lead fumes are condensed into a metallic soot. The silver cake receives a final purification at the Mint, in a cupel on a smaller scale.

From numerous experiments in the great way, it has been found that not more than 100 quintals of lead can be profitably cupelled at one operation, however large the furnace, and however powerful and multiplied the bellows and tuyères may be; for the loss on either the lead or the silver, or on both, would be increased. In one attempt, no less than 500 quintals were acted on, in a furnace with two fireplaces, and four escapes for the litharge; but the silver remained disseminated through the lead, and the _lightning_ could not be brought on. The chief object in view was economy of fuel.

_Reduction of the Litharge._--This is executed in a slag-hearth, with the aid of wood charcoal.

Such is the train of operations by which the cupriferous galena _schlich_, or ground ore is reduced, in the district of Clausthal, into lead, copper, and silver. The works of Frankenscharn have a front fully 400 feet long.

_Fig._ 1012. exhibits the plan and elevation of these smelting-works, near Clausthal, in the Hartz, for lead ores containing copper and silver, where about 84,000 cwts. of _schlich_ (each of 123 Cologne pounds) are treated every year. This quantity is the produce of 30 distinct mines, as also of nearly as many stamp and preparation works. All these different _schlichs_, which belong to so many different joint-stock companies, are confounded and worked up together in the same series of metallurgic operations; the resulting mixture being considered as one and the same ore belonging to a single undertaking; but in virtue of the order which prevails in this royal establishment, the rights of each of the companies, and consequently of each shareholder, are equitably regulated. A vigorous control is exercised between the mines and the stamps, as also between the stamps and the smelting-houses; while the cost of the metallurgic operations is placed under the officers of the crown, and distributed, upon just principles, among the several mines, according to the quantities of metal furnished by each.

From these arrangements, the following important advantages flow:--

1. The poor ores may be smelted with profit, without putting the companies to any risk or expense in the erection of new works; 2, by the mixture of many different ores, the smelting and metallic product become more easy and abundant; 3, the train of the operations is conducted with all the lights and resources of science; and 4, the amount of metal brought into the market is not subject to such fluctuations as might prove injurious to their sale.

The following is the series of operations:--

1, The fusion of the schlich (sludge); 2, the roasting of the mattes under a shed, and their treatment by four successive re-meltings; 3, the treatment of the resulting black copper; 4, the liquation; 5, the reliquation (_ressuage_); 6, the refining of the copper; 7, the cupellation of the silver; 8, the reduction of the litharge into lead. The 5th and 6th processes are carried on at the smelting works of Altenau.

The buildings are shown at A, B, C, and the impelling stream of water at D; the upper figure being the elevation; the lower, the plan of the works.

_a_, is the melting furnace, with a cylinder bellows behind it; _b_, _c_, _d_, furnaces similar to the preceding, with wooden bellows, such as _fig._ 1013; _e_, is a furnace for the same purpose, with three tuyères, and a cylinder bellows; _f_, the large furnace of fusion, also with three tuyères; _g_, a furnace with seven tuyères, now seldom used; _h_, low furnaces, like the English slag-hearths (_krummofen_), employed for working the last _mattes_; _k_, slag-hearths for reducing the litharge; _m_, the area of the liquation; _n_, _p_, cupellation furnaces.

_x_, _y_, a floor which separates the principal smelting-house into two stories; the materials destined for charging the furnaces being deposited in beds upon the upper floor, to which they are carried by means of two inclined planes, terraced in front of the range of buildings.

Here 89,600 quintals of schlich are annually smelted, which furnish--

Marketable lead 20,907 quintals. Marketable litharge, containing 90 per cent. of lead 7,555 Silver, about 67 Copper (finally purified in the works of Altenau) 35 ------ Total product 28,564

This weight amounts to one twenty-fifth of the weight of ore raised for the service of the establishment. Eight parts of ore furnish, on an average, about one of schlich. The bellows are constructed wholly of wood, without any leather; an improvement made by a bishop of Bamberg, about the year 1620. After receiving different modifications, they were adopted, towards 1730, in almost all the smelting-works of the continent, except in a few places, as Carniola, where local circumstances permitted a water blowing-machine to be erected. These pyramidal shaped bellows, composed of movable wooden boxes, have, however, many imperfections: their size must often be inconveniently large, in order to furnish an adequate stream of air; they do not drive into the furnace all the air which they contain; they require frequent repairs; and, working with great friction, they waste much mechanical power.

_Fig._ 1014. represents such wooden bellows, consisting of two chests or boxes, fitted into each other; the upper or moving one being called the _fly_, the lower or fixed one, the _seat_ (_gite_). In the bottom of the _gite_, there is an orifice furnished with a clack-valve _d_, opening inwards when the _fly_ is raised, and shutting when it falls. In order that the air included in the capacity of the two chests may have no other outlet than the nose-pipe _m_, the upper portion of the _gite_ is provided at its four sides with small square slips of wood _c_, _c_, _c_, which are pressed against the sides of the _fly_ by strong springs of iron wire _b_, _b_, _b_, while they are retained upon the _gite_ by means of small square pieces of wood _a_, _a_, _a_, _a_. The latter _a_, _a_, are perforated in the centre, and adjusted upon rectangular stems, called _buchettes_; they are attached, at their lower ends, to the upright sides of the _gite_ G. P is the driving-shaft of a water-wheel, which, by means of cams or tappets, depresses the fly, while the counterweight Q, _fig._ 1013., raises it again.

_Figs._ 1015, 1016, 1017, 1018. represent the moderately high (_demihauts_, or _half-blast_,) furnaces employed in the works of the lower Hartz, near Goslar, for smelting the silvery lead ores extracted from the mine of Rammelsberg. See its section, in _fig._ 737.

_Fig._ 1015. is the front elevation of the twin furnaces, built in one body of masonry; _fig._ 1016. is a plan taken at the level of the tuyères, in the line _v_, _l_, 6. of _fig._ 1017.; _figs._ 1017. and 1018. exhibit two vertical sections; the former in the line A, B, the latter in the line C, D, of _fig._ 1016. In these four figures the following objects may be distinguished.

_a_, _b_, _c_, _d_, a balcony or platform, which leads to the place of charging _n_; _e_, _f_, wooden stairs, by which the charging workmen mount from the ground _p_, _q_, of the works, to the platform; _g_, _h_, brickwork of the furnaces; _i_, _k_, wall of the smelting-works, against which they are supported; _l_, upper basin of reception, hollowed out of the _brasque_ (or ground charcoal bed) 6; _m_, arch of the tuyère _v_, by which each furnace receives the blast of two bellows; _n_, place of charging, which takes place through the upper orifice _n_, _o_, of the basin _n_, _o_, _v_, _t_, of the furnace; _t_, a slab of clay, placed in such a way that, during the treatment of the lead, a little metallic zinc may run together in a sloping gutter, seen in _fig._ 1001., formed of slates cemented together with clay.

In _figs._ 1015 and 1017., _l_, _z_, is the brickwork of the foundations; _m_, conduits (called evaporatory), for the exhalation of the moisture; 4, a layer of slags, rammed above; 5, a bed of clay, rammed above the slags; 6, a brasque, composed of one part of clay, and two parts of ground charcoal, which forms the sole of the furnace.

The excellent refinery furnace, or _treibheerd_, of Frederickshütte, near Tarnowitz, in Upper Silesia, is represented in _figs._ 1019. and 1020. _a_, is the bottom, made of slag or cinders; _b_, the foundation, of fire-bricks; _c_, the body of the hearth proper, composed of a mixture of 7 parts of dolomite, and 1 of fire-clay, in bulk; _d_, the grate of the air furnace; _e_, the fire-bridge; _f_, the dome or cap, made of iron plate strengthened with bars, and lined with clay-lute, to protect the metal from burning; _g_, the door of the fireplace; _h_, the ash-pit; _i_, the tap-hole; _k_, _k_, the flue, which is divided by partitions into several channels; _l_, the chimney; _m_, a damper-plate for regulating the draught; _n_, a back valve, for admitting air to cool the furnace, and brushes to sweep the flues; _o_, _tuyère_ of copper, which by means of an iron wedge may be sloped more or less towards the hearth; _p_, the _schnepper_, a round piece of sheet iron, hung before the _eye_ of the _tuyère_, to break and spread the blast; _q_, the outlet for the glassy litharge.

Lime-marl has been found to answer well for making the body of the hearth-sole, as it absorbs the vitrified litharge freely, without combining with it. A basin-shaped hollow is formed in the centre, for receiving the silver at the end of the process; and a gutter is made across the hearth for running off the _glätte_ or fluid litharge.

_Figs._ 1021, 1022. represent the eliquation hearth of Neustadt. _Fig._ 1021. is a cross section; _fig._ 1022. is a front view; and _fig._ 1023. a longitudinal section. It is formed by two walls _a_, _a_, 3-1/2 feet high, placed from 1/2 to 1 foot apart, sloped off at top with iron plates, 3 inches thick, and 18 inches broad, called _saigerscharten_, or refining plates, _b_, _b_, inclined 3 inches towards each other in the middle, so as to leave at the lowest point a slit 2-1/2 inches wide between them, through which the lead, as it sweats out by the heat, is allowed to fall into the space between the two walls _c_, called the _saigergasse_ (sweating-gutter). The sole of this channel slopes down towards the front, so that the liquefied metal may run off into a crucible or pot. Upon one of the long sides, and each of the shorter ones, of the hearth, the walls _d_, _d_, are raised two feet high, and upon these the liquation lumps rest; upon the other long side, where there is no wall, there is an opening for admitting these lumps into the hearth. The openings are then shut with a sheet or cast iron plate _e_, which, by means of a chain, pulley, and counterweight, may be easily raised and lowered. _f_, is a passage for increasing the draught of air.

_Figs._ 1024. and 1025. represent the refining furnaces of Frederickshütte by Tarnowitz; _a_, is the fire-door; _b_, the grate; _c_, the door for introducing the silver; _d_, the movable test, resting upon a couple of iron rods _e_, _e_, which are let at their ends into the brickwork. They lie lower than would seem to be necessary; but this is done in order to be able to place the surface of the test at any desired level, by placing tiles _f_, _f_, under it; _g_, the flue, leading to a chimney 18 feet high. For the refining of 100 marks of _blicksilber_, of the fineness of 15-1/2 loths (half ounces) per cwt., 3 cubic feet of pitcoal are required. The test or cupel must be heated before the impure silver and soft lead are put into it.

At these smelting-houses from 150 to 160 cwt. of very pure _workable lead_ (lead containing merely a little silver) are put into the furnace at once, and from 10 to 14 cwt. run off in vitrified oxide; the remainder is then refined with some pure lead, when an alloy containing from 14-1/2 to 15-1/2 loths of blicksilber per cwt. is obtained.

_English refining furnaces._--The refining of lead is well performed in some works in the neighbourhood of Alston-moor, in reverberatory furnaces, _figs._ 1026. and 1027., whose fireplace is 22 inches square, and is separated from the sole by a fire-bridge, 14 inches in breadth. The flame, after having passed over the surface of the lead in the cupel, enters two flues _e_, _e_, on the opposite side of the furnace, which terminate in a chimney _i_, _i_, _i_, _i_, 40 feet high. At the bottom of the chimney are openings _f_, _f_, for taking out the metallic dust deposited within. These openings are shut during the process.

The cupel or test, which constitutes, in fact, the sole of the hearth in which the operation takes place, is movable. It consists of a vertical elliptical ring of iron, A, B, C, D, _figs._ 1028. and 1029., 3-3/4 inches high, the greatest diameter of the ellipse being 4 feet, and the smallest 2-1/2. Four iron bars (A D, _m_, _m´_, B C, _n_, _n´_,) are fixed across its bottom, which are also 3-3/4 inches broad, and an inch thick. The first of these bars is placed 9 inches from the end of the elliptic ring nearest the fireplace, and the three others are equally distributed between this bar and the back end.

In forming the cupel, several layers of a mixture of moistened bone ashes, and fern ashes, in very fine powder, are put into the _test-frame_. The bone ash constitutes from 1/8 to 1/16 of the bulk of the mixture, according to the purity of the fern ashes employed, estimated by the proportion of potash they contain, which has the property of semi-vitrifying the powder of burnt bones, of thus removing its friability, and rendering it more durable. The layers of ashes are strongly beat down, till the frame is entirely filled. The mass thus formed is then hollowed out by means of a little spade, made on purpose, till it is only three quarters of an inch thick above the iron bars near the centre of the bottom. A flange, 2 inches broad, is made at the upper part, and 2-1/2 inches at the lower part, except on the front or _breast_, which is 5 inches thick. In this anterior part, there is hollowed out an opening of an inch and a quarter broad, and 6 inches long, with which the outlet or _gateway_ of the litharge communicates.

The cupel thus prepared is placed in the refining furnace. It rests in an iron ring built into the brickwork. The arched roof of the furnace is 12 inches above the cupel near the fire-bridge, and 9 inches near the flue at the other end.

The tuyère is placed in the back of the furnace, opposite to the side at which the litharge is allowed to overflow.

Openings _g_, _g_, are left at the sides of each cupel, either for running off or for introducing melted lead.

_Refining of lead to extract its silver._--This operation, which the lead of Derbyshire cannot be submitted to with advantage, is performed in a certain number of the smelting-houses at Alston-moor, and always upon leads reduced in the Scotch furnace.

The cupel furnace above described, must be slowly heated, in order to dry the cupel without causing it to crack, which would infallibly be produced by sudden evaporation of the moisture in it. When it has been thus slowly brought to the verge of a red heat, it is almost completely filled with lead previously melted in an iron pot. The cupel may be charged with about 5 cwt. At the temperature at which the lead is introduced, it is immediately covered with a gray pellicle of oxide; but when the heat of the furnace has been progressively raised to the proper pitch, it becomes whitish-red, and has its surface covered over with litharge. Now is the time to set in action the blowing-machine, the blast of which, impelled in the direction of the great axis of the cupel, drives the litharge towards the _breast_ of the cupel, and makes it flow out by the _gateway_ prepared for it, through which it falls upon a cast-iron plate, on a level with the floor of the apartment, and is dispersed into tears. It is carried in this state to the furnace of reduction, and revived. As by the effect of the continual oxidization which it undergoes, the surface of the metal necessarily falls below the level of the gateway of the litharge, melted lead must be added anew by ladling it into the furnace from the iron boiler, as occasion may require. The operation is carried on in this manner till 84 cwt. or 4 Newcastle _fodders_ of lead have been introduced, which takes from 16 to 18 hours, if the tuyère has been properly set. The whole quantity of silver which this mass of lead contains, is left in combination with about 1 cwt. of lead, which, under the name of rich lead, is taken out of the cupel.

When a sufficient number of these pieces of rich lead have been procured, so that by their respective quality, as determined by assaying, they contain in whole from 1000 to 2000 ounces of silver, they are re-melted to extract their silver, in the same furnace, but in a cupel which differs from the former in having at its bottom a depression capable of receiving at the end of the process the cake of silver. In this case a portion of the bottom remains uncovered, on which the scoriæ may be pushed aside with a little rake, from the edges of the silver.

The experiments of MM. Lucas and Gay Lussac have proved that fine silver, exposed to the air in a state of fusion, absorbs oxygen gas, and gives it out again in the act of consolidation. The quantity of oxygen thus absorbed may amount to twenty-two times the volume of the silver. The following phenomena are observed when the mass of metal is considerable; for example, from 40 to 50 pounds.

The solidification commences at the edges, and advances towards the centre. The liquid silver, at the moment of its passage to the solid state, experiences a slight agitation, and then becomes motionless. The surface, after remaining thus tranquil for a little, gets all at once irregularly perturbed, fissures appear in one or several lines, from which flow, in different directions, streams of very fluid silver, which increase the original agitation. The first stage does not yet clearly manifest the presence of gas, and seems to arise from some intestine motion of the particles in their tendency to group, on entering upon the process of crystallization, and thus causing the rupture of the envelop or external crust, and the ejection of some liquid portions.

After remaining some time tranquil, the metal presents a fresh appearance, precisely analogous to volcanic phenomena. As the crystallization continues, the oxygen gas is given out with violence at one or more points, carrying with it melted silver from the interior of the surface, producing a series of cones, generally surmounted by a small crater, vomiting out streams of the metal, which may be seen boiling violently within them.

These cones gradually increase in height by the accumulation of metal thrown up, and that which becomes consolidated on their sloping sides. The thin crust of metal on which they rest, consequently experiences violent impulses, being alternately raised and depressed by such violent agitation, that were it not for the tenacity and elasticity of the metal, there would evidently arise dislocation, fissures, and other analogous accidents. At length several of the craters permanently close, while others continue to allow the gas a passage. The more difficult this is, the more the craters become elevated, and the more their funnels contract by the adhesion or coagulation of a portion of the metal. The projection of globules of silver now becomes more violent; the latter being carried to great distances, even beyond the furnace, and accompanied by a series of explosions, repeated at short intervals. It is generally the last of these little volcanoes that attains the greatest altitude, and exhibits the foregoing phenomena with the greatest energy. It is, moreover, observable, that these cones do not all arise at the same time, some having spent their force, when others commence forming at other points. Some reach the height of an inch, forming bases of two or three inches in diameter. The time occupied by this exhibition is at least from half to three quarters of an hour.

During the formation of these cones, by the evolution of gas, portions of silver are shot forth, which assume, on induration, a form somewhat cylindrical, and often very fantastic, notwithstanding the incompatibility which appears to exist between the fluidity of the silver and these elongated figures. Their appearance is momentary, and without any symptoms of gas, although it is impossible to decide whether they may not arise from its influence; they seem, in fact, to resemble the phenomena of the first volcanic period.

Till very recently the only operations employed for separating silver from lead in the English smelting-works, were the following:--

1. Cupellation, in which the lead was converted into a vitreous oxide, which was floated off from the surface of the silver.

2. Reduction of that oxide, commonly called litharge.

3. Smelting the bottoms of the cupels, to extract the lead which had soaked into them, in a glassy state.

Cupellation and its two complementary operations were, in many respects, objectionable processes; from the injurious effects of the lead vapours upon the health of the workmen; from the very considerable loss of metallic lead, amounting to 7 per cent. at least; and, lastly, from the immense consumption of fuel, as well as from the vast amount of manual labour incurred in such complicated operations. Hence, unless the lead were tolerably rich in silver, it would not bear the expense of cupellation.

The patent process lately introduced by Mr. Pattinson, of Newcastle, is not at all prejudicial to the health of workmen; it does not occasion more than 2 per cent. of loss of lead, and in other respects it is so economical, that it is now profitably applied in Northumberland to alloys too poor in silver to be treated by cupellation. This process is founded upon the following phenomena.

After melting completely an alloy of lead and silver, if we allow it to cool very slowly, continually stirring it meanwhile with a rake, we shall observe at a certain period a continually increasing number of imperfect little crystals, which may be taken out with a drainer, exactly as we may remove the crystals of sea salt deposited during the concentration of brine, or those of sulphate of soda, as its agitated solution cools. On submitting to analysis the metallic crystals thus separated, and also the liquid metal deprived of them, we find the former to be lead almost alone, but the latter to be rich in silver, when compared with the original alloy. The more of the crystalline particles are drained from the metallic bath, the richer does the _mother_ liquid become in silver. In practice, the poor lead is raised by this means to the standard of the ordinary lead of the litharge works; and the better lead is made ten times richer. This very valuable alloy is then submitted to cupellation; but as it contains only a tenth part of the quantity of lead subjected to crystallization, the loss in the cupel will be obviously reduced to one-tenth of what it was by the former process; that is, 7/10 of a per cent., instead of 7.

These nine-tenths of the lead separated by the drainer, are immediately sent into the market, without other loss than the trifling one, of about 1/2 per cent., involved in reviving a little dross skimmed off the surface of the melted metal at the beginning of the operation. Hence the total waste of lead in this method does not exceed 2 per cent. And as only a small quantity of lead requires to be cupelled, this may be done with the utmost slowness and circumspection; whereby loss of the precious metal, and injury to the health of the workpeople, are equally avoided.

The crystallization refinery of Mr. Pattinson is an extremely simple smelting-house. It contains 3 hemispherical cast-iron pans, 41 inches in diameter, and 1/4 of an inch thick. The three pans are built in one straight line, the broad flange at their edge being supported upon brickwork. Each pan has a discharge pipe, proceeding laterally from one side of its bottom, by which the melted metal may be run out when a plug is withdrawn, and each is heated by a small separate fire.

Three tons of the argentiferous lead constitute one charge of each pan; and as soon as it is melted, the fire is withdrawn; the flue, grate-door, and ash-pit, are immediately closed, and made air-tight with bricks and clay-lute. The agitation is now commenced, with a round bar of iron terminated with a chisel point, the workman being instructed merely to keep moving that simple rake constantly in the pan, but more especially towards the edges, where the solidification is apt to begin. He must be careful to take out the crystals, progressively as they appear, with an iron drainer, heated a little higher than the temperature of the metal bath. The liquid metal lifted in the drainer, flows readily back through its perforations, and may be at any rate effectually detached by giving the ladle two or three jogs. The solid portion remains in the form of a spongy, semi-crystalline, semi-pasty mass.

The proportion of crystals separated at each melting, depends upon the original quality of the alloy. If it be poor, it is usually divided in the proportion of two-thirds of poor crystals, and one-third of rich liquid metal; but this proportion is reversed if the alloy contain a good deal of silver.

Let us exemplify, by the common case of a lead containing 10 ounces of silver per ton. Operating upon three tons of this alloy, or 60 cwt., containing 30 oz. of silver, there will be obtained in the first operation--

(_a_) 40 cwt. at 4-1/4 ounces of silver per ton; in whole 9 oz.}30 oz. (_b_) 20 cwt. at 21 -- -- 21 }

Each of these alloys (_a_) and (_b_) will be joined to alloys of like quality obtained in the treatment of one or several other portions of three tons of the primitive alloy. Again, three tons of each of these rich alloys are subjected to the crystallization process, and thus in succession. Thus poorer and poorer lead is got on the one hand, and richer and richer alloys on the other. Sometimes the _mother_ metal is parted from a great body of poor crystals, by opening the discharge-pipe, and running off the liquid, while the workman keeps stirring, to facilitate the separation of the two.

25 fodders, 15 cwts., 49 lbs. = 540 cwts., 49 lbs. of alloy, holding 5 oz. of silver per fodder, in the whole 130 oz., afforded, after three successive crystallizations--

oz. 440 cwts. of poor lead, holding 1/2 oz. of silver per fodder; in all 10-1/2 15 cwt. 49 -- holding the original quantity, nearly 3-1/2 84 cwts. of lead for the cupel, holding 29 oz. 116 ------- Total 130

1 cwt. of loss, principally in the reduction of dross.

The expenses of the new method altogether, including 3_s._ per fodder of patent dues are about one-third of the old; being 17_l._ 13_s._ and 54_l._ 16_s._ respectively, upon 84 cwts. of lead, at 29 oz. per fodder.

In the conditions above stated, the treatment of argentiferous lead occasions the following expenses:--

FOR ONE FODDER. _£_ _s._ _d._ By the new process 0 13 7 old process 2 2 2

Admitting that the treatment of silver holding lead is economically possible only when the profit is equal to one-tenth of the gross expenses of the process, we may easily calculate, with the preceding data, that it is sufficient for the lead to have the following contents in silver:--

With the new process, 3 ounces per fodder; or, 0·000078 With the old process, 8-4/10 ounces per fodder; or, 0·000218

To conclude, the refining by crystallization reduces the cost of the parting of lead and silver, in the proportion of 3 to 1; and allows of extracting silver from a lead which contains only about 3 oz. per ton. In England, the new method produces at present very advantageous results, especially in reference to the great masses to which it may be applied. In 1828, the quantity of lead annually extracted from the mines in the United Kingdom had been progressively raised to 47,000 tons. Reduced almost to one-half of this amount in 1832, by the competition of the mines of la Sierra de Gador, the English production began again to increase in 1833. In 1835, 35,000 tons of lead were obtained, one-half of which only having a mean content of 8-1/2 oz. of silver per ton, was subjected to cupellation, and produced 14,000 oz. of that precious metal. The details of this production are--

Silver extracted from 17,500 tons of lead, } 140,000 oz. holding upon the average 8-1/2 oz. per ton. } Silver extracted from silver ores, properly so called, in Cornwall 36,000 ------- 176,000

In 1837, the production of lead amounted probably to 40,000 tons; upon which the introduction of the new method would have the effect not only of reducing considerably the cost of parting the 20,000 tons of lead containing 8 oz. of silver per ton, but of permitting the extraction of 4 or 5 oz. of silver, which may be supposed to exist upon an average in the greater portion of the remaining 20,000 tons. Otherwise, this mass of the precious metal would have had no value, or have been unproductive.

There are two oxides of silver; called argentic oxide, and suroxide, by Berzelius. 1. The first is obtained by adding solution of caustic potassa, or lime-water, to a solution of nitrate of silver. The precipitate has a brownish-gray colour, which darkens when dried, and contains no combined water. Its specific gravity is 7·143. On exposure to the sun, it gives out a certain quantity of oxygen, and becomes a black powder. This oxide is an energetic base; being slightly soluble in pure water, reacting like the alkalis upon reddened litmus paper, and displacing, from their combinations with the alkalis, a portion of the acids, with which it forms insoluble compounds. It is insoluble in the caustic lyes of potassa or soda. By combination with caustic ammonia, it forms _fulminating silver_. This formidable substance may be prepared by precipitating the nitrate of silver with lime-water, washing the oxide upon a filter, and spreading it upon gray paper, to make it nearly dry. Upon the oxide, still moist, water of ammonia is to be poured, and allowed to remain for several hours. The powder which becomes black, is to be freed from the supernatant liquor by decantation, divided into small portions while moist, and set aside to dry upon bits of porous paper. Fulminating silver may be made more expeditiously by dissolving the nitrate in water of pure ammonia, and precipitating by the addition of caustic potassa lye in slight excess. If fulminating silver be pressed with a hard body in its moist state, it detonates with unparalleled violence; nay, when touched even with a feather, in its dry state, it frequently explodes. As many persons have been seriously wounded, and some have been killed, by these explosions, the utmost precautions should be taken, especially by young chemists, in its preparation. This violent phenomenon is caused by the sudden production of water and nitrogen, at the instant when the metallic oxide is reduced. The quiescent and divellent affinities seem to be so nicely balanced in this curious compound, that the slightest disturbance is sufficient to incite the hydrogen of the ammonia to snatch the oxygen from the silver. The oxide of silver dissolves in glassy fluxes, and renders them yellow. It consists, according to Berzelius, of 93·11 parts of silver, and 6·89 of oxygen. 2. The suroxide of silver is obtained by passing a voltaic current through a weak solution of the nitrate; it being deposited, of course, at the positive or oxygenating pole. It is said to crystallize in needles of a metallic lustre, interlacing one another, which are one-third of an inch long. When thrown into muriatic acid, it causes the disengagement of chlorine, and the formation of chloride of silver; into water of ammonia, it occasions such a rapid production of nitrogen gas, with a hissing sound, as to convert the whole liquid into froth. If a little of it, mixed with phosphorus, be struck with a hammer, a loud detonation ensues. With heat it decrepitates, and becomes metallic silver.

Sulphuret of silver, which exists native, may be readily prepared by fusing the constituents together; and it forms spontaneously upon the surface of silver exposed to the air of inhabited places, or plunged into eggs, especially rotten ones. The tarnish may be easily removed, by rubbing the metal with a solution of _cameleon mineral_, prepared by calcining peroxide of manganese with nitre. Sulphuret of silver is a powerful sulpho-base; since though it be heated to redness in close vessels, it retains the volatile sulphides, whose combinations with the alkalis are decomposed at that temperature. It consists of 87·04 of silver, and 12·96 of oxygen.

A small quantity of tin, alloyed with silver, destroys its ductility. The best method of separating these two metals, is to laminate the alloy into thin plates, and distil them along with corrosive sublimate. The bichloride of tin comes over in vapours, and condenses in the receiver. Silver and lead, when combined, are separated by heat alone in the process of cupellation, as described in the article ASSAY, and in the reduction of silver ores. See _suprà_.

An alloy, containing from one-twelfth to one-tenth of copper, constitutes the silver coin of most nations; being a harder and more durable metal under friction than pure silver. When this alloy is boiled with a solution of cream of tartar and sea-salt, or scrubbed with water of ammonia, the superficial particles of copper are removed, and a surface of fine silver is left.

Chloride of silver is obtained by adding muriatic acid, or any soluble muriate, to a solution of nitrate of silver. A curdy precipitate falls, quite insoluble in water, which being dried and heated to dull redness, fuses into a semi-transparent gray mass, called, from its appearance, _horn-silver_. Chloride of silver dissolves readily in water of ammonia, and crystallizes in proportion as the ammonia evaporates. It is not decomposed by a red heat, even when mixed with calcined charcoal; but when hydrogen or steam is passed over the fused chloride, muriatic acid exhales, and silver remains. When fused along with potassa (or its carbonate), the silver is also revived; while oxygen (or also carbonic acid) gas is liberated, and chloride of potassium is formed. Alkaline solutions do not decompose chloride of silver. When this compound is exposed to light, it suffers a partial decomposition, muriatic acid being disengaged. See ASSAY by the _humid method_.

The best way of reducing the chloride of silver, says Mohr, is to mix it with one-third of its weight of colophony (black rosin), and to heat the mixture moderately in a crucible till the flame ceases to have a greenish-blue colour; then suddenly to increase the fire, so as to melt the metal into an ingot.

The subchloride may be directly formed, by pouring a solution of deuto-chloride of copper or iron upon silver leaf. The metal is speedily changed into black spangles, which, being immediately washed and dried, constitute subchloride of silver. If the contact of the solutions be prolonged, chloride would be formed.

The bromide, cyanide, fluoride, and iodide of silver, have not been applied to any use in the arts. Sulphate of silver may be prepared by boiling sulphuric acid upon the metal. See REFINING OF GOLD AND SILVER. It dissolves in 88 parts of boiling water, but the greater part of the salt crystallizes in small needles, as the solution cools. It consists of 118 parts of oxide, combined with 40 parts of dry acid. Solutions of the hyposulphite of potassa, soda, and lime, which are bitter salts, dissolve chloride of silver, a tasteless substance, into liquids possessed of the most palling sweetness, but not at all of any metallic taste.

The iodide of silver is remarkable, like some other metallic compounds, for changing its colour alternately with heat and cold. If a sheet of white paper be washed over with a solution of nitrate of silver, and afterwards with a somewhat dilute solution of hydriodate of potash, it will immediately assume the pale yellow tint of the cold silver iodide. On placing the paper before the fire, it will change colour from a pale primrose to a gaudy brilliant yellow, like the sun-flower; and on being cooled, it will again resume the primrose hue. These alternations may be repeated indefinitely, like those with the salts of cobalt, provided too great a heat be not applied. The pressure of a finger upon the hot yellow paper makes a white spot, by cooling it quickly.

Fulminate of silver is prepared in the same way as FULMINATE _of Mercury_, which see.

On the 10th of February, 1798, the Lords of the Privy Council appointed the Hon. Charles Cavendish, F. R. S., and Charles Hatchett, Esq., F. R. S., to make investigations upon the wear of gold coin by friction. Their admirable experiments were begun in the latter end of 1798, and completed in April 1801, having been instituted and conducted with every mechanical aid, as devised by these most eminent chemical philosophers, and provided, at no small expense, by the government. The following are the important conclusions of their official report:--[54]

[54] It is inserted in the Philosophical Transactions for 1803.

“Gold made standard by a mixture of equal parts of silver and copper, is not so soft as gold alloyed only with silver; neither is it so pale; for it appears to be less removed from the colour of fine gold, than either the former or the following metal.

“Gold, when alloyed with silver and copper, when annealed, does not become black, but brown; and this colour is more easily removed by the blanching liquor, or solution of alum, than when the whole of the alloy consists of copper. It may also be rolled and stamped with great facility; and, under many circumstances, it appears to suffer less by friction than gold alloyed by silver or copper alone.

“If copper alone forms the alloy, it must be dissolved and separated from the surface of each piece of coin, in the process of annealing and blanching.

“Upon a comparison of the different qualities of the three kinds of standard gold, it appears (strictly speaking) that gold made standard by silver and copper is rather to be preferred for coin.”

It will, undoubtedly, seem not a little strange to the uninitiated, that this report, and its important deductions, should have been of late years entirely set at nought, without any scientific reason or research, apparently for the purpose of giving a certain official in our Mint a good job, in sweating out all the silver from our sovereigns, and replacing it, in the new coinage, with copper, taking on an average 3_d._ worth of silver out of each ounce of our excellent gold coin, and charging the country 6-1/2_d._ for its extraction, besides the very considerable expense in providing fine copper to replace the silver. The pretence set up for this extraordinary degradation of the gold, was, that our coin might peradventure be exported, in order to be de-silvered abroad, a danger which could have been most readily averted, by leaving out as much gold in every sovereign as was equivalent to the silver introduced, and thus preserving its intrinsic value in precious metal. When the film of fine gold which covers each of our present pieces has been rubbed off from the prominent parts, these must appear of a very different and deeper colour than the flat part or ground of the coin. “The reason, therefore, is sufficiently apparent, says Mr. Hatchett, why gold which is alloyed with silver only, cannot be liable to this blemish;” and with one-half of silver alloy, it must be much less liable to it, than with copper alone. Why did the political economists in the recent Committee of the House of Commons on the Mint, blink this question, of public economy and expediency?

Gold, as imported from America, Asia, and Africa, contains on an average nearly the right proportion of silver for making the best coin; and were it alloyed to our national standard, of 22 parts of gold, 1 of silver, and 1 of copper, as defined by Messrs. Cavendish and Hatchett, then by simply adding the deficient quantities of one or two of these metals, by the rule of alligation, the very considerable expense would be saved to the nation, and sulphureous nuisance to the Tower Hamlets, now foolishly incurred in de-silvering and cuprifying sovereigns at the Royal Mint.

It was long imagined in Europe, that the average metallic contents of the silver ores of Mexico and Peru, were considerably greater than those of Saxony and Hungary. Much poorer ores, however, are worked among the Cordilleras than in any part of Europe. The mean product of the whole silver ores that are annually reduced in Mexico, amounts only to from 0·18 to 0·25 of a per cent.; that is, from 3 to 4 ounces in 100 lbs.; the true average being, perhaps, not more than 2-1/2. It is by their greater profusion of ores, not their superior richness, that the mines of South America surpass those of Europe.

GOLD and SILVER produced in Forty Years, from 1790 to 1830.

+------------+------------+--------------+ | | Gold. | Silver. | | +------------+--------------+ |Mexico |_£_6,436,453|_£_139,818,032| |Chile | 2,768,488| 1,822,924| |Buenos Ayres| 4,024,895| 27,182,673| |Russia | 3,703,743| 1,502,981| +------------+------------+--------------+

RETURNS of the DOLLARS coined at the different Mints in MEXICO.

+-----------+----------+----------+----------+----------+ | | 1829. | 1830. | 1831. | 1834. | | +----------+----------+----------+----------+ |Mexico | 1,280,000| 1,090,000| 1,386,000| 952,000| |Guanajuato | 2,406,000| 2,560,000| 2,603,000| 2,703,000| |Zacatecas | 4,505,000| 5,190,000| 4,965,000| 5,527,000| |Guadalaxara| 596,000| 592,000| 590,000| 715,000| |Durango | 659,000| 453,000| 358,000| 1,215,000| |San Luis | 1,613,000| 1,320,000| 1,497,000| 928,000| |Ilalpan | 728,000| 90,000| 323,000| | | +----------+----------+----------+----------+ | Total |11,787,000|11,295,000|11,722,000|12,040,000| +-----------+----------+----------+----------+----------+

The returns for 1832 and 1833 are wanting.

PERU.--RETURNS of GOLD and SILVER coined at the Mints of Lima and Casco.

+-----+-------+---------+------------------+ | | Gold. | Silver. |Total, in Dollars.| | +-------+---------+------------------+ |1830 |180,000|2,015,000| 2,195,000 | |1831 | 92,000|2,384,000| 2,476,000 | |1832 | 94,000|3,210,000| 3,284,000 | |1833 |150,000|2,990,000| 3,140,000 | |1834 |110,000|3,150,000| 3,260,000 | +-----+-------+---------+------------------+

RETURNS of SILVER in BARS produced at the different Smelting-works in PERU.

+----+-------+-------+---------+-------+-------+-------+---------+ | |Lima. |Truxil-|Pasco. |Aya- |Puno. |Are- |Total, in| | | |lo. | |cucho. | |quipa. |Dollars. | | +-------+-------+---------+-------+-------+-------+---------+ |1830|270,000|190,000| 780,000|120,000|250,000|150,000|1,760,000| |1831|270,000| 60,000|1,110,000| 70,000|310,000|110,000|1,930,000| |1832|290,000|100,000|1,800,000| 70,000|345,000| 25,000|2,640,000| |1833|222,000| 70,000|2,130,000| 50,000| 25,000| 65,000|2,562,000| +----+-------+-------+---------+-------+-------+-------+---------+

+----+---------+-------+----------+ | |Coquimbo.|Huasco.| Copiano. | | +---------+-------+----------+ |1831| 785,000|115,000| 670,000 | |1832| 316,000| | 36,000 | |1833| 490,000|100,000| 585,000 | | +---------+-------+----------+ | |1,591,000|215,000|1,291,000 | +----+---------+-------+----------+

SANTIAGO--Mint Coinage.

Gold. Silver. Total. 1832, 174,000; 1833, 392,500 1832, 42,000; 1833, 92,000 700,500

The production of SILVER in the kingdom of SAXONY, amounted to--

59,231 marcs and 8 loths, in the year 1825 55,023 1826 60,034 1827 61,361 1828 65,176 and 10 loths 1830 65,886 1832

The mine of Himmelsfürst alone produces annually 10,000 marcs.

The quantity of SILVER produced in the PRUSSIAN states was--

22,135 marcs in 1825 20,071 1826 18,631 1827 21,731 1828 20,612 1829 20,887 1830 19,031 1831 22,083 1832

The whole annual production of Europe, and Asiatic Russia, has been rated by Humboldt at 292,000 marcs; by other authorities, at 310,000; while at the beginning of the present century, that of the Spanish colonies in America was 3,349,160 marcs, or nearly twelve times as much. The sum total is 3,704,160 marcs, of 3609 grains troy each; which is nearly 1,900,000 lbs. avoirdupois; that is, little less than 9000 tons.

The English Mint silver contains 222 pennyweights of fine silver, and 18 of copper, in the troy pound of 240 pennyweights; or 92·5 in 100 parts. 1 pound troy = 5760 grains, contains 65·8 shillings, each weighing 87·55 grains. The French silver coin contains one-tenth of copper, and a franc weighs 5 grammes = 77·222 grains troy. The Prussian dollar, (_thaler_), is the standard coin; 10-1/2 _thaler_ weigh 1 marc; hence, 1 _thaler_ weighs 343·7 grains troy, and contains 257·9 grains of fine silver; being 75 per cent. of silver, and 25 of alloy. The Austrian coin contains 13/288 of alloy, according to Wasserberg; which is only 4-1/2 per cent.

SILVER LEAF, is made in precisely the same way as GOLD LEAF, to which article I must therefore refer the reader.

SILVERING, is the art of covering the surfaces of bodies with a thin film of silver. When silver leaf is to be applied, the methods prescribed for gold leaf are suitable. Among the metals, copper or brass are those on which the silverer most commonly operates. Iron is seldom silvered; but the processes for both metals are essentially the same.

The principal steps of this operation are the following:--

1. The _smoothing down_ the sharp edges, and polishing the surface of the copper; called _émorfiler_ by the French artists.

2. The _annealing_; or, making the piece to be silvered redhot, and then plunging it in very dilute nitric acid, till it be bright and clean.

3. _Pumicing_; or, clearing up the surface with pumice-stone and water.

4. The _warming_, to such a degree merely as, when it touches water, it may make a slight hissing sound; in which state it is dipped in the very weak aquafortis, whereby it acquires minute insensible asperities, sufficient to retain the silver leaves that are to be applied.

5. The _hatching_. When these small asperities are inadequate for giving due solidity to the silvering, the plane surfaces must be hatched all over with a graving tool; but the chased surfaces need not be touched.

6. The _bluing_, consists in heating the piece till its copper or brass colour changes to blue. In heating, they are placed in hot tools made of iron, called _mandrins_ in France.

7. The _charging_, the workman’s term for silvering. This operation consists in placing the silver leaves on the heated piece, and fixing them to its surface by burnishers of steel, of various forms. The workman begins by applying the leaves double. Should any part darken in the heating, it must be cleared up by the scratch-brush.

The silverer always works two pieces at once; so that he may heat the one, while burnishing the other. After applying two silver leaves, he must heat up the piece to the same degree as at first, and he then fixes on with the burnisher four additional leaves of silver; and he goes on _charging_ in the same way, 4 or 6 leaves at a time, till he has applied, one over another, 30, 40, 50, or 60 leaves, according to the desired solidity of the silvering. He then burnishes down with great pressure and address, till he has given the surface a uniform silvery aspect.

_Silvering by the precipitated chloride of silver._--The white curd obtained by adding a solution of common salt to one of nitrate of silver, is to be well washed and dried. One part of this powder is to be mixed with 3 parts of good pearlash, one of washed whiting, and one and a half of sea salt. After clearing the surface of the brass, it is to be rubbed with a bit of soft leather, or cork moistened with water, and dipped in the above powder. After the silvering, it should be thoroughly washed with water, dried, and immediately varnished. Some use a mixture of 1 part of the silver precipitate, with 10 of cream of tartar, and this mixture also answers very well.

Others give a coating of silver by applying with friction, in the moistened state, a mixture of 1 part of silver-powder precipitated by copper, 2 parts of cream of tartar, and as much common salt. The piece must be immediately washed in tepid water very faintly alkalized, then in slightly warm pure water, and finally wiped dry before the fire. See PLATED MANUFACTURE.

The inferior kinds of plated buttons get their silver coating in the following way:--

2 ounces of chloride of silver are mixed up with 1 ounce of corrosive sublimate, 3 pounds of common salt, and 3 pounds of sulphate of zinc, with water, into a paste. The buttons being cleaned, are smeared over with that mixture, and exposed to a moderate degree of heat, which is eventually raised nearly to redness, so as to expel the mercury from the amalgam, formed by the reaction of the horn silver and the corrosive sublimate. The copper button thus acquires a silvery surface, which is brightened by clearing and burnishing.

Leather is silvered by applying a coat of parchment size, or spirit varnish, to the surface, and then the silver leaf, with pressure.

SIMILOR, is a golden-coloured variety of brass.

SINGEING OF WEBS. The old furnace for singeing cotton goods is represented in longitudinal section, _fig._ 1030., and in a transverse one in _fig._ 1031. _a_ is the fire-door; _b_, the grate; _c_, the ash-pit; _d_, a flue, 6 inches broad, and 2-1/2 high, over which a hollow semi-cylindrical mass of cast iron _e_, is laid, one inch thick at the sides, and 2-1/2 thick at the top curvature. The flame passes along the fire-flue _d_, into a side opening _f_, in the chimney. The goods are swept swiftly over this ignited piece of iron, with considerable friction, by means of a wooden roller, and a swing frame for raising them at any moment out of contact.

In some shops, semi-cylinders of copper, three quarters of an inch thick, have been substituted for those of iron, in singeing goods prior to bleaching them. The former last three months, and do 1500 pieces with one ton of coal; while the latter, which are an inch and a half thick, wear out in a week, and do no more than from 500 to 600 pieces with the same weight of fuel.

In the early part of the year 1818, Mr. Samuel Hall enrolled the specification of a patent for removing the downy fibres of the cotton thread from the interstices of bobbin-net lace, or muslins, which he effected by singeing the lace with the flame of a gas-burner. The second patent granted to Mr. Hall, in April, 1823, is for an improvement in the above process; viz., causing a strong current of air to draw the flame of the gas through the interstices of the lace, as it passes over the burner, by means of an aperture in a tube placed immediately above the row of gas-jets, which tube communicates with an air-pump or exhauster.

_Fig._ 1032. shows the construction of the apparatus complete, and manner in which it operates; _a_, _a_, is a gas-pipe, supplied by an ordinary gasometer; from this pipe, several small ones extend upwards to the long burner _b_, _b_. This burner is a horizontal tube, perforated with many small holes on the upper side, through which, as jets, the gas passes; and when it is ignited, the bobbin-net lace, or other material intended to be singed, is extended and drawn rapidly over the flame, by means of rollers, which are not shown in the figure.

The simple burning of the gas, even with a draught chimney, as in the former specification, is found not to be at all times efficacious; the patentee, therefore, now introduces a hollow tube _c_, _c_, with a slit or opening, immediately over the row of burners; and this tube, by means of the pipes _d_, _d_, _d_, communicates with the pipe _e_, _e_, _e_, which leads to the exhausting apparatus.

This exhausting apparatus consists of two tanks, _f_ and _g_, nearly filled with water, and two inverted boxes or vessels, _h_ and _i_, which are suspended by rods to the vibrating beam _k_; each of the boxes is furnished with a valve opening upwards; _l_, _l_, are pipes extending from the horizontal part of the pipe _e_, up into the boxes or vessels _h_ and _i_, which pipes have valves at their tops, also opening upward. When the vessel _h_ descends, the water in the tank forces out the air contained within the vessel at the valve _m_; but when that vessel rises again, the valve _m_ being closed, the air is drawn from the pipe _e_, through the pipe _l_. The same takes place in the vessel _i_, from which the air in its descent is expelled through the valve _n_, and, in its ascent, draws the air through the pipe _l_, from the pipe _e_. By these means, a partial exhaustion is effected in the pipe _e_, _e_, and the tube _c_, _c_; to supply which, the air rushes with considerable force through the long opening of the tube _c_, _c_, and carries with it the flame of the gas-burners. The bobbin-net lace, or other goods, being now drawn over the flame between the burner _b_, _b_, and the exhausted tube _c_, _c_, by means of rollers, as above said, the flame of the gas is forced through the interstices of the fabric, and all the fine filaments and loose fibres of the thread are burnt off, without damaging the substance of the goods.

To adjust the draught from the gas-burners, there are stopcocks introduced into several of the pipes _d_; and to regulate the action of the exhausting apparatus, an air vessel _o_, is suspended by a cord or chain passing over pulleys, and balanced by a weight _p_. There is also a scraper introduced into the tube _c_, which is made, by any convenient contrivance, to revolve and slide backwards and forwards, for the purpose of removing any light matter that may arise from the goods singed, and which would otherwise obstruct the air passage. Two of these draught tubes _c_, may be adapted and united to the exhausting apparatus, when a double row of burners is employed, and the inclination of the flame may be directed upwards, downwards, or sideways, according to the position of the slit in the draft tube, by which means any description of goods may, if required, be singed on both sides at one operation.

The greater part of the bobbin-net lace made in England, is sent to Mr. Hall’s works, at Basford, near Nottingham, to be singed; and at a reduction of price truly wonderful. He receives now only one farthing for what he originally was paid one shilling.

SKIN (_Peau_, Fr.; _Haut_, Germ.); the external membrane of animal bodies, consists of three layers: 1. the epidermis, scarf-skin, (_Oberhaut_, Germ.); 2. the vascular organ, or papillary body, which performs the secretions; and 3. the true skin, (_Lederhaut_, Germ.), of which leather is made. The skin proper, or dermoid substance, is a tissue of innumerable very delicate fibres, crossing each other in every possible direction, with small orifices between them, which are larger on its internal than on its external surface. The conical channels thus produced, are not straight, but oblique, and filled with cellular membrane; they receive vessels and nerves which pass out through the skin (_cutis vera_), and are distributed upon the secretory organ. The fibrous texture of the skin is composed of the same animal matter as the serous membranes, the cartilages, and the cellular tissue; the whole possessing the property of dissolving in boiling water, and being, thereby, converted into glue. See GLUE, LEATHER, and TAN.

SLAG (_Laitier_, Fr.; _Schlacke_, Germ.); is the vitreous mass which covers the fused metals in the smelting-hearths. In the iron-works it is commonly called _cinder_. Slags consist, in general, of bi-silicates of lime and magnesia, along with the oxides of iron and other metals; being analogous in composition, and having the same crystalline form as the mineral, _pyroxene_. See COPPER and IRON.

SLATES (_Ardoises_, Fr.: _Schiefern_, Germ.) The substances belonging to this class may be distributed into the following species:--

1. Mica-slate, occasionally used for covering houses. 2. Clay-slate, the proper roofing-slate. 3. Whet-slate. 4. Polishing-slate. 5. Drawing-slate, or black chalk. 6. Adhesive slate. 7. Bituminous shale. 8. Slate-clay.

1. _Mica-slate._--This is a mountain rock of vast continuity and extent, of a schistose texture, composed of the minerals mica and quartz, the mica being generally predominant.

2. _Clay-slate._--This substance is closely connected with mica; so that uninterrupted transitions may be found between these two rocks in many mountain chains. It is a simple schistose mass, of a bluish-gray or grayish-black colour, of various shades, and a shining, somewhat pearly internal lustre on the faces, but of a dead colour in the cross fracture.

Clay-slate is extensively distributed in Great Britain. It skirts the Highlands of Scotland, from Lochlomond by Callender, Comrie, and Dunkeld; resting on, and gradually passing into mica-slate throughout the whole of that territory. Roofing-slate occurs, on the western side of England, in the counties of Cornwall and Devon; in various parts of North Wales and Anglesea; in the north-east parts of Yorkshire, near Ingleton, and in Swaledale; as also in the counties of Cumberland and Westmorland. It is likewise met with in the county of Wicklow and other mountainous districts of Ireland.

All the best beds of roofing-slate improve in quality as they lie deeper under the surface; near to which, indeed, they have little value.

A good roofing-slate should split readily into thin even laminæ; it should not be absorbent of water either on its face or endwise, a property evinced by its not increasing perceptibly in weight after immersion in water; and it should be sound, compact, and not apt to disintegrate in the air. The slate raised at Eisdale, on the west coast of Argyllshire, is very durable.

_Cleaving and dressing of the slates._--The splitter begins by dividing the block, cut lengthwise, to a proper size, which he rests on end, and steadies between his knees. He uses a mallet and a chisel, which he introduces into the stone in a direction parallel to the _folia_. By this means he reduces it into several manageable pieces, and he gives to each the requisite length, by cutting cross grooves on the flat face, and then striking the slab with the chisel. It is afterwards split into thinner sections, by finer chisels dexterously applied to the edges. The slate is then dressed to the proper shape, by being laid on a block of wood, and having its projecting parts at the ends and sides cut off with a species of hatchet or chopping-knife. It deserves to be noticed, that blocks of slate may lose their property of divisibility into thin laminæ. This happens from long exposure to the air, after they have been quarried. The workmen say, then, that they have lost their waters. For this reason, the number of splitters ought to be always proportioned to the number of block-hewers. Frost renders the blocks more fissile; but a supervening thaw renders them quite refractory. A new frost restores the faculty of splitting, though not to the same degree; and the workmen therefore avail themselves of it without delay. A succession of frosts and thaws renders the quarried blocks quite intractable.

3. _Whet-slate, or Turkey hone_, is a slaty rock, containing a great proportion of quartz, in which the component particles, the same as in clay-slate and mica-slate, but in different proportions, are so very small as to be indiscernible.

4. _Polishing slate._ Colour, cream-yellow, in alternate stripes; massive; composition impalpable; principal fracture, slaty, thin, and straight; cross fracture, fine earthy; feels fine, but meagre; adheres little, if at all, to the tongue; is very soft, passing into friable; specific gravity in the dry state, 0·6; when imbued with moisture, 1·9. It is supposed to have been formed from the ashes of burnt coal. It is found at Planitz, near Zwickau, and at Kutschlin near Bilin in Bohemia.

5. _Drawing-slate, or black chalk_; has a grayish-black colour; is very soft, sectile, easily broken, and adheres slightly to the tongue; spec. grav. 2·11. The streak is glistening. It occurs in beds in primitive and transition clay-slate; also in secondary formations, as in the coal-measures of most countries. It is used in crayon drawing. Its trace upon paper is regular and black. The best kinds are found in Spain, Italy, and France. Some good black chalk occurs also in Caernarvonshire and in the island of Islay.

6. _Adhesive slate_, has a light greenish-gray colour, is easily broken or exfoliated, has a shining streak, adheres strongly to the tongue, and absorbs water rapidly, with the emission of air-bubbles and a crackling sound.

7. _Bituminous shale_, is a species of soft, sectile slate-clay, much impregnated with bitumen, which occurs in the coal-measures.

8. _Slate-clay_, has a gray or grayish-yellow colour; is massive, with a dull glimmering lustre from spangles of mica interspersed. Its slaty fracture approaches at times to earthy; fragments, tabular; soft, sectile, and very frangible; specific gravity, 2·6. It adheres to the tongue, and crumbles down when immersed for some time in water. It is found as an alternating bed in the coal-measures. (See the sections of the strata under PITCOAL.) When breathed upon, it emits a strong argillaceous odour. When free from lime and iron, it forms an excellent material for making refractory fire-bricks, being an infusible compound of alumina and silica; one of the best examples of which is the schist known by the name of Stourbridge clay.

SMALL WARES, is the name given in this country to textile articles of the tape kind, narrow bindings of cotton, linen, silk, or woollen fabric; plaited sash cord, braid, &c. Tapes are woven upon a loom like that for weaving ribbons, which is now generally driven by mechanical power. Messrs. Worthington and Mulliner obtained a patent, in June, 1825, for improvements in such a loom, which have answered the purposes of their large factory in Manchester very well; and in May, 1831, Mr. Whitehead, of the same town, patented certain improvements in the manufacture of small wares. The objects of the latter patent are, the regular taking up of the tape or cloth, as it is woven, a greater facility of varying the vibration of the lay, together with the saving of room required for a range of looms to stand in.[55] See BRAIDING MACHINE.

[55] Newton’s London Journal, vol. xiii. p. 192; and vol. i. combined series, p. 212.

SMALT, see AZURE and COBALT.

Imported for home consumption in 1834, 162,232 lbs.; in 1835, 96,649; in 1836, 79,531; duty, 4_d._ per lb.

SMELTING, is the operation by which the ores of iron, copper, lead, &c., are reduced to the metallic state. See METALLURGY, ORES, and the respective metals.

SOAP (_Savon_, Fr.; _Seife_, Germ.); is a chemical compound, of saponified fats or oils with potash or soda, prepared for the purposes of washing linen, &c. Fatty matters, when subjected to the action of alkaline lyes, undergo a remarkable change, being converted into three different acids, called stearic, margaric, and oleic; and it is these acids, in fact, which combine with the bases, in definite proportions, to form compounds analogous to the neutro-saline. Some chemical writers describe under the title soap, every compound which may result from the union of fats with the various earths and metallic oxides--a latitude of nomenclature which common language cannot recognise, and which would perplex the manufacturer.

Soaps are distinguished into two great classes, according to their consistence; the hard and the soft; the former being produced by the action of soda upon fats, the latter by that of potash. The nature of the fats contributes also somewhat to the consistence of soaps; thus tallow, which contains much stearine and margarine, forms with potash a more consistent soap than liquid oils will do, which consist chiefly of oleine. The drying oils, such as those of linseed and poppy, produce the softest soaps.

1. _Of the manufacture of hard soap._--The fat of this soap, in the northern countries of Europe, is usually tallow, and in the southern, coarse olive oil. Different species of grease are saponified by soda, with different degrees of facility; among oils, the olive, sweet almond, rapeseed, and castor oil; and among solid fats, tallow, bone grease, and butter, are most easily saponified. According to the practice of the United Kingdom, six or seven days are required to complete the formation of a pan of hard soap, and a day or two more for settling the impurities, if it contains rosin. From 12 to 13 cwt. of tallow are estimated to produce one ton of good soap. Some years ago, in many manufactories the tallow used to be saponified with potash lyes, and the resulting soft soap was converted, in the course of the process, into hard soap, by the introduction of muriate of soda, or weak kelp lyes, in sufficient quantity to furnish the proper quantity of soda by the reaction of the potash upon the neutral salts. But the high price of potash, and the diminished price as well improved quality of the crude sodas, have led to their general adoption in soap-works. The soda-ash used by the soap-boiler, contains in general about 36 per cent. of real soda, in the state of dry carbonate, mixed with muriate of soda, and more or less undecomposed sulphate. I have met lately with soda-ash, made from sulphate of soda, in which the materials had been so ill worked, and so imperfectly decomposed, as to contain 16 per cent. of sulphate, a circumstance equally disgraceful, as it was ruinous to the soda manufacturer. The barillas from Spain and Teneriffe contain from 18 to 24 per cent. of real soda. The alkali in both states is employed in England; barilla being supposed by many to yield a finer white or curd soap, on account of its freedom from sulphur.

The crude soda of either kind being ground, is to be stratified with lime in cylindrical cast-iron vats, from 6 to 7 feet wide, and from 4 to 5 feet deep; the lowest layer consisting, of course, of unslaked or shell quicklime. The vats have a false bottom, perforated with holes, and a lateral tubulure under it, closed commonly with a wooden plug, similar to the _épine_ of the French soap pans, by which the lyes trickle off clear and caustic, after infiltration through the beds of lime. The quantity of lime must be proportional to the carbonic acid in the soda.

Upon 1 ton of tallow put into the soap pan, about 200 gallons of soda lye, of specific gravity 1·040, being poured, heat is applied, and after a very gentle ebullition of about 4 hours, the fat will be found to be completely saponified, by the test of the spatula, trowel, or pallet knife; for the fluid lye will be seen to separate at once upon the steel blade, from the soapy paste. Such lyes, if composed of pure caustic soda, would contain 4 per cent. of alkali; but from the presence of neutro-saline matter, they seldom contain so much as 2 per cent.; in fact, a gallon may be estimated to contain not more than 2 ounces; so that 200 gallons contain 25 pounds of real soda. The fire being withdrawn from the soap pan, the mass is allowed to cool during one hour, or a little more, after which the spent lyes, which are not at all alkaline, are run off by a spigot below, or pumped off above, by a pump set into the pan. A second similar charge of lye is now introduced into the pan, and a similar boiling process is renewed. Three such boils may be given in the course of one day’s work, by an active soap-maker. Next day the same routine is resumed with somewhat stronger lyes, and so progressively, till, towards the sixth day, the lye may have the density of 1·160, and will be found to contain 6 per cent. of real soda.[56] Were the lye a solution of pure caustic soda, it would contain at this density no less than 14-3/4 per cent. of alkali. The neutro-saline matter present in the spent lye is essential to the proper granulation and separation of the saponaceous compound; for otherwise the watery menstruum would dilute and even liquefy the soap. Supposing 12-1/2 cwt. of tallow to yield upon an average 20 cwt. of hard soap, then 20 cwt. of tallow will produce 32 cwt.; and as its average contents in soda are 6 per cent., these 32 cwt. should require 1·52 cwt. of real soda for their production. If barilla at 20 per cent. be the alkali employed, then 7·6 cwt. of barilla must be consumed in the said process. If the alkali be soda-ash of 40 per cent., half the weight will of course suffice. I have reason to believe that there is great waste of alkali incurred in many soap-works, as 6 cwt. of soda-ash, of at least 30 per cent., is often expended in making 1 ton of soap, being 50 per cent. more than really enters into the composition of the soap.

[56] According to my own experiments upon the soda lye used in the London soap-works.

The barillas always contain a small proportion of potash, to which their peculiar value, in making a less brittle or more plastic hard soap than the factitious sodas, may with great probability be ascribed. Chemistry affords many analogies, especially in mineral waters, where salts, apparently incompatible, co-exist in dilute solutions. We may thus conceive how a small quantity of stearate or oleate of potash may resist the decomposing action of the soda salts. The same modification of the consistence of hard soap may, however, be always more conveniently produced by a proper admixture of oleine with stearine.

Soda which contains sulphurets is preferred for making the mottled or marbled soap, whereas the desulphuretted soda makes the best white curd soap. Mottling is usually given in the London soap-works, by introducing into the nearly finished soap in the pan a certain quantity of the strong lye of crude soda, through the rose spout of a watering-can. The dense sulphuretted liquor, in descending through the pasty mass, causes the marbled appearance. In France a small quantity of solution of sulphate of iron is added during the boiling of the soap, or rather with the first service of the lyes. The alkali seizes the acid of the sulphate, and sets the protoxide of iron free, to mingle with the paste, to absorb more or less oxygen, and to produce thereby a variety of tints. A portion of oxide combines also with the stearine to form a metallic soap. When the oxide passes into the red state, it gives the tint called _manteau Isabelle_. As soon as the _mottler_ has broken the paste, and made it pervious in all directions, he ceases to push his rake from right to left, but only plunges it perpendicularly, till he reaches the lye; then he raises it suddenly in a vertical line, making it act like the stroke of a piston in a pump, whereby he lifts some of the lye, and spreads it over the surface of the paste. In its subsequent descent through the numerous fissures and channels, on its way to the bottom of the pan, the coloured lye impregnates the soapy particles in various forms and degrees, whence a varied marbling results.

Three pounds of olive oil afford five pounds of marbled Marseilles soap of good quality, and only four pounds four ounces of white soap; showing that more water is retained by the former than the latter. Oil of grains, as linseed and rapeseed, do not afford so solid a soda soap as oil of olives; but tallow affords a still harder soap with soda. Some of the best Windsor soap made in London contains one part of olive oil (gallipoli) for every nine parts of tallow. Much of the English hard soap is made with kitchen and bone fat, of a very coarse quality; the washing of the numerous successive lyes, however, purifies the foul fats, and deprives them of their offensive smell in a great degree. It is common now at Marseilles to mix ten per cent. of the oil of grains with olive oil; for which purpose a large proportion of the oils extracted from seeds in the mills of the _Department du Nord_ is sent to Marseilles; but five per cent. of poppy-seed oil, mixed with tallow, renders the soap made with the mixture stringy and unfit for washing; because the two species of fat refuse to amalgamate.

The affinity between the stearine of tallow and the alkali, is so great that a soap may be speedily made from them in the cold. If we melt tallow at the lowest possible temperature, and let it cool to the fixing point, then add to it half its weight of caustic lye, at 36° B., agitating meanwhile incessantly with a pallet knife, we shall perceive, at the end of some hours of contact, the mixture suddenly acquire a very solid consistence, and at the same moment assume a marked elevation of temperature, proving the phenomenon to be due to chemical attraction. In some trials of this kind, the thermometer has risen from 54° to 140° F.

According to recent experiments made in Marseilles, 100 pounds of olive oil take, for their conversion into soap, 54 pounds of crude soda, of 36 per cent. alkaline strength. One part of lime is employed for rendering three parts of the soda caustic. The richer the oil is in stearine, the more dilute should be the lye used in the saponification; and _vice versâ_ when it abounds in oleine. For oil of the former kind, the first lyes added have a density of from 8° to 9° B.; but for the latter kind, the density is from 10° to 11°. When four parts of olive oil are mixed with one part of poppy, rape, or linseed oil, as is now the general practice at Marseilles, then for such a mixture the first lyes have usually a specific gravity of from 20° to 25°, the second from 10° to 15°, and the third from 4° to 5°, constituting a great difference from the practice in Great Britain, where the weaker lyes are generally employed at the commencement. The chief reason for this practice is, however, to be found in the more complete causticity of the weak than of the strong lyes, according to the slovenly way in which most of our soap-boilers prepare them. Indeed, one very extensive manufacturer of soap in London assured me that the lyes should not be caustic; an extraordinary assertion, upon which no comment need be made. In common cases, I would recommend the first combination of the ingredients to be made with somewhat weak, but perfectly caustic lye, and when the saponification is fairly established, to introduce the stronger lye.

In a Marseilles soap-house, there are four lye-vats in each set: No. 1. is the _fresh vat_, into which the fresh alkali and lime are introduced; No. 2. is called the _avançaire_, being one step in advance; No. 3. is the small _avançaire_, being two steps in advance, and therefore containing _weaker_ liquor; No. 4. is called the _water_ vat, because it receives the water directly.

Into No. 3. the moderately exhausted or somewhat spent lyes are thrown. From No. 3. the lye is run or pumped into No. 2., to be strengthened; and in like manner from No. 3. into No. 1. Upon the lime paste in No. 4., which has been taken from No. 3., water is poured; the lye thus obtained is poured upon the paste of No. 3., which has been taken from No. 2. No. 3. is twice lixiviated; and No. 2., once. The receiver under No. 1. has four compartments; into No. 1. of which the first and strongest lye is run; into No. 2. the second lye; into No. 3. the third lye; and into No. 4. the fourth lye, which is so weak as to be used for lixiviation, instead of water; (_pour d’avances_).

The lime of vat No. 4., when exhausted, is emptied out of the window near to which it stands; in which case the water is poured upon the contents of No. 3.; and upon No. 2. the somewhat spent lyes.

No. 1. is now the _avançaire_ of No. 4; because this has become, in its turn, the _fresh_ vat, into which the fresh soda and quicklime are put. The lye discharged from No. 3. comes, in this case, upon No. 2.; and after being run through it, is thrown upon No. 1.

144 pounds of oil yield at Marseilles, upon an average, not more than from 240 to 244 pounds of soap; or 100 pounds yield about 168; so that in making 100 pounds of soap, at this rate nearly 60 pounds of oil are consumed.

OF YELLOW OR ROSIN SOAP.

Rosin, although very soluble in alkaline menstrua, is not however susceptible, like fats, of being transformed into an acid, and will not of course saponify, or form a proper soap by itself. The more caustic the alkali, the less consistence has the resinous compound which is made with it. Hence fat of some kind, in considerable proportion, must be used along with the rosin, the _minimum_ being equal parts; and then the soap is far from being good. As alkaline matter cannot be neutralized by rosin, it preserves its peculiar acrimony in a soap poor in fat, and is ready to act too powerfully upon woollen and all other animal fibres to which it is applied. It is said that rancid tallow serves to mask the strong odour of rosin in soap, more than any oil or other species of fat. From what we have just said, it is obviously needless to make the rosin used for yellow soaps pass through all the stages of the saponifying process; nor would this indeed be proper, as a portion of the rosin would be carried away, and wasted with the spent lyes. The best mode of proceeding, therefore, is first of all to make the hard soap in the usual manner, and at the last service or charge of lye, namely, when this ceases to be absorbed, and preserves in the boiling-pan its entire causticity, to add the proportion of rosin intended for the soap. In order to facilitate the solution of the rosin in the soap, it should be reduced to coarse powder, and well incorporated by stirring with the rake. The proportion of rosin is usually from one-third to one-fourth the weight of the tallow. The boil must be kept up for some time with an excess of caustic lye; and when the paste is found, on cooling a sample of it, to acquire a solid consistence, and when diffused in a little water, not to leave a resinous varnish on the skin, we may consider the soap to be finished. We next proceed to draw off the superfluous lyes, and to purify the paste. For this purpose, a quantity of lyes at 80° B. being poured in, the mass is heated, worked well with a rake, then allowed to settle, and drained of its lyes. A second service of lyes, at 4° B., is now introduced, and finally one at 2°; after each of which, there is the usual agitation and period of repose. The pan being now skimmed, and the scum removed for another operation, the soap is laded off by hand-pails into its frame-moulds. A little palm oil is usually employed in the manufacture of yellow soap, in order to correct the flavour of the rosin, and brighten the colour. This soap, when well made, ought to be of a fine wax-yellow hue, be transparent upon the edges of the bars, dissolve readily in water, and afford, even with hard pump-water, an excellent lather.

The frame-moulds for hard soap are composed of strong wooden bars, made into the form of a parallelogram, which are piled over each other, and bound together by screwed iron rods, that pass down through them. A square well is thus formed, which in large soap factories is sometimes 10 feet deep, and capable of containing a couple of tons of soap.

Mr. Sheridan some time since obtained a patent for combining silicate of soda with hard soap, by triturating them together in the hot and pasty state with a crutch in an iron pan. In this way from 10 to 30 per cent. of the silicate may be introduced. Such soap possesses very powerful detergent qualities, but it is apt to feel hard and be somewhat gritty in use. The silicated soda is prepared by boiling ground flints in a strong caustic lye, till the specific gravity of the compound rises to nearly double the density of water. It then contains about 35 grains of silica, and 46 of soda-hydrate, in 100 grains[57].

[57] By my own experiments upon the liquid silicate made at Mr. Gibbs’ excellent soap factory.

Hard soap, after remaining two days in the frames, is at first divided horizontally into parallel tablets, 3 or 4 inches thick, by a brass wire; and these tablets are again cut vertically into oblong nearly square bars, called wedges in Scotland.

The soap-pans used in the United Kingdom are made of cast iron, and in three separate pieces joined together by iron-rust cement. The following is their general form:--The two upper frusta of cones are called curbs; the third, or undermost, is the pan, to which alone the heat is applied, and which, if it gets cracked in the course of boiling, may easily be lifted up within the conical pieces, by attaching chains or cords for raising it, without disturbing the masonry, in which the curbs are firmly set. The surface of the hemispherical pan at the bottom, is in general about one-tenth part of the surface of the conical sides.

The white ordinary tallow soap of the London manufacturers, called curd soap, consists, by my experiments, of--fat, 52; soda, 6; water, 42; = 100. Nine-tenths of the fat, at least, is tallow.

I have examined several other soaps, and have found their composition somewhat different.

The foreign Castile soap of the apothecary has a specific gravity of 1·0705, and consists of--

Soda 9 Oily fat 76·5 Water and colouring-matter 14·5 ----- 100·0

English imitation of Castile soap, spec. grav. 0·9669, consists of--

Soda 10·5 Pasty-consistenced fat 75·2 Water, with a little colouring-matter 14·3 ----- 100·0

A perfumer’s white soap was found to consist of--

Soda 9 Fatty matter 75 Water 16 --- 100

Glasgow white soap--

Soda 6·4 Tallow 60·0 Water 33·6 ----- 100·0

Glasgow brown rosin soap--

Soda 6·5 Fat and rosin 70·0 Water 23·5 ----- 100·0

A London cocoa-nut oil soap was found to consist of--

Soda 4·5 Cocoa-nut lard 22·0 Water 73·5 ----- 100·0

This remarkable soap was sufficiently solid; but it dissolved in hot water with extreme facility. It is called marine soap, because it washes linen with sea water.

A poppy-nut-oil hard soap consisted of--

Soda 7 Oil 76 Water 17 --- 100[58]

[58] My own experiments. See Fats, Oils, and Stearine.

The soap known in France by the name of _soap in tables_ consists, according to M. Thenard’s analysis, of--

Soda 4·6 Fatty matter 50·2 Water 45·2 ----- 100·0

M. D’Arcet states the analysis of Marseilles soap at--

Soda 6 Oil 60 Water 34 --- 100

SOFT SOAP.

The principal difference between soaps with base of soda, and soaps with base of potash, depends upon their mode of combination with water. The former absorb a large quantity of it, and become solid; they are chemical hydrates. The others experience a much feebler cohesive attraction; but they retain much more water in a state of mere mixture.

Three parts of fat afford, in general, fully five parts of soda soap, well dried in the open air; but three parts of fat or oil will afford from six to seven parts of potash soap of moderate consistence. This feebler cohesive force renders it apt to deliquesce, especially if there be a small excess of the alkali. It is, therefore, impossible to separate it from the lyes; and the washing or _relargage_, practised on the hard-soap process, is inadmissible in the soft. Perhaps, however, this concentration or abstraction of water might be effected by using dense lyes of muriate of potash. Those of muriate or sulphate of soda change the potash into a soda soap, by double decomposition. From its superior solubility, more alkaline reaction, and lower price, potash soap is preferred for many purposes, and especially for scouring woollen yarns and stuffs.

Soft soaps are usually made in this country with whale, seal, olive, and linseed oils, and a certain quantity of tallow; on the continent, with the oils of hempseed, sesame, rapeseed, linseed, poppy-seed, and colza; or with mixtures of several of these oils. When tallow is added, as in Great Britain, the object is to produce white and somewhat solid grains of stearic soap in the transparent mass, called figging, because the soap then resembles the granular texture of a fig.

The potash lyes should be made perfectly caustic, and of at least two different strengths; the weakest being of specific gravity 1·05; and the strongest, 1·20, or even 1·25. Being made from the potashes of commerce, which contain seldom more than 60 per cent., and often less, of real alkali, the lyes correspond in specific gravity to double their alkaline strength; that is to say, a solution of pure potash, of the same density, would be fully twice as strong. The following is the process followed by respectable manufacturers of soft soap (_savon vert_, being naturally or artificially green,) upon the continent.

A portion of the oil being poured into the pan, and heated to nearly the boiling point of water, a certain quantity of the weaker lye is introduced; the fire being kept up so as to bring the mixture to a boiling state. Then some more oil and lye are added alternately, till the whole quantity of oil destined for the pan is introduced. The ebullition is kept up in the gentlest manner possible, and some stronger lye is occasionally added, till the workman judges the saponification to be perfect. The boiling becomes progressively less tumultuous, the frothy mass subsides, the paste grows transparent, and it gradually thickens. The operation is considered to be finished when the paste ceases to affect the tongue with an acrid pungency, when all milkiness and opacity disappear, and when a little of the soap placed to cool upon a glass-plate, assumes the proper consistency.

A peculiar phenomenon may be remarked in the cooling, which affords a good criterion of the quality of the soap. When there is formed around the little patch, an opaque zone, a fraction of an inch broad, this is supposed to indicate complete saponification, and is called the _strength_; when it is absent, the soap is said to want its _strength_. When this zone soon vanishes after being distinctly seen, the soap is said to have _false_ strength. When it occurs in the best form, the soap is perfect, and may be secured in that state by removing the fire, and then adding some good soap of a previous round, to cool it down, and prevent further change by evaporation.

200 pounds of oil require for their saponification--72 pounds of American potash of moderate quality, in lyes at 15° B.; and the product is 460 pounds of well-boiled soap.

If hempseed oil have not been employed, the soap will have a yellow colour, instead of the green, so much in request on the continent. This tint is then given by the addition of a little indigo. This dye-stuff is reduced to fine powder, and boiled for some hours in a considerable quantity of water, till the stick with which the water is stirred, presents, on withdrawing it, a gilded pellicle over its whole surface. The indigo paste diffused through the liquid, is now ready to be incorporated with the soap in the pan, before it stiffens by cooling.

M. Thenard states the composition of soft soap at--potash 9·5, + oil 44·0, + water 46·5, = 100.

Good soft soap of London manufacture, yielded to me--potash 8·5, + oil and tallow 45, + water 46·5.

Belgian soft or green soap afforded me--potash 7, + oil 36, + water 57, = 100.

Scotch soft soap, being analyzed, gave me--potash 8, + oil and tallow 47, + water 45.

Another well-made soap--potash 9, + oil and fat 34, + water 57.

A rapeseed-oil soft soap, from Scotland, consisted of--potash 10, + oil 51·66, + water 38·33.

An olive-oil (gallipoli) soft soap, from ditto, contained--potash with a good deal of carbonic acid 10, oil 48, water 42, = 100.

A semi-hard soap, from Verviers, for fulling woollen cloth, called _savon économique_, consisted of, potash 11·5, + fat (solid) 62, + water 26·5, = 100.

The following is a common process, in Scotland, by which good soft soap is made:--

273 gallons of whale or cod oil, and 4 cwt. of tallow, are put into the soap-pan, with 250 gallons of lye from American potash, of such alkaline strength that 1 gallon contains 6600 grains of real potash. Heat being applied to the bottom pan, the mixture froths up very much as it approaches the boiling temperature, but is prevented from boiling over by being beat down on the surface, within the iron curb or crib which surmounts the cauldron. Should it soon subside into a doughy-looking paste, we may infer that the lye has been too strong. Its proper appearance is that of a thin glue. We should now introduce about 42 gallons of a stronger lye, equivalent to 8700 gr. of potash per gallon; and after a short interval, an additional 42 gallons; and thus successively till nearly 600 such gallons have been added in the whole. After suitable boiling to saponify the fats, the proper quality of soap will be obtained, amounting in quantity to 100 firkins of 64 pounds each, from the above quantity of materials.

It is generally supposed, and I believe it to be true, from my own numerous experiments upon the subject, that it is a more difficult and delicate operation to make a fine soft soap of glassy transparency, interspersed with the figged granulations of stearate of potash, than to make hard soap of any kind.

Soft soap is made in Belgium as follows:--For a boil of 18 or 20 tons, of 100 kilogrammes each, there is employed for the lyes--1500 pounds of American potashes, and 500 to 600 pounds of quicklime.

The lye is prepared cold in cisterns of hewn stone, of which there are usually five in a range. The first contains the materials nearly exhausted of their alkali; and the last the potash in its entire state. The lye run off from the first, is transferred into the second; that of the second into the third; and so on to the fifth.

In conducting the _empatage_ of the soap, they put into the pan, on the eve of the boiling-day, six _aimes_ (one ohm, = 30 gallons imperial,) of oil of colza, in summer, but a mixture of that oil with linseed oil in winter, along with two aimes of potash lye at 13° B., and leave the mixture without heat during eight hours. After applying the fire, they continue to boil gently till the materials cease to swell up with the heat; after which, lye of 16° or 17° must be introduced successively, in quantities of one quarter of an aime after another, till from 2 to 4 aimes be used. The boil is finished by pouring some lye of 20° B., so that the whole quantity may amount to 9-1/2 aimes.

It is considered that the operation will be successful, if from the time of kindling the fire till the finish of the boil, only five hours elapse. In order to prevent the soap from boiling over, a wheel is kept revolving in the pan. The operative considers the soap to be finished, when it can no longer be drawn out into threads between the finger and thumb. He determines if it contains an excess of alkali, by taking a sample out during the boil, which he puts into a tin dish; where if it gets covered with a skin, he pours fresh oil into the pan, and continues the boil till the soap be perfect. No wonder the Belgian soap is bad, amid such groping in the dark, without one ray of science!

SOFT TOILET SOAPS.

The soft fancy toilet soaps are divisible into two classes: 1. good _potash soap_, coloured and scented in various ways, forms the basis of the Naples and other ordinary soft soaps of the perfumer; 2. _pearl soap_ (_savon nacré_), which differs from the other both in physical aspect and in mode of preparation.

_Ordinary soft Toilet Soap._--Its manufacture being conducted on the principles already laid down, presents no difficulty to a man of ordinary skill and experience; the only point to be strictly attended to, is the degree of evaporation, so as to obtain soap always of uniform consistence. The fat generally preferred is good hog’s lard; of which 30 pounds are to be mixed with 45 pounds of a caustic lye marking 17° on Baumé’s scale; the temperature is to be gradually raised to ebullition, but the boil must not be kept up too long or too briskly, till after the _empatage_ or saponification is completed, and the whole of the lye intimately combined with the fatty particles; after this, the evaporation of the water may be pushed pretty quickly, by a steady boil, till copious vapours cease to rise. This criterion is observed when the paste has become too stiff to be stirred freely. The soap should have a dazzling snowy whiteness, provided the lard has been well refined, by being previously triturated in a mortar, melted by a steam heat, and then strained. The lard soap so prepared, is semi-solid, and preserves always the same appearance. If the paste is not sufficiently boiled, however, it will show the circumstance very soon; for in a few days the soap will become gluey and stringy, like a tenacious mass of birdlime. This defect may not only be easily avoided, but easily remedied, by subjecting the paste to an adequate evaporation. Such soaps are in great request for shaving, and are most convenient in use, especially for travellers. Hence their sale has become very considerable.

_Pearl soft Soap._--It is only a few years since the process for making this elegant soap became known in France. It differs little from the preceding, and owes its beautiful aspect merely to minute manipulations, about to be described. Weigh out 20 pounds of purified hog’s lard on the one hand; and 10 pounds of potash lye at 36° B. on the other. Put the lard into a porcelain capsule, gently heated upon a sand-bath, stirring it constantly with a wooden spatula; and when it is half melted, and has a milky appearance, pour into it only one-half of the lye, still stirring, and keeping up the same temperature, with as little variation as possible. While the saponification advances gradually, we shall perceive, after an hour, some fat floating on the surface, like a film of oil, and at the same time the soapy granulations falling to the bottom. We must then add the second portion of the lye; whereon the granulations immediately disappear and the paste is formed. After conducting this operation during four hours, the paste becomes so stiff and compact, that it cannot be stirred; and must then be lightly beaten. At this time the capsule must be transferred from the sand-bath into a basin of warm water, and allowed to cool very slowly.

The soap, though completely made, has yet no pearly appearance. This physical property is developed only by pounding it strongly in a marble mortar; whereby all its particles, which seemed previously separated, combine to form a homogeneous paste. The perfume given to it, is always essence of bitter almonds; on which account the soap is called _almond cream_, _crème d’amandes_.

HARD SOAPS FOR THE TOILET.

The soaps prepared for the perfumer, are distinguished into different species, according to the fat which forms their basis. Thus there is soap of tallow, of hog’s lard, of oil of olives, of almonds, and palm oil.

It is from the combination of these different sorts, mingled in various proportions, and perfumed agreeably to the taste of the consumer, that we owe the vast number of toilet soaps sold under so many fantastic names. One sort is rarely scented by itself, as a mixture of several is generally preferred; in which respect every perfumer has his peculiar secret. Some toilet soaps, however, require the employment of one kind more than of another.

Formerly the Windsor soap was made in France, wholly with mutton suet; and it was accordingly of inferior value. Now, by mixing some olive oil or lard with the suet, a very good Windsor soap is produced. I have already stated, that the fat of the London Windsor is, nine parts of good ox tallow, and one of olive oil. A soap made entirely with oil and soda, does not afford so good a lather as when it contains a considerable proportion of tallow.

The soaps made with palm oil are much used; when well made, they are of excellent quality, and ought to enter largely into all the coloured sorts. They naturally possess the odour of violets.

The soaps made with oil of almonds are very beautiful, and preserve the agreeable smell of their perfume; but being expensive, are introduced sparingly into the mixtures by most manufacturers.

Some perfumers are in the habit of making what may be called extempore soaps, employing lyes at 36° Baumé in their formation. This method, however, ought never to be adopted by any person who prefers quality to beauty of appearance. Such soap is, indeed, admirably white, glistening, contains no more water than is necessary to its constitution, and may therefore be sold the day after it is made. But it has counterbalancing disadvantages. It becomes soon very hard, is difficultly soluble in water, and, if not made with tallow, does not lather well. Hog’s lard is very commonly used, for making that soap. Twenty kilogrammes of the fat are taken, to ten kilogrammes of soda lye, at 36° B. (specific gravity 1·324); as soon as the former is nearly fluid, 5 kilogrammes of the lye are introduced, and the mixture is continually agitated during an hour with a wooden spatula. The temperature should never be raised above 150° Fahr. at the commencement of the operation; at the end of one hour, 5 other kilogrammes of lye are to be added, with careful regulation of the heat. The paste thus formed by the union of the fat and alkali, ought to be perfectly homogeneous, and should increase in consistence every hour, till it becomes firm enough to be poured into the frame; during which transfer, the essential oils destined to scent it, should be introduced. Next day the soap is hard enough; nor does it differ in appearance from ordinary soap, only it requires prompt manipulation to be cut into bars and cakes; for when neglected a day or two, it may become too brittle for that purpose, and too hard to take the impression of the stamps in relief. Such an article gets the name of _little-pan soap_, on account of the small quantity in which it is usually manufactured. Hard soap, made in the common way, is, on the contrary, called _large-pan soap_. This extemporaneous compound is now seldom or never made by respectable manufacturers. In making Windsor soap, the admixture of olive oil is advantageous; because, being richer in oleine than suet, it saponifies less readily than it, and thus favours the formation of a more perfect neutral combination. When the soap cuts, or parts from the lye, when the paste becomes clotty, or, in the language of the operative, when the grain makes its appearance, the fire should be immediately withdrawn, that the impurities may be allowed to subside. This part of the operation lasts 12 hours at least; after which, the soap, still hot, becomes altogether fluid and perfectly neutral.

For every 1000 pounds of the paste, there must be introduced 9 pounds of essences, mingled in the following proportions:--6 pounds of essence of carui; 1-1/2 ditto lavender (finest); 1-1/2 ditto rosemary.

The mixture must be well stirred, in order to get completely saturated with the perfumes; and this may be readily done without at all touching or stirring up the subjacent lyes; in the course of two hours, the soap may be transferred into the ordinary frames. In twenty-four hours, the mass is usually solidified enough for cutting into bars and cakes, ready to be stamped for sale.

The above method of scenting Windsor soap is practised only in the largest establishments; in the smaller, the soap is pailed out of the soap-pans, into a pan provided with a steam case or jacket, and there mixed with the essential oils, by means of appropriate heat and agitation.

The most fashionable toilet soaps are, the rose, the _bouquet_, the cinnamon, the orange-flower, the musk, and the bitter almond or peach blossom.

_Soap à la rose._--This is made of the following ingredients: 30 pounds of olive-oil soap; 20 of good tallow soap.

Toilet soaps must be reduced to thin shavings, by means of a plane, with its under face turned up, so that the bars may be slid along it. These shavings must be put into an untinned copper pan, which is surrounded by a water-bath, or steam. If the soap be old and hard, 5 pounds of water must be added to them; but it is preferable to take fresh-made soaps, which may melt without addition, as soap some time kept does not readily form a homogeneous paste. The fusion is commonly completed in an hour, or thereby, the heat being applied at 212° F., to accelerate the progress, and prevent the dissolution of the constituent water of the soap. For this purpose the interior pan may be covered. Whenever the mass is sufficiently liquefied, 1-1/2 ounces of finely ground vermillion are to be introduced, and thoroughly mixed, after which the heat may be taken off the pan; when the following perfumes may be added with due trituration:--3 ounces of essence of rose; 1 ditto cloves; 1 ditto cinnamon; 2-1/2 ditto bergamot; = 7-1/2.

The scented soap being put into the frames, speedily consolidates. Some recommend to pass the finished fused soap through a tammy cloth, in order to free it from all clots and impurities; a very proper precaution in the act of transferring it to the frame. If the preceding instructions be observed, we obtain a soap perfect in every point of view; possessing a delicious fragrance, equally rich and agreeable, a beautiful roseate hue, and the softest detergent qualities, which keeping cannot impair. Such a soap has, in fact, been known to retain every property in perfection during four or five years. When the essential oils are particularly volatile, they should not be added to the soap till its temperature has fallen to about 140° Fahr.; but in this case a more careful trituration is required. The economy is, however, ill bestowed; for the cakes made of such cooler soap, are never so homogeneous and glossy.

_Soap au bouquet._--30 pounds of good tallow soap; 4 ounces of essence of bergamot; oil of cloves, sassafras, and thyme, 1 ounce each; neroli, 1/2 ounce. The colour is given with 7 ounces of brown ochre.

_Cinnamon Soap._--30 pounds of good tallow soap; 20 ditto of palm-oil soap. Perfumes:--7 ounces of essence of cinnamon; 1-1/4 ditto sassafras; 1-1/4 ditto bergamot. Colour:--1 pound of yellow ochre.

_Orange-flower Soap._--30 pounds of good tallow soap; 20 ditto palm-oil soap. Perfumes:--7-1/2 ounces essence of Portugal; 7-1/2 ditto amber. Colour:--9-1/2 ounces, consisting of 8-1/4 of a yellow-green pigment, and 1-1/4 of red lead.

_Musk Soap._--30 pounds of good tallow soap; 20 ditto palm-oil soap. Perfumes:--Powder of cloves, of pale roses, gilliflower, each 4-1/2 ounces; essence of bergamot, and essence of musk, each 3-1/2 ounces. Colour:--4 ounces of brown ochre, or Spanish brown.

_Bitter Almond Soap._--Is made by compounding, with 50 pounds of the best white soap, 10 ounces of the essence of bitter almonds.

LIGHT SOAPS.

The apparatus employed for making these soaps, is a copper pan, heated by a water-bath; in the bottom of the pan there is a step, to receive the lower end of a vertical shaft, to which arms or paddles are attached, for producing constant agitation, by causing them to revolve among the liquefied mass. Into a pan so mounted, 50 pounds of a good oil soap of any kind are put (for a tallow soap does not become frothy enough), and melted by proper heat, with the addition of 3 or 4 pounds of water. By the rapid rotation of the machine, an abundant thick lather is produced, beginning first at the bottom, and creeping gradually upwards to the top of the pan, when the operation should be stopped; the soap having by this time doubled its volume. It must now be pailed off into the frame, allowed to cool, and then cut into cakes. Such soap is exceedingly pleasant at the wash-stand, feeling very soft upon the skin, affording a copious thick lather, and dissolving with the greatest ease.

TRANSPARENT SOAPS.

These soaps were for a long time manufactured only in England, where the process was kept a profound secret. They are now made every where.

Equal parts of tallow soap, made perfectly dry, and spirit of wine, are to be put into a copper still, which is plunged in a water-bath, and furnished with its capital and refrigeratory. The heat applied to effect the solution should be as slight as possible, to avoid evaporating too much of the alcohol. The solution being effected, must be suffered to settle; and after a few hours’ repose, the clear supernatant liquid is drawn off into tin frames, of the form desired for the cakes of soap. These bars do not acquire their proper degree of transparency till after a few weeks’ exposure to dry air. They are now planed, and subjected to the proper mechanical treatment for making cakes of any form. The soap is coloured with strong alcoholic solution of archil for the rose tint, and of turmeric for the deep yellow. Transparent soaps, however pleasing to the eye, are always of indifferent quality; they are never so detergent as ordinary soaps, and they eventually acquire a disagreeable smell.

+---------------------------+-----------+-----------+-----------+ | Soap charged with duty in | 1834. | 1835. | 1836. | +---------------------------+-----------+-----------+-----------+ | | _lbs._ | _lbs._ | _lbs._ | |Hard |144,344,043|143,806,207|146,539,210| |Soft | 10,401,281| 12,103,109| 13,358,894| | | | | | |Amount of duty at 1-1/2_d._| | | | |per lb. on hard soap | _£_902,150| _£_930,039| _£_915,861| | do. at 1_d._ | | | | | soft soap | 43,339| 50,429| 55,662| +---------------------------+-----------+-----------+-----------+

SOAPSTONE; see STEATITE.

SODA, _Caustic soda_ (_Hydrate de soude_, Fr.; _Aetznatron_, Germ.); is an alkaline substance, used in chemical researches, in bleaching, and in the manufacture of soap. It is prepared by boiling a solution of crystallized carbonate of soda in 4 or 5 parts of water, with half its weight of recently slaked and sifted lime. At the end of half an hour, the vessel of iron, porcelain, or preferably silver, may be removed from the fire, and covered carefully, till the calcareous matter has settled into a solid magma at the bottom. The clear supernatant lye may be then decanted into bottles for use in the liquid state, or evaporated, out of contact of air, till it assumes an oily appearance, then poured upon an iron or marble slab, broken into pieces, and put up in phials secured with greased stoppers or corks.

Caustic soda is a white brittle mass, of a fibrous texture, a specific gravity of 1·536, melting at a heat under redness, having a most corrosive taste and action upon animal matters, dissolving readily in both water and alcohol, attracting carbonic acid when exposed to the atmosphere, but hardly any water, and falling thereby into an efflorescent carbonate; it forms soaps with tallow, oils, wax, rosin; dissolves wool, hair, silk, horn, alumina, silica, sulphur, and some metallic sulphurets. It consists of 77·66 soda, and 22·34 water. A solution of caustic soda affords no precipitate with solution of chloride of platinum, or tartaric acid, as a solution of caustic potash never fails to do.

The following TABLE of the quantity of CAUSTIC SODA contained in LYES of different densities, has been given by Richter:--

+-----+---------+ |Spec.| Soda | |grav.|per cent.| +-----+---------+ | 1·00| 0·00 | | 1·02| 2·07 | | 1·04| 4·02 | | 1·06| 5·89 | | 1·08| 7·69 | | 1·10| 9·43 | | 1·12| 11·10 | | 1·14| 12·81 | | 1·16| 14·73 | | 1·18| 16·73 | | 1·20| 18·71 | | 1·22| 20·66 | | 1·24| 22·58 | | 1·26| 24·47 | | 1·28| 26·33 | | 1·30| 28·16 | | 1·32| 29·96 | | 1·34| 31·67 | | 1·35| 32·40 | | 1·36| 33·08 | | 1·38| 34·41 | +-----+---------+

Soda free from water, can be obtained only by the combustion of _sodium_, which see.

SODA, CARBONATE OF (_Kohlensaures natron_, Germ.): is the soda of commerce in various states, either crystallized, in lumps, or in a crude powder called soda-ash. It exists in small quantities in certain mineral waters; as, for example, in those of Seltzer, Seydschutz, Carlsbad, and the volcanic springs of Iceland, especially the Geyser; it frequently occurs as an efflorescence in slender needles upon damp walls, being produced by the action of the lime upon the sea salt present in the mortar. The mineral soda is the sesquicarbonate, to be afterwards described.

Of manufactured soda, the variety most antiently known is barilla, the incinerated ash of the _Salsola soda_. This plant is cultivated with great care by the Spaniards, especially in the vicinity of Alicant. The seed is sown in light low soils, which are embanked towards the sea shore, and furnished with sluices, for admitting an occasional overflow of salt water. When the plants are ripe, the crop is cut down and dried; the seeds are rubbed out and preserved; the rest of the plant is burned in rude furnaces, at a temperature just sufficient to cause the ashes to enter into a state of semi-fusion, so as to concrete on cooling into cellular masses moderately compact. The most valuable variety of this article is called _sweet barilla_. It has a grayish-blue colour and gets covered with a saline efflorescence when exposed for some time to the air. It is hard and difficult to break; when applied to the tongue, it excites a pungent alkaline taste.

I have analyzed many varieties of barilla. Their average quantity of free or alkalimetrical soda, is about 17 per cent.; though several contain only 14 parts in the hundred, and a few upwards of 20. This soda is chiefly a carbonate, with a little sulphuret and sulphite; and is mixed with sulphate and muriate of soda, carbonate of lime, vegetable carbon, &c.

Another mode of manufacturing crude soda, is by burning sea-weed into kelp. Formerly very large revenues were derived by the proprietors of the shores of the Scottish islands and Highlands, from the incineration of sea-weed by their tenants, who usually paid their rents in kelp; but since the tax has been taken off salt, and the manufacture of a crude soda from it has been generally established, the price of kelp has fallen extremely low.

The crystals of soda-carbonate, as well as the soda-ash of British commerce, are now made altogether by the decomposition of sea salt.

SODA MANUFACTURE.

The manufacture divides itself into three branches:--1. The conversion of sea salt, or chloride of sodium, into sulphate of soda. 2. The decomposition of this sulphate into crude soda, called _black balls_ by the workmen. 3. The purification of these balls, either into a dry white soda-ash or into crystals.

1. _The preparation of the sulphate of soda._--_Figs._ 1033, 1034, 1035. represent the furnace for converting the muriate of soda into the sulphate. The furnace must be built interiorly of the most refractory fire-bricks, such as are used for glasshouses, but of the ordinary brick size; except the bridges C, G, N, which should be formed of one mass, such as what is called a Welsh lump. A is the ash-pit; B, the grate; C, the first bridge, between the fire and the first calcining hearth, D, D; F, F, is its roof; G, the second bridge, between the calcining hearth and the decomposing hearth I, I, I; the roof of which is K, K. This hearth I, I, is lined with a lead square pan, 5 or 6 inches deep, sloped at the back opening, in _fig._ 1035., marked M´; which deficient part of the upright side is filled up with two bricks placed one over the other, as shown at _m_, _m_, _fig._ 1034., and luted with clay, to confine the semi-liquid mass in the pan, I, I. Some manufacturers make this pan 8 inches deep, and line its bottom and sides with bricks or siliceous sandstone, to protect the lead from the corrosive action of the acid. There are others who consider this precaution troublesome, as the points of the pan which become leaky are thereby concealed. In the roof of the decomposing hearth, one or two syphon funnels R, of lead, are inserted when the charge of acid (sulphuric) is to be poured down upon the salt in I, I, to save the risk of any annoyance from the fumes of the muriatic acid. O, O, is a chimney filled with round flint nodules, which are kept continually moist by the trickling of a streamlet of water upon the topmost layer. The muriatic gas meeting this descending film of water upon so extensive a surface, becomes absorbed, and runs out below in a liquid form. When the acid is required in a somewhat concentrated state, this chimney should be made both high and capacious. Such a plan, moreover, is very valuable for abating the nuisance caused by the disengagement of the muriatic acid gas; which is otherwise apt to sterilize the surrounding vegetation.

A fire being kindled in the grate B, _figs._ 1033. and 1034., 3 cwt. of salt in powder are to be thrown by a shovel into the pan I, through the door M, _fig._ 1035., or _m_, _m_, _fig._ 1034. Two hundred weight and a half of oil of vitriol, of specific gravity 1·844 having been diluted with from 25 to 30 per cent. of water, and well mixed, or 3 cwts. at 56° Baumé, are to be slowly poured in by the funnel, and diffused among the muriate of soda, by an occasional stir with an iron rake cased with sheet lead. Fumes of muriatic acid will now plentifully escape, and, passing up the condensing-shaft O, will flow down in the form of liquid spirit of salt, and escape by the stoneware stopcock P, into the pipe of a sunk cistern. The fire having been steadily kept up at a moderate degree, the chemical reaction will be tolerably complete in the course of two hours; but as this is relative to the nature of the fuel, and the draught of the furnace, no very precise rule in point of time can be laid down; but it is sufficient for this stage of the process, when the fumes cease to be very dense and copious, as may be ascertained by opening the door M, and looking in, or by the appearance at the top of the shaft O. Over the door M´, in the opposite side of the decomposing hearth, _fig._ 1035., there must be an arch or hood terminating in a small chimney, 15 or 20 feet high, for the ascent of the muriatic vapours, when the charge is drawn or run out of the hearth, and allowed to fall into a square shallow iron tray, placed on the ground at the back of the furnace. For this discharge, the two bricks which serve as stoppers to that orifice, must be unluted and removed.

As soon as that charge is taken out, (the fire being meanwhile checked by opening the door T, _fig._ 1034., and shutting partially the ash-pit opening at A,) a fresh charge must be introduced as above described. The nearly decomposed saline matter during the second charging of the hearth I, will have grown cool and concrete. It must be shovelled into the calcining hearth D, D, _fig._ 1033., by the back door Q, _fig._ 1035., where it will receive a higher degree of heat; and, by the expulsion of the remaining part of the muriatic acid, it will become a perfect sulphate of soda. It should be finally brought into a state of semi-fusion. When a sample of it, taken out on the end of the rake or trowel-shaped scraper, emits no fumes, the conversion is accomplished.

From 3 cwts. of common salt, or muriate of soda, rather more than 3-1/2 cwts. of perfect sulphate should be obtained, quite free from metallic impurity.

The next step is the conversion of the sulphate into a crude soda.

One of the most improved soda furnaces is that, employed in a few factories, represented in _figs._ 1036, 1037, and 1038. In the section _fig._ 1037., there are two hearths in one furnace, the one elevated above the level of the other by the thickness of a brick, or about 3 inches. A is the preparatory shelf, where the mixture to be decomposed is first laid in order to be thoroughly heated, so that when transferred to the lower or decomposing hearth B, it may not essentially chill it, and throw back the operation. C is the fire-bridge, and D is the grate. In the horizontal section, or ground plan, _fig._ 1038., we see an opening in the front corresponding to each hearth. This is a door, as shown in the side view or elevation of the furnace, _fig._ 1036.; and each door is shut by an iron square frame filled with a fire-tile or bricks, and suspended by a chain over a pulley fixed in any convenient place. See PITCOAL, COKING OF, p. 1041. The workman, on pushing up the door lightly, makes it rise, because there is a counterweight at the other end of each chain, which balances the weight of the frame and bricks. In the ground plan, only one smoke-flue is shown; and this construction is preferred by many manufacturers; but others choose to have two flues, one from each shoulder, as at _a_, _b_; which two flues afterwards unite in one vertical chimney, from 25 to 40 feet high; because the draught of a soda-furnace must be very sharp. Having sufficiently explained the construction of this improved furnace, I shall now proceed to describe the mode of making soda with it.

The materials with which the sulphate is decomposed into a rough carbonate of soda, are chalk or ground limestone, and ground coal or charcoal. The proportions in which these three substances are mixed, influence in a remarkable degree the success of the decomposing process. I have known a false proportion introduced, and persevered in, at a factory, with the most prejudicial effect to the product; the soda-ash produced, being in a small quantity relatively to the sulphate employed, and being much charged with sulphur. After very numerous trials which I have made on the great scale, and many inquiries at the most successful soda-works, both in this country and abroad, I am warranted to offer the following proportions as the most profitable:--

Sulphate of soda, 100 parts: carbonate of lime (chalk or limestone), from 110 to 120 parts; if pure, 110; if a little impure or damp, 120: pit coal, 50 parts.

These materials must be separately ground by an edge-stone mill, and sifted into a tolerably fine powder. They must be then very carefully mixed. Attention to these particulars is of no little importance to the success of the soda process.

One hundred parts or pounds of sulphate of soda are equivalent to 75 parts of carbonate, and when skilfully decomposed, will generally yield fully 70 pounds. A charge for the decomposing furnace with the preparatory shelf should not exceed 200 lbs., or perhaps 180; therefore if 75 pounds of ground sulphate of soda, with 80 pounds of chalk or limestone (ground), and 37 pounds of ground coal; be well mixed, they will constitute one charge. This charge must be shovelled in upon the hearth A, or shelf of preparation, (_fig._ 1037.); and whenever it has become hot (the furnace having been previously brought to bright ignition), it is to be transferred to the decomposing hearth or laboratory B, by an iron tool, shaped exactly like an oar, called the spreader. This tool has the flattened part from 2 to 3 feet long, and the round part, for laying hold of and working by, from 6 to 7 feet long. Two other tools are used; one, a rake, bent down like a garden hoe at the end; and another, a small shovel, consisting of a long iron rod terminated with a piece of iron plate, about 6 inches long, 4 broad, sharpened and tipped with steel, for cleaning the bottom of the hearth from adhering cakes or crusts. Whenever the charge is shoved by the sliding motion of the oar down upon the working hearth, a fresh charge should be thrown into the preparation shelf, and evenly spread over its surface.

The hot and partially carbonized charge being also evenly spread upon the hearth B, is to be left untouched for about ten minutes, during which time it becomes ignited, and begins to fuse upon the surface. A view may be taken of it through a peep-hole in the door, which should be shut immediately, in order to prevent the reduction of the temperature. When the mass is seen to be in a state of incipient fusion, the workman takes the oar and turns it over breadth by breadth in regular layers, till he has reversed the position of the whole mass, placing on the surface the particles which were formerly in contact with the hearth. Having done this, he immediately shuts the door, and lets the whole get another decomposing heat. After five or six minutes, jets of flame begin to issue from various parts of the pasty-consistenced mass. Now is the time to incorporate the materials together, turning and spreading by the oar, gathering them together by the rake, and then distributing them on the reverse part of the hearth; that is, the oar should transfer to the part next the fire-bridge the portion of the mass lying next the shelf, and _vice versâ_. The dexterous management of this transposition characterizes a good soda-furnacer. A little practice and instruction will render this operation easy to a robust clever workman. After this transposition, incorporation, and spreading, the door may be shut again for a few minutes, to raise the heat for the finishing off. Lastly, the rake must be dexterously employed to mix, shift, spread, and incorporate. The jets, called _candles_, are very numerous, and bright at first; and whenever they begin to fade, the mass must be raked out into cast-iron moulds, placed under the door of the laboratory to receive the ignited paste.

One batch being thus worked off, the other, which has lain undisturbed on the shelf, is to be shoved down from A to B, and spread equally upon it, in order to be treated as above described. A third batch is then to be placed on the shelf.

The article thus obtained should contain at least 22 per cent. of real soda, equivalent to 37 per cent. of dry carbonate, or to 100 of crystals. A skilful workman can turn out a batch in from three quarters of an hour to an hour, producing a perfect carbonate, which yields on solution an almost colourless liquid, nearly destitute of sulphur, and containing hardly any decomposed sulphate.

In some soda-works, where the decomposing furnace is very large, and is charged with a ton of materials at a time, it takes two men to work it, and from five to six hours to complete a batch. Having superintended the operation of the above-described small furnace, and examined its products, I feel warranted to recommend its adoption.

The following materials and products show the average state of this soda process:--

_Materials_--100 parts of sulphate of soda, ground, equivalent to 7·5 of carbonate; 110 of chalk or ground limestone; 55 of ground coal: in the whole, 265.

_Products_--168 parts of crude soda, at 33 per cent. = 55·5 of dry carbonate. { 130 -- crystals of carbonate of soda = 48 of dry Or, { carbonate; and { 100 -- insoluble matter.

But these products necessarily vary with the skill of the workman.

In another manufactory the following proportions are used:--Six stones, of 14 lbs. each, of dry ground sulphate of soda, are mixed with 3 of chalk and 3 of coal. This mixture, weighing 1-1/2 cwt., forms a batch, which is spread upon the preparation shelf of the furnace (_figs._ 1037. and 1038.), as above described, and gradually heated to incipient ignition. It is then swept forwards to the lower area B, by the iron oar, and spread evenly by the rake. Whenever it begins to soften under the rising heat of the laboratory (the side doors being meanwhile shut), the mass must be laboriously turned over and incorporated; the small shovel, or paddle, being employed to transfer, by the interchange of small portions at a time, in rapid but orderly succession, the whole materials from the colder to the hotter, and from the hotter to the colder parts of the hearth. The process of working one batch takes about an hour, during the first half of which period it remains upon the preparation shelf. The average weight of the finished ball is 1 cwt., and its contents in alkalimetrical soda are 33 pounds.

Where the acidulous sulphate of iron from pyrites may be had at a cheap rate, it has been long ago employed, as at Hurlett in Scotland, instead of sulphuric acid, for decomposing the chloride of sodium. Mr. Turner’s process of preparing soda, by decomposing sea salt with litharge and quicklime, has been long abandoned, the resulting patent yellow, or sub-chloride of lead, having a very limited sale.

2. _The extraction of pure soda from the crude article._--The black balls must be broken into fragments, and thrown into large square iron cisterns, furnished with false bottoms of wooden spars; when the cisterns are nearly full of these lumps, water is pumped in upon them, till they are all covered. After a few days, the lixiviation is effected, and the lye is drawn off either by a syphon or by a plug-hole near the bottom of the cistern, and run into evaporating vessels. These may be of two kinds. The surface-evaporating furnace, shown in _fig._ 1039., is a very admirable invention for economizing vessels, lime, and fuel. The grate A, and fireplace, are separated from the evaporating laboratory D, by a double fire-bridge B, C, having an interstitial space in the middle, to arrest the communication of a melting or igniting heat towards the lead-lined cistern D. This cistern may be 8, 10, or 20 feet long, according to the magnitude of the soda-work, and 4 feet or more wide. Its depth should be about 4 feet. It consists of sheet lead, of about 6 pounds weight to the square foot, and it is lined with one layer of bricks, set in roman or hydraulic cement, both along the bottom and up the sides and ends. The lead comes up to the top of C, and the liquor, or lye, may be filled in to nearly that height. Things being thus arranged, a fire is kindled upon the grate A; the flame and hot air sweep along the surface of the liquor, raise its temperature there rapidly to the boiling point, and carry off the watery parts in vapour up the chimney E, which should be 15 or 20 feet high, to command a good draught. But, indeed, it will be most economical to build one high capacious chimney stalk, as is now done at Glasgow, Manchester, and Newcastle, and to lead the flues of the several furnaces above described into it. In this evaporating furnace the heavier and stronger lye goes to the bottom, as well as the impurities, where they remain undisturbed. Whenever the liquor has attained to the density of 1·3, or thereby, it is pumped up into evaporating cast-iron pans, of a flattened somewhat hemispherical shape, and evaporated to dryness while being diligently stirred with an iron rake and iron scraper.

This alkali gets partially carbonated by the above surface-evaporating furnace, and is an excellent article.

When pure carbonate is wanted, that dry mass must be mixed with its own bulk of ground coal, sawdust, or charcoal, and thrown into a reverberatory furnace, like _fig._ 1038., but with the sole all upon one level. Here it must be exposed to a heat not exceeding 650° or 700° F.; that is, a little above the melting heat of lead; the only object being to volatilize the sulphur present in the mass, and carbonate the alkali. Now, it has been found, that if the heat be raised to distinct redness, the sulphur will not go off, but will continue in intimate union with the soda. This process is called calking, and the furnace is called a calker furnace. It may be six or eight feet long, and four or five feet broad in the hearth, and requires only one door in its side, with a hanging iron frame filled with a fire-tile or bricks, as above described.

This carbonating process may be performed upon several cwts. of the impure soda, mixed with sawdust, at a time. It takes three or four hours to finish the desulphuration; and it must be carefully turned over by the oar and the rake, in order to burn the coal into carbonic acid, and to present the carbonic acid to the particles of caustic soda diffused through the mass, so that it may combine with them.

When the blue flames cease, and the saline matters become white, in the midst of the coaly matter, the batch may be considered as completed. It is raked out, and when cooled, lixiviated in great iron cisterns with false bottoms, covered with mats. The watery solution being drawn off clear by a plug-hole, is evaporated either to dryness, in hemispherical cast-iron pans, as above described, or only to such a strength that it shows a pellicle upon its surface, when it may be run off into crystallizing cisterns of cast iron, or lead-lined wooden cisterns. The above dry carbonate is the best article for the glass manufacture.

_Crystallized carbonate of soda_, contains 62-3/4 per cent. of water. The crystals are colourless transparent rhomboids, which readily effloresce in the air, and melt in their own water of crystallization. On decanting the liquid from the fused mass, it is found that one part of the salt has given up its water of crystallization to another. By evaporation of that fluid, crystals containing one-fifth less water than the common carbonate are obtained. These do not effloresce in the air.

_Mineral soda_, the sesquicarbonate, (_Anderthalb kohlensaures natron_, Germ.); is found in the province of Sukena, in Africa, between Tripoli and Fezzan. It forms a stratum no more than an inch thick, just below the surface of the soil. Its texture is striated crystalline, like fibrous gypsum. Several hundred tons of it are collected annually, which are chiefly consumed in Africa. This species of soda does not effloresce like the Egyptian, or the manufactured soda crystals, owing to its peculiar state of composition and density. It was analyzed by Klaproth, under its native name of _trona_, and was found to consist, in 100 parts, of--soda, 37; carbonic acid, 38; sulphate of soda, 2·5; water, 22·5, in 100.

This soda is, therefore, composed of--3 atoms of carbonic acid, associated with 2 atoms of soda, and 4 of water; while our commercial soda crystals are composed of--1 atom of carbonic acid, 1 atom of soda, and 10 atoms of water.

There are six natron lakes in Egypt. They are situated in a barren valley, called Bahr-bela-ma, about thirty miles to the west of the Delta.

There are natron lakes also in Hungary, which afford in summer a white saline efflorescent crust of carbonate of soda, mixed with a little sulphate.

There are several soda lakes in Mexico, especially to the north of Zacatecas, as also in many other provinces. In Columbia, 48 English miles from Merida, mineral soda is extracted from the earth in great abundance, under the name of _urao_.

_Bicarbonate of soda_ (_Doppelt kohlensaures natron_, Germ.); is prepared, like bicarbonate of potassa, by transmitting carbonic acid gas through a cold saturated solution of pure carbonate of soda, till crystalline crusts be formed. The bicarbonate may also be obtained in four-sided tables grouped together. It has an alkaline taste and reaction upon litmus paper, dissolves in 13 parts of cold water, and is converted by boiling water into the sesquicarbonate, with the disengagement of one fourth of its carbonic acid. It consists of--37 of soda, 52·35 carbonic acid, and 10·65 water.

SODA-WATER, is the name given to water containing a minute quantity of soda, and highly charged with carbonic acid gas, whereby it acquires a sparkling appearance, an agreeable pungent taste, an exhilarating quality, and certain medicinal powers. It constitutes a considerable object of manufacture in this kingdom. The following figure represents, I understand, the best system of apparatus for preparing it. A very dilute solution of soda is put into the globular vessel H, and the carbonic acid gas is forced into it from the gasometer E, by means of the powerful pump-work, as will be understood from the subjoined explanation.

The same apparatus may serve for making any species of aerated water, in imitation of any natural spring. All that is necessary for this purpose, is to put into the cistern Q, the neutro-saline matter, earths, metallic oxides, pure water, &c., each in due proportion, according to the most accredited analysis of the mineral water to be imitated, to agitate that mixture, to suck it into the condenser H, through the pipe R, and then to impregnate it to the due degree, by pumping in the appropriate gas, previously contained in the gasometer F.

Thus, to make Seltzer water, for each 12 pounds troy, = 69,120 grains, or 1 gallon imperial very nearly, take 55 grains of dry carbonate of soda, 17 of carbonate of lime, 18 of carbonate of magnesia, 3-1/2 of subphosphate of alumina, 3 of chloride of potassium, 155 of chloride of sodium, and 3 of finely precipitated silica. Put these materials into the cistern Q, and charge the gasometer F with 353 cubic inches of carbonic acid gas. Then work the machine by the handle of the wheel X, as explained below, and regulate the introduction of the liquid and the gas in aliquot portions; for example, if the condenser H admits half a gallon of water at a time, that quantity of liquid should be charged with 176 cubic inches of the gas, being one half of the whole quantity. The sulphuretted mineral waters may be imitated in like manner, by taking the proportions of their constituents, as given in Table II. of WATERS, MINERAL.

IMPROVED SODA-WATER APPARATUS, AS MADE BY MR. HAYWARD TYLER, OF MILTON STREET.

_Fig._ 1040. front view of the soda-water machine. _Fig._ 1041. end view of the same.

A, lead generator, for making the gas. B, lead pot, for holding sulphuric acid. C, handle for moving the agitator of the receiver, which stirs up the ingredients in the lead generator. _a_, cap and screw, for charging the lead pot with sulphuric acid. _b_, swivel-joint, which is movable, for occasionally throwing in portions of sulphuric acid for generating gas. _c_, stuffing-box for agitator. _d_, large cap and screw, for charging the lead generator with whiting and water. _e_, cap and screw, for emptying contents of ditto. D, lead pipe, to convey the gas from the lead generator to gasometer. E, wood tub, filled with water, for gasometer to work in. F, copper gasometer. G, strong iron frame, for gasometer and tub to stand on, firmly fixed together by three wrought-iron rods, _f_, _f_. _g_, _g_, two pulleys, for carrying rope and counterbalance weight _h_, for balancing copper gasometer. _i_, cock for discharging atmospheric air contained in the gasometer before making the gas. _k_, cock for occasionally emptying the water out of the tub. _l_, union joint, to which is fixed a copper pipe, passing through the water in the tub, to deliver the gas as generated into the copper gasometer. _m_, another union joint, with a similar copper pipe, passing through the water in the tub, and projecting two or three inches above the surface of the water, to convey the gas from the copper gasometer to the soda-water machine. H, H, condenser for aerating the soda-water. I, safety valve. K, K, bottling valve. L, bottling nipple. M, M, soda-water pump. N, valve-piece. O, O, piston of the pump. P, pipe for conducting gas from the gasometer to pump. Q, copper pan for holding the solution of soda. R, copper pipe for conducting the solution of soda to the force pump. S, S, two cocks for regulating the admission of the solution and gas to the pump. T, copper pipe through which the soda-water is forced to the condenser. U, pinion wheel, to give motion to the agitator revolving inside the condenser. V, V, wheel for driving ditto. W, W, cast-iron frame for carrying machinery. X, X, cast-iron fly-wheel. Z, wrought-iron crank. Y, Z, Z, wood stools and curb, upon which the whole of the machinery is fixed.

SODIUM, the metallic basis of soda, is obtained by processes similar to those by which potassium is procured. By fusing hydrate of soda with a little hydrate of potassa, a mixture is obtained, which yields more readily than soda by itself to the decomposing action of iron-turnings at a high heat, in a bent gun-barrel. The portion of potassium produced, may be got rid of, by digesting the alloy for a few days in some naphtha or oil of turpentine contained in an open vessel. The sodium remains at the bottom of the liquid. Pure sodium may, however, be prepared at once, by subjecting incinerated tartrate of soda to heat in the apparatus of Brunner, described under POTASSIUM. It is white, like silver; softer and more malleable than any other metal, and may be readily reduced into very thin leaves. It preserves its malleability till it approaches the melting point. Its specific gravity is 0·970. It softens at the temperature of 122° F., and at 200° it is perfectly fluid; but it will not rise in vapour until heated to nearly the melting point of glass. In the air it oxidizes slowly, and gets covered with a crust of soda; but it does not take fire till it is made nearly red-hot; and then it emits brilliant scintillations. When thrown upon water, it is rapidly oxidized, but without kindling, like potassium. If a drop of water be thrown upon it, it becomes so hot by the chemical action as to take fire. There are three oxides of sodium; 1. the suboxide; 2. the oxide, or the basis of common soda; and, 3. the suroxide; the last being formed when sodium is heated to redness upon a plate of silver.

SOLDERING (_Souder_, Fr.; _Löthen_, Germ.); is the process of uniting the surfaces of metals, by the intervention of a more fusible metal, which being melted upon each surface, serves, partly by chemical attraction, and partly by cohesive force, to bind them together. The metals thus united may be either the same or dissimilar; but the uniting metal must always have an affinity for both. Solders must be, therefore, selected in reference to their appropriate metals. Thus tin-plates are soldered with an alloy consisting of from 1 to 2 parts of tin, with 1 of lead; pewter is soldered with a more fusible alloy, containing a certain proportion of bismuth added to the lead and tin; iron, copper, and brass are soldered with spelter, an alloy of zinc and copper, in nearly equal parts; silver, sometimes with pure tin, but generally with silver-solder, an alloy consisting of 5 parts of silver, 6 of brass, and 2 of zinc; zinc and lead, with an alloy of from 1 to 2 parts of lead with 1 of tin; platinum, with fine gold; gold, with an alloy of silver and gold, or of copper and gold; &c.

In all soldering processes, the following conditions must be observed: 1. the surfaces to be united must be entirely free from oxide, bright, smooth, and level; 2. the contact of air must be excluded during the soldering, because it is apt to oxidize one or other of the surfaces, and thus to prevent the formation of an alloy at the points of union. This exclusion of air is effected in various ways. The locksmith encases in loam the objects of iron, or brass, that he wishes to subject to a soldering heat; the silversmith and brazier mix their respective solders with moistened borax powder; the coppersmith and tinman apply sal ammoniac, rosin, or both, to the cleaned metallic surfaces, before using the soldering-iron to fuse them together with the tin alloy. The strong solder of the coppersmith consists of 8 parts of brass and 1 of zinc; the latter being added to the former, previously brought into a state of fusion. The crucible must be immediately covered up for two minutes till the combination be completed. The melted alloy is to be then poured out upon a bundle of twigs held over a tub of water, into which it falls in granulations. An alloy of 3 parts of copper and 1 of zinc forms a still stronger solder for the coppersmiths. When several parts are to be soldered successively upon the same piece, the more fusible alloys, containing more zinc, should be used first. A softer solder for coppersmiths is made with 6 parts of brass, 1 of tin, and 1 of zinc; the tin being first added to the melted brass, then the zinc; and the whole well incorporated by stirring.

The edges of sheet lead for sulphuric acid chambers, and its concentration pans, are joined together by melted lead itself, because any solder containing tin would soon be corroded. With this view, the two edges being placed in contact, are flattened down into a long wooden groove, and secured in their situation by a few brass pins driven into the wood. The surfaces are next brightened with a triangular scraper, rubbed over with candle grease, and then covered with a stream of hot melted lead. The riband of lead thus applied is finally equalized by being brought into partial fusion with the plumber’s conical iron heated to redness; the contact of air being prevented by sprinkling rosin over the surface. The sheets of lead are thus _burned_ together, in the language of the workmen.

SOOT (_Noir de fumée_, _Suie_, Fr.; _Rus_, _Flatterrus_, Germ.); is the pulverulent charcoal condensed from the smoke of wood or coal fuel. A watery infusion of the former is said to be antiseptic, probably from its containing some creosote.

The soot of pitcoal has not been analyzed with any minuteness. It contains some sulphate and carbonate of ammonia, along with bituminous matter.

SORBIC ACID, is the same with malic acid; which see.

SOY, is a liquid condiment, or sauce, imported chiefly from China. It is prepared with a species of white haricots, wheat flour, common salt, and water; in the proportions respectively of 50, 60, 50, and 250 pounds. The haricots are washed, and boiled in water till they become so soft as to yield to the fingers. They are then laid in a flat dish to cool, and kneaded along with the flour, a little of the hot water of the decoction being added from time to time. This dough is next spread an inch or an inch and a half thick upon the flat vessel (made of thin staves of bamboo), and when it becomes hot and mouldy, in two or three days, the cover is raised upon bits of stick, to give free access of air. If a rancid odour is exhaled, and the mass grows green, the process goes on well; but if it grows black, it must be more freely exposed to the air. As soon as all the surface is covered with green mouldiness, which usually happens in eight or ten days, the cover is removed, and the matter is placed in the sunshine for several days. When it has become as hard as a stone, it is cut into small fragments, thrown into an earthen vessel, and covered with the 250 pounds of water having the salt dissolved in it. The whole is stirred together, and the height at which the water stands is noted. The vessel being placed in the sun, its contents are stirred up every morning and evening; and a cover is applied at night, to keep it warm and exclude rain. The more powerful the sun, the sooner the soy will be completed; but it generally requires two or three of the hottest summer months. As the mass diminishes by evaporation, well water is added; and the digestion is continued till the salt water has dissolved the whole of the flour and the haricots; after which the vessel is left in the sun for a few days, as the good quality of the soy depends on the completeness of the solution, which is promoted by regular stirring. When it has at length assumed an oily appearance, it is poured into bags, and strained. The clear black liquid is the soy, ready for use. It is not boiled, but is put up into bottles, which must be carefully corked. Genuine soy was made in this way at Canton, by Michael de Grubbens. See _Memoirs of Academy of Sciences of Stockholm_ for 1803.

SPECIFIC GRAVITY, designates the relative weights of different bodies under the same bulk; thus a cubic foot of water weighs 1000 ounces avoirdupois; a cubic foot of coal, 1350; a cubic foot of cast iron, 7280; a cubic foot of silver, 10,400; and a cubic foot of pure gold, 19,200; numbers which represent the specific gravities of the respective substances, compared to water = 1·000. See ALLOY.

SPECULUM METAL, is an alloy of copper and tin; described under COPPER.

SPERMACETI; the _Cetine_ of Chevreul. In certain species of the _cachalot_ whale, as the _Physeter macrocephalus_, _tursio_, _microps_, and _orthodon_, as also the _Delphinus edentulus_, the fat of some parts of their bodies contains a peculiar kind of stearine, called spermaceti. The oil obtained from cavities in the bones of the cranium of the above cetaceæ is the richest in this kind of stearine. This being thrown into great filter-bags, the spermaceti oil passes through, and is subsequently purified by the addition of a small quantity of potash lye, which precipitates certain matters by neutralizing the acid that held them in solution. The solid which remains on the filter is next squeezed in bags, by means of a horizontal hydraulic press encased in steam, then digested with a weak potash lye, in order to dissolve out any oil which may continue to adhere to it, washed with water, finally dissolved in a tub by the agency of steam, laded into tin pans, and allowed slowly to concrete into a white semi-transparent brittle lamellar crystalline mass, which forms elegant candles.

At 60° its specific gravity is 0·943. It melts at 112·5°; 100 parts of alcohol at 0·821 dissolve 3-1/2 of it, of which 0·9 are deposited on cooling. Warm ether dissolves it in very large quantities. It is soluble also in the fat of volatile oils; and if the solutions have been saturated while hot, the greater part of the spermaceti crystallizes on cooling. When this substance has been purified by digesting alcohol upon it repeatedly, what remains is the _cetine_ of Chevreul, or pure spermaceti. Its melting point has now become 116° F., and its boiling point 616° F., at which it distils without alteration. Caustic alkaline lyes saponify it with difficulty.

SPIRIT OF AMMONIA, is, properly speaking, alcohol combined with ammonia gas; but the term is often applied to water of ammonia.

SPIRITS, VINOUS. This subject has been fully discussed in the articles ALCOHOL, DISTILLATION, and FERMENTATION. I have shown that the progressive increase of alcohol in the wash tends progressively to prevent the conversion of the wort into spirit, or checks the fermenting process, though a great deal of fermentable matter remains unchanged. Mr. Sheridan has sought to remove this obstacle to the thorough transmutation of saccharine matter into alcohol, by drawing off the spirit as it is formed. For this purpose he ferments his wash in close tuns, connected with a powerful air-pump worked by machinery, thus continually removing the carbonic acid as it is formed, and maintaining a diminished pressure under which the alcohol readily distils at a temperature of 120° or 130° F. He finds that this degree of heat is not injurious to the fermentation, provided that it be communicated by the air of a stove-room, and not by water or steam pipes traversing the liquid, which would inevitably scald or seeth the particles in succession, and thereby extinguish the fermenting principle.

By the above ingenious plan, Mr. Sheridan tells me he has obtained 28 gallons of proof spirit from a quarter of grain, instead of the average product 21, being an increase of 25 per cent. The experiment was tried upon a considerable scale at Messrs. Currie’s great distillery near London; but could not be established as a mode of manufacture, on account of the excise laws, which prohibit the distillers from carrying on the two processes of fermentation and distillation at the same time.

SPIRIT OF WINE; Alcohol.

SPONGE (_Eponge_, Fr.; _Schwamm_, Germ.); is a cellular fibrous tissue produced by small animals, almost imperceptible, called polypi by naturalists, which live in the sea. This tissue is said to be covered in its recent state with a kind of semi-fluid thin coat of animal jelly, susceptible of a slight contraction or trembling on being touched; which is the only symptom of vitality displayed by the sponge. After death, this jelly disappears, and leaves merely the sponge; formed by the combination of a multitude of small capillary tubes, capable of receiving water in their interior, and of becoming thereby distended. Sponges occur attached to stones at the bottom of the sea; and abound particularly upon the shores of the islands in the Grecian Archipelago. Although analogous in their origin to coral, sponges are quite different in their nature; the former being composed almost entirely of carbonate of lime; while the latter are formed of the same elements as animal matters, and afford, on distillation, a considerable quantity of ammonia.

Dilute sulphuric acid has been recommended for bleaching sponges, after the calcareous impurities have been removed by muriatic acid. Chlorine water answers better.

SPOON MANUFACTURE. See STAMPING OF METALS.

STAINED GLASS. When certain metallic oxides or chlorides, ground up with proper fluxes, are painted upon glass, their colours fuse into its surface at a moderate heat, and make durable pictures, which are frequently employed in ornamenting the windows of churches as well as of other public and private buildings. The colours of stained glass are all transparent, and are therefore to be viewed only by transmitted light. Many metallic pigments, which afford a fine effect when applied cold on canvas or paper, are so changed by vitreous fusion as to be quite inapplicable to painting in stained glass.

The glass proper for receiving these vitrifying pigments, should be colourless, uniform, and difficult of fusion; for which reason crown glass, made with little alkali, or with kelp, is preferred. When the design is too large to be contained on a single pane, several are fitted together, and fixed in a bed of soft cement while painting, and then taken asunder to be separately subjected to the fire. In arranging the glass pieces, care must be taken to distribute the joinings so that the lead frame-work may interfere as little as possible with the effect.

A design must be drawn upon paper, and placed beneath the plate of glass; though the artist cannot regulate his tints directly by his pallet, but by specimens of the colours producible from his pallet pigments after they are fired. The upper side of the glass being sponged over with gum-water, affords, when dry, a surface proper for receiving the colours, without the risk of their running irregularly, as they would be apt to do, on the slippery glass. The artist first draws on the plate, with a fine pencil, all the traces which mark the great outlines and shades of the figures. This is usually done in black, or, at least, some strong colour, such as brown, blue, green, or red. In laying on these, the painter is guided by the same principles as the engraver, when he produces the effect of light and shade by dots, lines, or hatches; and he employs that colour to produce the shades, which will harmonize best with the colour which is to be afterwards applied; but for the deeper shades, black is in general used. When this is finished, the whole picture will be represented in lines or hatches similar to an engraving finished up to the highest effect possible; and afterwards, when it is dry, the vitrifying colours are laid on by means of larger hair pencils; their selection being regulated by the burnt specimen tints. When he finds it necessary to lay two colours adjoining, which are apt to run together in the kiln, he must apply one of them to the back of the glass. But the few principal colours to be presently mentioned, are all fast colours, which do not run, except the yellow, which must therefore be laid on the opposite side. After colouring, the artist proceeds to bring out the lighter effects by taking off the colour in the proper place, with a goose quill cut like a pen without a slit. By working this upon the glass, he removes the colour from the parts where the lights should be the strongest; such as the hair, eyes, the reflection of bright surfaces and light parts of draperies. The blank pen may be employed either to make the lights by lines, or hatches and dots, as is most suitable to the subject.

By the metallic preparations now laid upon it, the glass is made ready for being fired, in order to fix and bring out the proper colours. The furnace or kiln best adapted for this purpose, is similar to that used by enamellers. See ENAMEL, and the _Glaze-kiln_; under POTTERY. It consists of a muffle or arch of fire-clay or pottery, so set over a fireplace, and so surrounded by flues, as to receive a very considerable heat within, in the most equable and regular manner; otherwise some parts of the glass will be melted; while, on others, the superficial film of colours will remain unvitrified. The mouth of the muffle, and the entry for introducing fuel to the fire, should be on opposite sides, to prevent as much as possible the admission of dust into the muffle, whose mouth should be closed with double folding-doors of iron, furnished with small peep-holes, to allow the artist to watch the progress of the staining, and to withdraw small trial slips of glass, painted with the principal tints used in the picture.

The muffle must be made of very refractory fire-clay, flat at its bottom, and only 5 or 6 inches high, with such an arched top as may make the roof strong, and so close on all sides as to exclude entirely the smoke and flame. On the bottom of the muffle a smooth bed of sifted lime, freed from water, about half an inch thick, must be prepared for receiving the pane of glass. Sometimes several plates of glass are laid over each other with a layer of dry pulverulent lime between each. The fire is now lighted, and most gradually raised, lest the glass should be broken; and after it has attained to its full heat, it must be kept up for 3 or 4 hours, more or less, according to the indications of the trial slips; the yellow colour being principally watched, as it is found to be the best criterion of the state of the others. When the colours are properly burnt in, the fire is suffered to die away, so as to anneal the glass.

STAINED-GLASS PIGMENTS.

_Flesh colour._--Take an ounce of red lead, two ounces of red enamel (Venetian glass enamel, from alum and copperas calcined together), grind them to fine powder, and work this up with spirits (alcohol) upon a hard stone. When slightly baked, this produces a fine flesh colour.

_Black colour._--Take 14-1/2 ounces of smithy scales of iron, mix them with two ounces of white glass (crystal), an ounce of antimony, and half an ounce of manganese; pound and grind these ingredients together with strong vinegar. A brilliant black may also be obtained by a mixture of cobalt blue with the oxides of manganese and iron. Another black is made from three parts of crystal glass, two parts of oxide of copper, and one of (glass of) antimony worked up together, as above.

_Brown colour._--An ounce of white glass or enamel, half an ounce of good manganese; ground together.

_Red, rose, and brown colours_, are made from peroxide of iron, prepared by nitric acid. The flux consists of borax, sand, and minium in small quantity.

_Red colour_, may be likewise obtained from one ounce of red chalk pounded, mixed with two ounces of white hard enamel, and a little peroxide of copper.

_A red_, may also be composed of rust of iron, glass of antimony, yellow glass of lead, such as is used by potters (or litharge), each in equal quantity; to which a little sulphuret of silver is added. This composition, well ground, produces a very fine red colour on glass. When protoxide of copper is used to stain glass, it assumes a bright red or green colour, according as the glass is more or less heated in the furnace, the former corresponding to the orange protoxide, the latter having the copper in the state of peroxide.

_Bistres and brown reds_, may be obtained by mixtures of manganese, orange oxide of copper, and the oxide of iron called umber, in different proportions. They must be previously fused with vitreous solvents.

_Green colour._--Two ounces of brass calcined into an oxide, two ounces of minium, and eight ounces of white sand; reduce them to a fine powder, which is to be enclosed in a well luted crucible, and heated strongly in an air-furnace for an hour. When the mixture is cold, grind it in a brass mortar. Green may, however, be advantageously produced by a yellow on one side, and a blue on the other. Oxide of chrome has been also employed to stain glass green.

_A fine yellow colour._--Take fine silver laminated thin, dissolve in nitric acid, dilute with abundance of water, and precipitate with solution of sea salt. Mix this chloride of silver, in a dry powder, with three times its weight of pipe-clay well burnt and pounded. The back of the glass pane is to be painted with this powder; for when painted on the face, it is apt to run into the other colours.

_Another yellow_ can be made by mixing sulphuret of silver with glass of antimony, and yellow ochre previously calcined to a red-brown tint. Work all these powders together, and paint on the back of the glass. Or silver _laminæ_ melted with sulphur, and glass of antimony, thrown into cold water, and afterwards ground to powder, afford a yellow.

_A pale yellow_ may be made with the powder resulting from brass, sulphur, and glass of antimony, calcined together in a crucible, till they cease to smoke; and then mixed with a little burnt yellow ochre.

_The fine yellow_ of M. Merand, is prepared from chloride of silver, oxide of zinc, white-clay, and rust of iron. This mixture, simply ground, is applied on the glass.

_Orange colour._--Take 1 part of silver powder, as precipitated from the nitrate of that metal by plates of copper, and washed; mix it with 1 part of red ochre and 1 of yellow, by careful trituration; grind into a thin pap with oil of turpentine or lavender, and apply this with a brush, dry, and burn in.

In the Philosophical Magazine, of December, 1836, the anonymous author of an ingenious essay, “On the Art of Glass-painting,” says, that if a large proportion of ochre has been employed with the silver, the stain is yellow; if a small proportion, it is orange-coloured; and by repeated exposure to the fire, without any additional colouring-matter, the orange may be converted into red; but this conversion requires a nice management of the heat. Artists often make use of panes coloured throughout their substance in the glass-house pots, because the perfect transparency of such glass gives a brilliancy of effect, which enamel painting, always more or less opaque, cannot rival. It was to a glass of this kind that the old glass-painters owed their splendid red. This is, in fact, the only point in which the modern and antient processes differ; and this is the only part of the art which was ever really lost. Instead of blowing plates of solid red, the old glass-makers (like those of Bohemia, for some time back,) used to _flash_ a thin layer of brilliant red over a substratum of colourless glass; by gathering a lump of the latter upon the end of their iron rod in one pot, covering it with a layer of the former in another pot, then blowing out the two together into a globe or cylinder, to be opened into circular tables, or into rectangular plates. The elegant art of tinging glass red by protoxide of copper, and flashing it on common crown glass, has become general within these few years.

That gold melted with flint glass stains it purple, was originally discovered and practised, as a profitable secret, by Kunckel. Gold has been recently used at Birmingham for giving a beautiful rose-colour to scent bottles. The proportion of gold should be very small, and the heat very great, to produce a good effect. The glass must contain either the oxide of lead, bismuth, zinc, or antimony; for crown glass will take no colour from gold. Glass combined with this metal, when removed from the crucible is generally of a pale rose-colour; nay, sometimes is as colourless as water, and does not assume its ruby colour till it has been exposed to a low red heat, either under a muffle or at the lamp. This operation must be nicely regulated; because a slight excess of fire destroys the colour, leaving the glass of a dingy brown, but with a blue (green?) transparency, like that of gold leaf. It is metallic gold which gives the colour; and, indeed, the oxide is too easily reduced, not to be converted into the metal by the intense heat which is necessarily required.

Upon the kindred art of painting in enamel, Mr. A. Essex has published an interesting paper in the same journal, for June, 1837, in which he says that the antient ruby glass, on being exposed to the heat of a glass-kiln, preserves its colour unimpaired, while the modern suffers considerable injury, and in some cases becomes almost black. Hence the latter cannot be painted upon, as the heat required to fix the fresh colour would destroy the beauty of the original basis. To obviate this difficulty, the artist paints upon a piece of plain glass the tints and shadows necessary for blending the rich ruby glow with the other parts of his picture, leaving those parts untouched where he wishes the ruby to appear in undiminished brilliancy, and fixes the ruby glass in the picture behind the painted piece, so that in such parts, the window is double-glazed. Mr. Essex employs, as did the late Mr. Muss, chrome oxide alone for greens; and he rejects the use of iron and manganese in his enamel colours.

Coloured transparent glass is applied as enamel in silver and gold _bijouterie_, previously _bright-cut_ in the metal with the graver or the rose-engine. The cuts, reflecting the rays of light from their numerous surfaces, exhibit through the glass, richly stained with gold, silver, copper, cobalt, &c., a gorgeous play of prismatic colours, varied with every change of aspect. When the enamel is to be painted on, it should be made opalescent by oxide of arsenic, in order to produce the most agreeable effect.

The artist in enamel has obtained from modern chemistry, preparations of the metals platinum, uranium, and chromium, which furnish four of the richest and most useful colours of his palette. Oxide of platinum produces a substantive rich brown, formerly unknown in enamel painting; a beautiful transparent tint, which no intensity or repetition of firing can injure. Colours proper for enamel painting, he says, are not to be purchased; those sold for the purpose, are adapted only for painting upon china. The constituents of the green enamel used by his brother, Mr. W. Essex, are, silica, borax, oxide of lead, and oxide of chrome.

Mr. Essex’s enamelling furnace is a cubic space of about 12 inches, and contains a fire-clay muffle, without either bottom or back, which is surrounded with coke, except in front. The entire draught of air which supplies the furnace, passes through the muffle; the plates and paintings being placed on a thin slab, made of tempered fire-clay, technically termed _planche_, which rests on the bed of coke-fuel. As the greatest heat is at the back of the muffle, the picture must be turned round while in the fire, by means of a pair of spring tongs. The above furnace serves for objects up to five inches in diameter; but for larger works a different furnace is required, for the description of which I must refer to the original paper.

Relatively to the receipts for enamel colours, and for staining and gilding on glass, for which twenty guineas were voted by the Society for the Encouragement of Arts, in the session of 1817, to Mr. R. Wynn, Mr. A. Essex says, in p. 446. of his essay--“the unfortunate artist who shall attempt to make colours for the purpose of painting in enamel from these receipts, will assuredly find, to his disappointment, that they are utterly useless.” In page 449. he institutes a comparison between Mr. Wynn’s complex _farrago_ for green, as published in the Transactions of the Society, with the simple receipt of his brother, as given above. It is a remarkable circumstance, that not one of our enamel artists, during a period of twenty years, should have denounced the fallacy of these receipts, and the folly of sanctioning imposture by a public reward. Should Mr. Essex’s animadversions be just, the well-intentioned Society in the Adelphi may, from the negligence of its committee, come to merit the _sobriquet_, “For the Discouragement of Arts.”

STAMPING OF METALS. The following ingenious machine for manufacturing metal spoons, forks, and other articles, was made the subject of a patent by Jonathan Hayne, of Clerkenwell, in May, 1833. He employs a stamping-machine with dies, in which the hammer is raised to a height between guides, and is let fall by a trigger. He prefers fixing the protuberant or relief portion of the die to the stationary block or bed of the stamping-machine, and the counterpart or intaglio to the falling hammer or ram.

The peculiar feature of improvement in this manufacture consists in producing the spoon, ladle, or fork perfect at one blow in the stamping-machine, and requiring no further manipulation of shaping, but simply trimming off the barb or fin, and polishing the surface, to render the article perfect and finished.

Heretofore, in employing a stamping-machine, or fly-press, for manufacturing spoons, ladles, and forks, it has been the practice to give the impressions to the handles, and to the bowls or prongs, by distinct operations of different dies, and after having so partially produced the pattern upon the article, the handles had to be bent and formed by the operations of filing and hammering.

By his improved form of dies, which, having curved surfaces and bevelled edges, allow of no parts of the faces of the die and counter-die to come into contact, he is enabled to produce considerable elevations of pattern and form, and to bring up the article perfect at one blow, with only a slight barb or fin upon its edge.

In the accompanying drawings, _fig._ 1042. is the lower or bed die for producing a spoon, seen edgewise; _fig._ 1043. is the face of the upper or counter-die, corresponding; _fig._ 1044. is a section, taken through the middle of the pair of dies, showing the space in which the metal is pressed to form the spoon.

To manufacture spoons, ladles, or forks according to his improved process, he first forges out the ingot into flat pieces, of the shape and dimensions of the die of the intended article; and if a spoon or ladle is to be made, gives a slight degree of concavity to the bowl part; but, if necessary, bends the back, in order that it may lie more steadily, and bend more accurately, upon the lower die; if a fork, he cuts or otherwise removes portions of the metal at those parts which will intervene between the prongs; and, having thus produced the rude embryo of the intended article, scrapes its entire surface clean and free from oxidation-scale or fire-strain, when it is ready to be introduced into the stamping-machine.

He now fixes the lower die in the bed of the stamping-machine, shown at _a_, _a_, in the elevations _figs._ 1045. and 1046., and fixes, in the hammer _b_, the upper or counter-die _c_, accurately adjusting them both, so that they may correspond exactly when brought together. He then places the rudely-formed article above described upon the lower die, and having drawn up the hammer to a sufficient elevation by a windlass and rope, or other ordinary means, lets go the trigger, and allows the hammer with the counter-die to fall upon the under die, on which the article is placed; when, by the blow thus given to the metal, the true and perfect figure and pattern of the spoon, ladle, or fork is produced, and which, as before said, will only require the removal of the slight edging of barb or fin, with polishing, to finish it.

On striking the blow, in the operation of stamping the article, the hammer will recoil and fly up some distance, and if allowed to fall again with reiterated blows, would injure both the article and the dies; therefore, to avoid this inconvenience, he causes the hammer on recoiling to be caught by a pair of palls locking into racks on the face of the standards, seen in _figs._ 1045. and 1046. In _fig._ 1045. the hammer _b_, of the stamping-machine, is seen raised and suspended by a rope attached to a pair of jointed hooks or holders _d_, _d_, the lower ends of which pass into eyes _e_, _e_, extending from the top of the hammer. When the lever or trigger _t_ is drawn forward, as in _fig._ 1046., the two inclined planes _g_, _g_, on the axle _h_, press the two legs of the holders _d_, _d_, inward, and cause their hooks or lower ends to be withdrawn from the eyes _e_, _e_, when the hammer instantly falls, and brings the dies together: such is the ordinary construction of the stamping-machine.

On the hammer falling from a considerable elevation, the violence of the blow causes it to recoil and bound upwards, as before mentioned; it therefore becomes necessary to catch the hammer when it has rebounded, in order to prevent the dies coming again together; this is done by the following mechanism:--

Two latch levers _i_, _i_, are connected by joints to the upper part of the hammer, and two pall levers _k_, _k_, turning upon pins, are mounted in the bridge _l_, affixed to the hammer. Two springs _m_, _m_, act against the lower arms of these levers, and press them outwards, for the purpose of throwing the palls at the lower ends of the levers into the teeth of the ratchet racks _n_, _n_, fixed on the sides of the upright standards.

Previously to raising the hammer, the upper ends of the pall levers _k_, are drawn back, and the latches _i_, being brought down upon them, as in _fig._ 1045., the levers _k_ are confined, and their palls prevented from striking into the side racks; but as the hammer falls, the ends of the latches _i_ strike upon the fingers _o_, _o_, fixed to the side standards, and liberate the palls, the lower ends of which, when the hammer rebounds, after stamping, catch into the teeth of the racks, as in _fig._ 1046., and thereby prevent the hammer from again descending.

STARCH; (_Amidon_, _Fecule_, Fr.; _Stärke_, Germ.); is a white pulverulent substance, composed of microscopic spheroids, which are bags containing the amylaceous matter. It exists in a great many different plants, and varies merely in the form and size of its microscopic particles; as found in some plants, it consists of spherical particles 1/1000 of an inch in diameter; and in others, of ovoid particles, of 1/300 or 1/400 of an inch. It occurs, 1. in the seeds of all the acotyledinous plants, among which are the several species of corns, and those of other _gramineæ_; 2. in the round perennial tap roots, which shoot up an annual stem; in the tuberose roots, such as potatos, the _Convolvulus batatas_ and _edulis_, the _Helianthus tuberosus_, the _Jatropha manihot_, &c., which contain a great quantity of it; 3. in the stems of several monocotyledinous plants, especially of the palm tribe, whence sago comes; but it is very rarely found in the stems and branches of the dicotyledinous plants; 4. it occurs in many species of lichen. Three kinds of starch have been distinguished by chemists; that of wheat, that called _inuline_, and lichen starch. These three agree in being insoluble in cold water, alcohol, ether, and oils, and in being converted into sugar by either dilute sulphuric acid or diastase. The main difference between them consists in their habitudes with water and iodine. The first forms with hot water a mucilaginous solution, which constitutes, when cold, the paste of the laundress, and is tinged blue by iodine; the second forms a granular precipitate, when its solution in boiling-hot water is suffered to cool, which is tinged yellow by iodine; the third affords, by cooling the concentrated solution, a gelatinous mass, with a clear liquor floating over it, that contains little starch. Its jelly becomes brown-gray with iodine.

1. _Ordinary starch._--This may be extracted from the following grains:--wheat, rye, barley, oats, buckwheat, rice, maize, millet, spelt; from the siliquose seeds, as peas, beans, lentiles, &c.; from tuberous and tap roots, as those of the potato, the orchis, manioc; arrowroot, batata, &c. Different kinds of corn yield very variable quantities of starch. Wheat differs in this respect, according to the varieties of the plant, as well as the soil, manure, season, and climate. See BREAD.

Wheat partly damaged by long keeping in granaries, may be employed for the manufacture of starch, as this constituent suffers less injury than the gluten; and it may be used either in the ground or unground state.

1. _With unground wheat._--The wheat being sifted clean, is to be put into cisterns, covered with soft water, and left to steep till it becomes swollen and so soft as to be easily crushed between the fingers. It is now to be taken out, and immersed in clear water of a temperature equal to that of malting-barley, whence it is to be transferred into bags, which are placed in a wooden chest containing some water, and exposed to strong pressure. The water rendered milky by the starch being drawn off by a tap, fresh water is poured in, and the pressure is repeated. Instead of putting the swollen grain into bags, some prefer to grind it under vertical edge-stones, or between a pair of horizontal rollers, and then to lay it in a cistern, and separate the starchy liquor by elutriation with successive quantities of water well stirred up with it. The residuary matter in the sacks or cisterns contains much vegetable albumen and gluten, along with the husks; when exposed to fermentation, it affords a small quantity of starch of rather inferior quality.

The above milky liquor, obtained by expression or elutriation, is run into large cisterns, where it deposits its starch in layers successively less and less dense; the uppermost containing a considerable proportion of gluten. The supernatant liquor being drawn off, and fresh water poured on it, the whole must be well stirred up, allowed again to settle, and the surface-liquor again withdrawn. This washing should be repeated as long as the water takes any perceptible colour. As the first turbid liquor contains a mixture of gluten, sugar, gum, albumen, &c., it ferments readily, and produces a certain portion of vinegar, which helps to dissolve out the rest of the mingled gluten, and thus to bleach the starch. It is, in fact, by the action of this fermented or soured water, and repeated washing, that it is purified. After the last deposition and decantation, there appears on the surface of the starch a thin layer of a slimy mixture of gluten and albumen, which, being scraped off, serves for feeding pigs or oxen; underneath will be found a starch of good quality. The layers of different sorts are then taken up with a wooden shovel, transferred into separate cisterns, where they are agitated with water, and passed through fine sieves. After this pap is once more well settled, the clear water is drawn off, the starchy mass is taken out, and laid on linen cloths in wicker baskets, to drain and become partially dry. When sufficiently firm, it is cut into pieces, which are spread upon other cloths, and thoroughly desiccated in a proper drying-room, which in winter is heated by stoves. The upper surface of the starch is generally scraped, to remove any dusty matter, and the resulting powder is sold in that state. Wheat yields, upon an average, only from 35 to 40 per cent. of good starch. It should afford more by skilful management.

2. In this country, wheat crushed between iron rollers is laid to steep in as much water as will wet it thoroughly; in four or five days the mixture ferments, soon afterwards settles, and is ready to be washed out with a quantity of water into the proper fermenting vats. The common time allowed for the steep, is from 14 to 20 days. The next process consists in removing the stuff from the vats into a stout round basket set across a back below a pump. One or two men keep going round the basket, stirring up the stuff with strong wooden shovels, while another keeps pumping water, till all the _farina_ is completely washed from the bran. Whenever the subjacent back is filled, the liquor is taken out and strained through hair sieves into square frames or cisterns, where it is allowed to settle for 24 hours; after which the water is run off from the deposited starch by plug taps at different levels in the side. The thin stuff, called _slimes_, upon the surface of the starch, is removed by a tray of a peculiar form. Fresh water is now introduced, and the whole being well mixed by proper agitation, is then poured upon fine silk sieves. What passes through is allowed to settle for 24 hours; the liquor being withdrawn, and then the slimes, as before, more water is again poured in, with agitation, when the mixture is again thrown upon the silk sieve. The milky liquor is now suffered to rest for several days, 4 or 5, till the starch becomes settled pretty firmly at the bottom of the square cistern. If the starch is to have the blue tint, called Poland, fine smalt must be mixed in the liquor of the last sieve, in the proportion of 2 or 3 lbs. to the cwt. A considerable portion of these slimes may, by good management, be worked up into starch by elutriation and straining.

The starch is now fit for _boxing_, by shovelling the cleaned deposit into wooden chests, about 4 feet long, 12 inches broad, and 6 inches deep, perforated throughout, and lined with thin canvas. When it is drained and dried into a compact mass, it is turned out by inverting the chests upon a clean table, where it is broken into pieces 4 or 5 inches square, by laying a ruler underneath the cake, and giving its surface a cut with a knife, after which the slightest pressure with the hand will make the fracture. These pieces are set upon half-burned bricks, which by their porous capillarity imbibe the moisture of the starch, so that its under surface may not become hard and horny. When sufficiently dried upon the bricks, it is put into a stove (which resembles that of a sugar refinery), and left there till tolerably dry. It is now removed to a table, when all the sides are carefully scraped with a knife; it is next packed up in the papers in which it is sold; these packages are returned into the stove, and subjected to a gentle heat during some days; a point which requires to be skilfully regulated.

Mr. Samuel Hall obtained a patent for bleaching starch by chloride of lime in 1821. Chlorine water would probably be preferable, and might prove useful in operating upon damaged wheat.

The sour water of the starch manufacture contains, according to Vauquelin, acetic acid, acetate of ammonia, alcohol, phosphate of lime, and gluten.

During the drying, starch splits into small prismatic columns, of considerable regularity. When kept dry, it remains unaltered for a very long period. When it is heated to a certain degree in water, the envelopes of its spheroidal particles burst, and the _farina_ forms a mucilaginous emulsion, magma, or paste. When this apparent solution is evaporated to dryness, a brittle horny-looking substance is obtained, quite different in aspect from starch, but similar in chemical habitudes. When the moist paste is exposed for 2 or 3 months to the air in summer, the starch is converted into sugar to the amount of one-third or one-half of its weight, into gum, and gelatinous starch called _amidine_ by De Saussure, with occasionally a resinous matter. This curious change goes on even in close vessels.

_Starch from potatos._--From the following table of analyses, it appears that potatos contain from 24 to 30 per cent. of dry substance:--

+-------------------+-------+-----------+--------+-----------+------+ | | | Fibrous | Veg. |Gum, Sugar,| | | |Starch.|parenchyma.|Albumen.|and Salts. |Water.| +-------------------+-------+-----------+--------+-----------+------+ |Red potato | 15·0 | 7·0 | 1·4 | 9·2 | 75·0 | |Germinating potatos| 15·2 | 6·8 | 1·3 | 3·7 | 73·0 | |Kidney potatos | 9·1 | 8·8 | 0·8 | --- | 81·3 | |Large red potatos | 12·9 | 6·0 | 0·7 | --- | 78·0 | |Sweet potatos | 15·1 | 8·2 | 0·8 | --- | 74·3 | |Peruvian potatos | 15·0 | 5·2 | 1·9 | 1·9 | 76·0 | |English potatos | 12·9 | 6·8 | 1·1 | 1·7 | 77·5 | |Parisian potatos | 13·3 | 6·8 | 0·9 | 4·8 | 73·1 | +-------------------+-------+-----------+--------+-----------+------+

_Manufacture of potato starch._--The potatos are first washed in a cylindrical cage formed of wooden spars, made to revolve upon a horizontal axis, in a trough filled with water to the level of the axis. They are then reduced to a pulp by a rasping machine, similar to that represented in _figs._ 1047, 1048., where _a_ is a wooden drum covered with sheet-iron, roughened outside with numerous prominences, made by punching out holes from the opposite side. It is turned by a winch fixed upon each end of the shaft. The drum is enclosed in a square wooden box, to prevent the potato-mash from being scattered about. The hopper _b_ is attached to the upper frame, has its bottom concentric with the rasp-drum, and nearly in contact with it. The pulp chest _c_ is made to slide out, so as when full to be readily replaced by another. The two slanting boards _d_, _d_, conduct the pulp into it. A moderate stream of water should be made to play into the hopper upon the potatos, to prevent the surface of the rasp from getting foul with fibrous matter. Two men, with one for a relay, will rasp, with such a machine, from 2-1/2 to 3 tons of potatos in 12 hours.

The potato pulp must be now elutriated upon a fine wire or hair sieve, which is set upon a frame in the mouth of a large vat, while water is made to flow upon it from a spout with many jets. The pulp meanwhile must be stirred and kneaded by the hand, or by a mechanical brush-agitator, till almost nothing but fibrous particles are left upon the sieve. These, however, generally retain about 5 per cent. of starch, which cannot be separated in this way. This parenchyma should therefore be subjected to a separate rasping upon another cylinder. The water turbid with starch is allowed to settle for some time in a back; the supernatant liquor is then run by a cock into a second back, and after some time into a third, whereby the whole starch will be precipitated. The finest powder collects in the last vessel. The starch thus obtained, containing 33 per cent. of water, may be used either in the moist state, under the name of _green fecula_, for various purposes, as for the preparation of dextrine, and starch syrup; or it may be preserved under a thin layer of water, which must be renewed from time to time, to prevent fermentation; or lastly, it may be taken out and dried.

In trials made with St. Etienne’s rasp and starch machinery, in Paris, which was driven by two horses, nearly 18 cwt. of potatos were put through all the requisite operations in one hour, including the pumping of the water. The product in starch amounted to from 17 to 18 per cent. of the potatos. The quicker the process of potato-starch making, the better is its quality.

_Starch from certain foreign plants._--1. From the pith of the _sago palm_. See SAGO.

2. From the roots of the _Maranta arundinacea_, of Jamaica, the Bahamas, and other West India islands, the powder called arrow-root is obtained, by a process analogous to that for making potato starch.

3. From the root of the _Manioc_, which also grows in the West Indies, as well as in Africa, the _cassava_ is procured, by a similar process. The juice of this plant is poisonous, from which the wholesome starch is deposited. When dried with stirring upon hot iron plates, it agglomerates into small lumps, called _tapioca_; being a gummy fecula.

The characters of the different varieties of starch can be learnt only from microscopic observation; by which means also their sophistication or admixture may be readily ascertained.

Starch, from whatever source obtained, is a white soft powder, which feels crispy, like flowers of sulphur, when pressed between the fingers; it is destitute of taste and smell, unchangeable in the atmosphere, and has a specific gravity of 1·53. I have already described the particles as spheroids enclosed in a membrane. The potato contains some of the largest, and the millet the smallest. Potato starch consists of truncated ovoids, varying in size from 1/300 to 1/3000 of an inch; arrow-root, of ovoids varying in size from 1/800 to 1/2000 of an inch; flower starch, of insulated globules about 1/1000 of an inch; cassava, of similar globules assembled in groups. These measurements I have made with a good achromatic microscope, and a divided glass-slip micrometer of Tully.

For the saccharine changes which starch undergoes by the action of _diastase_, see FERMENTATION.

_Lichenine_, a species of starch obtained from Iceland moss (_Cetraria islandica_), as well as _inuline_, from elecampane (_Inula Helenium_), are rather objects of chemical curiosity, than of manufactures.

There is a kind of starch made in order to be converted into gum for the calico-printer. This conversion having been first made upon the great scale in this country, has occasioned the product to be called British gum. The following is the process pursued in a large and well conducted establishment near Manchester. A range of four wooden cisterns, each about 7 or 8 feet square, and 4 feet deep, is provided. Into each of them 2000 gallons of water being introduced, 12-1/2 loads of flour are stirred in. This mixture is set to ferment upon old leaven left at the bottom of the backs, during 2 or 3 days. The contents are then stirred up, and pumped off into 3 stone cisterns, 7 feet square and 4 feet deep; as much water being added, with agitation, as will fill the cisterns to the brim. In the course of 24 hours the starch forms a firm deposit at the bottom; and the water is then syphoned off. The gluten is next scraped from the surface, and the starch is transferred into wooden boxes pierced with holes, which may be lined with coarse cloth, or not, at the pleasure of the operator.

The starch, cut into cubical masses, is put into iron trays, and set to dry in a large apartment, two stories high, heated by a horizontal cylinder of cast-iron traversed by the flame of a furnace. The drying occupies two days. It is now ready for conversion into gum, for which purpose it is put into oblong trays of sheet iron, and heated to the temperature of 300° F. in a cast-iron oven, which holds four of these trays. Here it concretes into irregular semi-transparent yellow-brown lumps, which are ground into fine flour between mill-stones, and in this state brought to the market. In this roasted starch, the vesicles being burst, their contents become soluble in cold water. British gum is not convertible into sugar, as starch is, by the action of dilute sulphuric acid; nor into mucic acid, by nitric acid; but into the oxalic; and it is tinged purple-red by iodine. It is composed, in 100 parts, of 35·7 carbon, 6·2 hydrogen, and 58·1 oxygen; while starch is composed of, 43·5 carbon, 6·8 hydrogen, and 49·7 oxygen.

To prove whether starch be quite free from gluten, or whether it be mixed with any wheat flour, diffuse 12 grains of it through six ounces of water, heat the mixture to boiling, stirring it meanwhile with a glass slip. If the starch be pure, no froth will be seen upon the surface of the pasty fluid; or if any be produced during the stirring, it will immediately subside after it; but if the smallest portion of gluten be present, much froth will be permanently formed, which may be raised by stirring into the appearance of soap-suds.

STARCHING AND STEAM-DRYING APPARATUS. The system of hollow cylinders, for drying goods in the processes of bleaching or calico-printing, is represented in _fig._ 1049. in a longitudinal section, and in _fig._ 1050. in a top view; but the cylinders are supposed to be broken off in the middle, as it was needless to repeat the parts at the other end, which are sufficiently shown in the section.

A is the box containing the paste, when the goods are to be starched or stiffened: _a_, a winch, when it is desired to turn the machine by hand, though it is always moved by power in considerable factories; _b_, is the driving pinion; _d_, _d´_, two brass rollers with iron shafts, the undermost of which is moved by the wheel _c_, in geer with the pinion _b_. The uppermost roller _d´_, is turned by the friction with the former, _d_, being pressed upon it by the weighted lever _h_; _e_ is the trough filled with the paste, which rests upon the bars _f_, and may be placed higher or lower by means of the adjusting screws _g_, according as the roller _d_ is to be plunged more or less deeply. A brass roller _i_ serves to force down the cloth into the paste.

B, is the drying part of the machine: _k_, _k_, its iron framing; _l_, _l_, &c., five drums, or hollow copper cylinders, heated with steam: _m_, _m_, _m_, &c., small copper drums, in pairs, turning freely on shafts under the former, for stretching the goods, and airing them, during their passage through the machine: _n_, _n_, is the main steam-pipe, from which branch off small copper tubes, _o_, _o_, &c., which conduct the steam through stuffing-boxes into the cavity of the drying-drums. There are similar tubes upon the other ends of the drums, for discharging the condensed water through similar stuffing-boxes: _q_, _q_, are valves, opening internally, for admitting the air whenever the steam is taken _off_, or becomes feeble, to prevent the drums from being crushed by the unbalanced pressure of the atmosphere upon their external surfaces.

C, is the cloth-beam, from which the starching roller draws forward the goods; _d_, _d_, are two rollers, of which the lower is provided with a band-pulley or rigger, driven by a similar pulley fixed upon the shaft of the starching roller _d_. These two rollers pull the goods through the drying machine, and then let them fall either upon a table or the floor.

STEAM, is the vapour of hot water; the discussion of which belongs to chemistry, physics, and engineering. Certain practical applications of the subject will be found in the article EVAPORATION.

STEARIC ACID, improperly called STEARINE (_Talgsaüre_, Germ.), is the solid constituent of fatty substances, as of tallow and olive oil, converted into a crystalline mass by saponification with alkaline matter, and abstraction of the alkali by an acid. By this process, fats are convertible into three acids, called Stearic, Margaric, and Oleic; the first two being solid, and the last liquid. The stearine, of which _factitious wax_ candles are made, consists of the stearic and margaric acids combined. These can be separated from each other only by the agency of alcohol, which holds the margaric acid in solution after it has deposited the stearic in crystals. Pure stearic acid is prepared, according to its discoverer, Chevreul, in the following way:--Make a soap, by boiling a solution of potash and mutton-suet in the proper equivalent proportions (see SOAP); dissolve one part of that soap in 6 parts of hot water, then add to the solution 40 or 50 parts of cold water, and set the whole into a place whose temperature is about 52° Fahrenheit. A substance falls to the bottom, possessed of pearly lustre, consisting of the bi-stearate and bi-margarate of potash; which is to be drained and washed upon a filter. The filtered liquor is to be evaporated, and mixed with the small quantity of acid necessary to saturate the alkali left free by the precipitation of the above bi-salts. On adding water to it afterwards, the liquor affords a fresh quantity of bi-stearate and bi-margarate. By repeating this operation with precaution, we finally arrive at a point when the solution contains no more of these solid acids, but only the oleic. The precipitated bi-salts are to be washed and dissolved in hot alcohol, of specific gravity 0·820, of which they require about 24 times their weight. During the cooling of the solution, the bi-stearate falls down, while the greater part of the bi-margarate, and the remainder of the oleate, remain dissolved. By once more dissolving in alcohol, and crystallizing, the bi-stearate will be obtained alone; as may be proved by decomposing a little of it in water at a boiling heat, with muriatic acid, letting it cool, washing the stearic acid obtained, and exposing it to heat, when, if pure, it will not fuse in water under the 158th degree of Fahrenheit’s scale. If it melts at a lower heat, it contains more or less margaric acid. The purified bi-stearate being decomposed by boiling in water along with any acid, as the muriatic, the disengaged stearic acid is to be washed by melting in water, then cooled and dried.

Stearic acid, prepared by the above process, contains combined water, from which it cannot be freed. It is insipid and inodorous. After being melted by heat, it solidifies at the temperature of 158° Fahrenheit, and affects the form of white brilliant needles grouped together. It is insoluble in water, but dissolves in all proportions in boiling anhydrous alcohol, and on cooling to 122°, crystallizes therefrom, in pearly plates; but if the concentrated solution be quickly cooled to 112°, it forms a crystalline mass. A dilute solution affords the acid crystallized in large white brilliant scales. It dissolves in its own weight of boiling ether of 0·727, and crystallizes on cooling in beautiful scales, of changing colours. It distils over _in vacuo_ without alteration; but if the retort contains a little atmospheric air, a small portion of the acid is decomposed during the distillation; while the greater part passes over unchanged, but slightly tinged brown, and mixed with traces of empyreumatic oil. When heated in the open air, and kindled, stearic acid burns like wax. It contains 3·4 per cent. of water, from which it may be freed by combining it with oxide of lead. When this anhydrous acid is subjected to ultimate analysis, it is found to consist of--80 of carbon, 12·5 hydrogen, and 7·5 oxygen, in 100 parts. Stearic acid displaces, at a boiling heat in water, carbonic acid from its combinations with the bases; but in operating upon an alkaline carbonate, a portion of the stearic acid is dissolved in the liquor before the carbonic acid is expelled. This decomposition is founded upon the principle, that the stearic acid transforms the salt into a bicarbonate, which is decomposed by the ebullition.

Stearic acid put into a strong watery infusion of litmus, has no action upon it in the cold; but when hot, the acid combines with the alkali of the litmus, and changes its blue colour to red; so that it has sufficient energy to abstract from the concentrated tincture all the alkali required for its neutralization. If we dissolve bi-stearate of potash in weak alcohol, and pour litmus water, drop by drop, into the solution, this will become red, because the litmus will give up its alkali to a portion of the bi-stearate, and will convert it into neutral stearate. If we now add cold water, the reddened mixture will resume its blue tint, and will deposit bi-stearate of potash in small spangles. In order that the alcoholic solution of the bi-stearate may redden the litmus, the alcohol should not be very strong.

From the composition of stearate of potash, the atomic weight of the acid appears to be 106·6; hydrogen being 1; for 18 : 48 × 2 ∷ 100 : 533·3 = 5 atoms of acid.

From the stearate of soda, it appears to be 104; and from that of lime, 102. The stearate of lead, by Chevreul, gives 109 for the atomic weight of the acid.

The margaric and oleic acids seem to have the same neutralizing power, and the same atomic weight.

The preceding numbers will serve to regulate the manufacture of stearic acid for the purpose of making candles. Potash and soda were first prescribed for saponifying fat, as may be seen in M. Gay Lussac’s patent, under the article CANDLE; and were it not for the cost of these articles, they are undoubtedly preferable to all others in a chemical point of view. Of late years lime has been had recourse to, with perfect success, and has become subservient to a great improvement in candle-making. The stearine block now made by many London houses, though containing not more than 2 or 3 per cent. of wax, is hardly to be distinguished from the purified produce of the bee. The first process is to boil the fat with quicklime and water in a large tub, by means of perforated steam pipes distributed over its bottom. From the above statements we see that about 11 parts of dry lime are fully equivalent to 100 of stearine and oleine mixed: but as the lime is in the state of hydrate, 14 parts of it will be required when it is perfectly pure; in the ordinary state, however, as made from average good limestone, 16 parts may be allowed. After a vigorous ebullition of 3 or 4 hours, the combination is pretty complete. The stearate being allowed to cool to such a degree as to allow of its being handled, becomes a concrete mass, which must be dug out with a spade, and transferred into a contiguous tub, in order to be decomposed with the equivalent quantity of sulphuric acid diluted with water, and also heated with steam. Four parts of concentrated acid will be sufficient to neutralize three parts of slaked lime. The saponified fat now liberated from the lime, which is thrown down to the bottom of the tub in the state of sulphate, is skimmed off the surface of the watery menstruum into a third contiguous tub, where it is washed with water and steam.

The washed mixture of stearic, margaric, and oleic acids, is next cooled in tin pans; then shaved by large knives, fixed on the face of a fly-wheel, called a tallow cutter, preparatory to its being subjected in canvas or caya bags to the action of a powerful hydraulic press. Here a large portion of the oleic acid is expelled, carrying with it a little of the margaric. The pressed cakes are now subjected to the action of water and steam once more, after which the supernatant stearic acid is run off, and cooled in moulds. The cakes are then ground by a rotatory rasping-machine to a sort of mealy powder, which is put into canvas bags, and subjected to the joint action of steam and pressure in a horizontal hydraulic press of a peculiar construction, somewhat similar to that which has been long used in London for pressing spermaceti. The cakes of stearic acid thus freed completely from the margaric and oleic acids, are subjected to a final cleansing in a tub with steam, and then melted into hemispherical masses called blocks. When these blocks are broken, they display a highly crystalline texture, which would render them unfit for making candles. This texture is therefore broken down or comminuted by fusing the stearine in a plated copper pan, along with one thousandth part of pulverized arsenious acid, after which it is ready to be cast into candles in appropriate moulds. See CANDLE.

STEARINE COLD PRESS. The cold hydraulic press, as mounted by Messrs. Maudslay and Field, for squeezing out the oleic acid from saponified fat, or the oleine from coco-nut lard, is represented in plan in _fig._ 1051.; in side view of pump in _fig._ 1052.; and in elevation, _fig._ 1053.; where the same letters refer to like objects.

A, A, are two hydraulic presses; B the frame; C, the cylinder; D, the piston or ram; E, the follower; F, the recess in the bottom to receive the oil; G, twilled woollen bags with the material to be pressed, having a thin plate of wrought iron between each; H, apertures for the discharge of the oil; I, cistern in which the pumps are fixed; K, framing for machinery to work in; L, two pumps, large and small, to inject the water into the cylinders; M, a frame containing three double branches; N, three branches, each having two stops or plugs, by which the action of one of the pumps may be intercepted from, or communicated to, one or both of the presses; the large pump is worked at the beginning of the operation, and the small one towards the end; by these branches, one or both presses may be discharged when the operation is finished; O, two pipes from the pumps to the branches; P, pipe to return the water from the cylinders to the cisterns; Q, pipes leading from the pumps through the branches to the cylinders; R, conical drum, fixed upon the main shaft Y, driven by the steam-engine of the factory; S, a like conical drum to work the pumps; T, a narrow leather strap to communicate the motion from R to S; U, a long screw bearing a nut, which works along the whole length of the drum; V, the fork or guide for moving the strap T; W, W, two hanging bearings to carry the drum S; X, a pulley on the spindle of the drum S; Y, the main shaft; Z, fly-wheel with groove on the edge, driven by the pulley X; on the axis of S, is a double crank, which works the two pumps L. _a_, is a pulley on the end of the long screw U; an endless cord passes twice round this pulley, and under a pulley fixed in the weight _b_; by laying hold of both sides of his cord, and raising or lowering it, the forked guide V, and the leather strap T, are moved backwards or forwards, by means of the nut fixed in the guide, so as to accelerate or retard at pleasure the speed of the working of the pumps; _c_, is a piece of iron, with a long slit, in which a pin, attached to the fork V, travels, to keep it in the vertical position.

STEATITE (_Soapstone_; _Craie de Briançon_, Fr.; _Speckstein_, Germ.); is a mineral of the magnesian family. It has a grayish-white or greenish-white colour, often marked with dendritic delineations, and occurs massive, as also in various supposititious crystalline forms; it has a dull or fatty lustre; a coarse splintery fracture, with translucent edges; a shining streak; it writes feebly; is soft, and easily cut with a knife; but somewhat tough; does not adhere to the tongue; feels very greasy; infusible before the blowpipe; specific gravity from 2·6 to 2·8. It consists of--silica, 44; magnesia, 44; alumina, 2; iron, 7·3; manganese, 1·5; chrome, 2; with a trace of lime. It is found frequently in small contemporaneous veins that traverse serpentine in all directions, as at Portsoy, in Shetland, in the limestone of Icolmkiln, in the serpentine of Cornwall, in Anglesey, in Saxony, Bavaria (at Bayruth), Hungary, &c. It is used in the manufacture of porcelain. It makes the biscuit semi-transparent, but rather brittle, and apt to crack with slight changes of heat. It is employed for polishing serpentine, marble, gypseous alabaster, and mirror glass; as the basis of cosmetic powders; as an ingredient in anti-attrition pastes; it is dusted in powder upon the inside of boots, to make the feet glide easily into them; when rubbed upon grease-spots in silk and woollen clothes, it removes the stains by absorption; it enters into the composition of certain crayons, and is used itself for making traces upon glass, silk, &c. The spotted steatite, cut into cameos and calcined, assumes an onyx aspect. Soft steatite forms excellent stoppers for the chemical apparatus used in distilling or subliming corrosive vapours. Lamellar steatite is TALC.

STEEL (_Acier_, Fr.; _Stahl_, Germ.); as a carburet of iron, has already been considered under that metal. I shall treat in this article more particularly of its manufacture and technical relations.

1. _Steel of cementation, bar or blistered steel._--With the exception of the Ulverstone charcoal iron, no bars are manufactured in Great Britain capable of conversion into steel at all approaching in quality to that made from the Madras, Swedish, and Russian irons, so largely imported for that purpose. The first rank is assigned to the Swedish iron stamped with a circle enclosing the letter L (hence called hoop L); which fetches the high price of 36_l._ 10_s._ per ton, while excellent English coke-iron may be had for one-fifth of the price. The other Swedish irons are sold at a much lower rate, though said to be manufactured in the same way; and therefore the superiority of the Dannemora iron must be owing to some peculiarity in the ore from which it is smelted. The steel recently made in the Indian steel-works at Chelsea, from Mr. Heath’s Madras iron, rivals that from the hoop L.

The Sheffield furnace for making bar or blistered steel, called the furnace of cementation, is represented in _fig._ 1054. in a cross section, and in _fig._ 1055. in a ground plan. The hearth of this oblong quadrangular furnace, is divided by a grate into two parts, upon each side of which there is a chest _a_, called a _trough_, made of fire-clay, or fire-tiles. The breadth of the grate varies according to the quality of the fuel. _b_, _b_, are air-holes; _c_, _c_, flues leading to the chimney _d_, _d_. To aid the draught of the smoke and the flame, an opening _e_, is made in the middle of the flat arch of the furnace. In one of its shorter sides (ends), there are orifices _f_, _f_, through which the long bars of iron may be put in and taken out; _g_, is the door by which the steel-maker enters, in filling or emptying the trough; _h_, is a proof hole, at which small samples of the steel, in the act of its conversion, may be drawn out. The furnace is built under a conical hood or chimney, from 30 to 50 feet high, for aiding the draught, and carrying off the smoke.

The two chests are built of fire-stone grit. They are 8, 10, or even 15 feet long, and from 26 to 36 inches in width and depth; the lower and smaller they are, the more uniform will the quality of the steel be. A great breadth and height of trough are incompatible with equability of the cementing temperature. The sides are a few inches thick. The space between them is at least a foot wide. They should never rest directly upon the sole of the furnace, but must have their bottom freely played upon by the flame, as well as the sides and top. The degree of heat is regulated by openings in the arch, or upon the long sides of the furnace, which lead to the chimney; as also by the greater or less quantity of air admitted below the grate, as in glass-house furnaces.

The _cement_ consists of ground charcoal (sometimes of soot), mixed with one-tenth of ashes, and some common salt; the charcoal of hard wood being preferred. Ground coke is inadmissible, on account of the sulphur, silica, and clay which it generally contains. Possibly the salt serves to vitrify the particles of silica in the charcoal, and thus to prevent their entering into combination with the steel. As for the ashes, it is difficult to discover their use. The best steel may be made without their presence. The bottom of the trough being covered with two inches of the powder of cementation, the bars are laid along in it, upon their narrow edge, the side bar being one inch from the trough, and the rest being from 1/2 to 3/4 of an inch apart. Above this first layer of iron bars, fully half an inch depth of the powder is spread, then a new series of bars is stratified, and so on till the trough is filled within six inches of the top. This space is partially filled with old cement powder, and is covered with refractory damp sand. Sometimes the trough is filled to the surface with the old cement, and then closely covered with fire-tiles. The bars should never be allowed to touch each other, or the trough. The fire must be carefully urged from 2 to 4 days, till it acquires the temperature of 100° Wedgewood; which must be steadily maintained during the 4, 6, 8, or 10 days requisite for the cementation; a period dependent on the size of the furnace, and which is determined by the examination of the proof pieces, taken out from time to time.

In the front or remote end of the furnace, _fig._ 1054., a door is left in the outer building, corresponding to a similar one in the end of the interior vault, through which the workman enters for charging the furnace with charcoal and iron bars, as also for taking out the steel after the conversion. Small openings are likewise made in the ends of the chests, through which the extremities of a few bars are left projecting, so that they may be pulled out and examined, through small doors opposite to them in the exterior walls. These _tap_ holes, as they are called, should be placed near the centre of the end stones of the chests, that the bars may indicate the average state of the process. The joinings of the fire-stones are secured with a finely ground Stourbridge clay.

The interval between the two chests (in furnaces containing two, for many have only one,) being covered with an iron platform, the workman stands on it, and sifts a layer of charcoal on the bottom of the chests evenly, about half an inch thick; he then lays a row of bars, cut to the proper length, over the charcoal, about an inch from each other; he next sifts on a second stratum of charcoal-dust, which, as it must serve for the bars above, as well as below, is made an inch thick; thus, he continues to stratify, till the chest be filled within two inches of the top; and he covers the whole with the earthy detritus found at the bottom of grindstone troughs, or any convenient fire-loam. It is obvious that the second series of bars should correspond vertically with the interstices between the first series, and so in succession. The trial-rods are left longer than the others, and their projecting ends are encrusted with fire-clay, or imbedded in sand. The iron platform being removed, and all the openings into the vault closed, the fire is lighted, and very gradually increased, to avoid every risk of cracking the gritstone by too sudden a change of temperature; and the ignition being finally raised to about 100° Wedgewood, but not higher, for fear of melting the metal, must be maintained at a uniform pitch, till the iron have absorbed the desired quantity of carbon, and have been converted as highly as the manufacturer intends for his peculiar object. From six to eight days may be reckoned a sufficient period for the production of steel of moderate hardness, and fit for tilting into shear steel. A softer steel, for saws and springs, takes a shorter period; and a harder steel, for fabricating chisels used in cutting iron, will need longer exposure to the ignited charcoal. But, for a few purposes, such as the bits for boring cast iron, the bars are exposed to two or three successive processes of cementation, and are hence said to be twice or thrice converted into steels. The higher the heat of the furnace, the quicker is the process of conversion.

The furnace being suffered to cool, the workman enters it again, and hands out the steel bars, which being covered with blisters, from the formation and bursting of vesicles on the surface filled with gaseous carbon, is called _blistered steel_. This steel is very irregular in its interior texture, has a white colour, like frosted silver, and displays crystalline angles and facettes, which are larger the further the cementation has been urged, or the greater the dose of carbon. The central particles are always smaller than those near the surface of the bar.

In such a furnace as the above, twelve tons of bar iron may be converted at a charge. But other furnaces are constructed with one chest, which receives six or eight tons at a time; the small furnaces, however, consume more fuel in proportion than the larger.

The absorption and action of the carbonaceous matter, to the amount of about a half per cent., occasions fissures and cavities in the substance of the blistered bars, which render the steel unfit for any useful purpose in tool-making, till it be condensed and rendered uniform by the operation of _tilting_, under a powerful hammer driven by machinery. See IRON.[59]

[59] For minute details of the parts, see the excellent article TILTING-HAMMER, in _Rees’s Cyclopædia_.

The heads of the tilt-hammers for steel weigh from one and a half to two hundred pounds. Those in the neighbourhood of Sheffield are much simpler than the one referred to in the note. They are worked by a small water-wheel, on whose axis is another wheel, bearing a great number of cams or wipers on its circumference, which strike the tail of the hammer in rapid succession, raise its head, and then let it fall smartly on the hot metal rod, dexterously presented on its several parts to the anvil beneath it, by the workman. The machinery is adapted to produce from 300 to 400 blows per minute; which on this plan requires an undue and wasteful velocity of the float-boards. Were an intermediate toothed wheel substituted between the water-wheel and the wiper-wheel, so that while the former made one turn, the latter might make three, a much smaller force of water would do the work. The anvils of the tilt-hammer are placed nearly on a level with the floor of the mill-house; and the workman sits in a fosse, dug on purpose, in a direction perpendicular to the line of the helve, on a board suspended from the roof of the building by a couple of iron rods. On this swinging seat, he can advance or retire with the least impulse of his feet, pushing forward the steel bar, or drawing it back with equal rapidity and convenience.

At a small distance from each tilt, stands the forge-hearth, for heating the steel. The bellows for blowing the fire are placed above-head, and are worked by a small crank fixed on the end of the axis of the wheel, the air being conveyed by a copper pipe down to the nozzle. Each workman at the tilt has two boys in attendance, to serve him with hot rods, and to take them away after they are hammered. In small rods, the bright ignition originally given at the forge soon declines to darkness; but the rapid impulsions of the tilt revive the redness again in all the points near the hammer; so that the rod, skilfully handled by the workman, progressively ignites where it advances to the strokes. Personal inspection alone can communicate an adequate idea of the precision and celerity with which a rude steel rod is stretched and fashioned into an even, smooth, and sharp-edged prism, under the operation of the tilt-hammer. The heat may be clearly referred to the prodigious friction among the particles of so cohesive a metal, when they are made to slide so rapidly over each other in every direction during the elongation and squaring of the rod.

2. _Shear steel_ derives its name from the accidental circumstance of the shears for dressing woollen cloth being usually forged from it. It is made by binding into a bundle, with a slender steel rod, four parallel bars of blistered steel, previously broken into lengths of about 18 inches, including a fifth of double length, whose projecting end may serve as a handle. This faggot, as it is called, is then heated in the forge-hearth to a good welding heat, being sprinkled over with sand to form a protecting film of iron slag, carried forthwith to the tilt, and notched down on both sides to unite all the bars together, and close up every internal flaw or fissure. The mass being again heated, and the binding rings knocked off, is drawn out into a uniform rod of the size required. Manufacturers of cutlery are in the habit of purchasing the blistered bars at the conversion furnaces, and sending them to tilt-mills to have them drawn out to the proper size, which is done at regular prices to the trade; from 5 to 8 per cent. discount being allowed on the rude bars for waste in the tilting. The metal is rendered so compact by the welding and hammering, as to become susceptible of a much finer polish than blistered steel can take; while the uniformity of its body, tenacity, and malleability are at the same time much increased; by which properties it becomes well adapted for making table knives and powerful springs, such as those of gun-locks. The steel is also softened down by this process, probably from the expulsion of a portion of its carbon during the welding and subsequent heats; and if these be frequently or awkwardly applied, it may pass back into common iron.

3. _Cast steel_ is made by melting, in the best fire-clay crucibles, blistered steel, broken down into small pieces of convenient size for packing; and as some carbon is always dissipated in the fusion, a somewhat highly converted steel is used for this purpose. The furnace is a square prismatic cavity, lined with fire-bricks, 12 inches in each side, and 24 deep, with a flue immediately under the cover, 3-1/2 inches by 6, for conducting the smoke into an adjoining chimney of considerable height. In some establishments a dozen such furnaces are constructed in one or two ranges, their tops being on a level with the floor of the laboratory, as in brass-foundries, for enabling the workmen more conveniently to inspect, and lift out, the crucibles with tongs. The ash-pits terminate in a subterraneous passage, which supplies the grate with a current of cool air, and serves for emptying out the ashes. The crucible, stands of course, on a sole-piece of baked fire-clay; and its mouth is closed with a well-fitted lid. Sometimes a little bottle-glass, or blast-furnace slag, is put into the crucible, above the steel pieces, to form a vitreous coating, that may thoroughly exclude the air from oxidizing the metal. The fuel employed in the cast-steel furnace is a dense coke, brilliant and sonorous, broken into pieces about the size of an egg, one good charge of which is sufficient. The tongs are furnished at the fire end with a pair of concave jaws, for embracing the curvature of the crucible, and lifting it out whenever the fusion is complete. The lid is then removed, the slag or scoriæ cleared away, and the liquid metal poured into cast-iron octagonal or rectangular moulds, during which it throws out brilliant scintillations.

Cast-steel works much harder under the hammer than shear steel and will not, in its usual state, bear much more than a cherry-red heat without becoming brittle; nor can it bear the fatigue incident to the welding operation. It may, however, be firmly welded to iron, through the intervention of a thin film of vitreous boracic acid, at a moderate degree of ignition. Cast steel, indeed, made from a less carburetted bar steel, would be susceptible of welding and hammering at a higher temperature; but it would require a very high heat for its preparation in the crucible.

Iron may be very elegantly plated with cast steel, by pouring the liquid metal from the crucible into a mould containing a bar of iron polished on one face. In this circumstance the adhesion is so perfect as to admit of the two metals being rolled out together; and in this way the chisels of planes and other tools may be made, at a moderate rate and of excellent quality, the cutting-edge being formed in the steel side. Such instruments combine the toughness of iron with the hardness of steel.

For correcting the too high carbonization of steel, or equalizing the too highly converted exterior of a bar with the softer steel of the interior, the metal requires merely to be imbedded, at a cementing heat, in oxide of iron or manganese; the oxygen of which soon abstracts the injurious excess of carbon, so that the outer layers may be even converted into soft iron, while the axis continues steely; because the decarbonizing advances far more rapidly than the carbonizing.

_Fig._ 1056. represents the mould for making crucibles for the cast-steel works. M, M, is a solid block of wood, to support the two-handled outside mould N, N. This being rammed full of the proper clay dough or compost (see CRUCIBLE), the inner mould is to be then pressed vertically into it, till it reaches the bottom P, being directed and facilitated in its descent by the point _K_. A cord passes through O, by which the inner mould is suspended over a pulley, and guided in its motions.

When a plate of polished steel is exposed to a progressive heat, it takes the following colours in succession: 1. a faint yellow; 2. a pale straw-colour; 3. a full yellow; 4. a brown yellow; 5. a brown with purple spots; 6. a purple; 7. a bright blue; 8. a full blue; 9. a dark blue, verging on black; after which the approach to ignition supersedes all these colours. If the steel plate has been previously hardened by being dipped in cold water or mercury when red-hot, then those successive shades indicate or correspond to successive degrees of softening or tempering. Thus, No. 1. suits the hard temper of a lancet, which requires the finest edge, but little strength of metal; No. 2. a little softer, for razors and surgeons’ amputating instruments; No. 3. somewhat more toughness, for penknives; No. 4. for cold chisels and shears for cutting iron; No. 5. for axes and plane-irons; No. 6. for table knives and cloth shears; No. 7. for swords and watch springs; No. 8. for small fine saws and daggers; No. 9. for large saws, whose teeth need to be set with pliers, and sharpened with a file. After ignition, if the steel be very slowly cooled, it becomes exceedingly soft, and fit for the engraver’s purposes. Hardened steel may be tempered to the desired pitch, by plunging it in metallic baths heated to the proper thermometric degree, as follows: for No. 1. 430° Fahr.; No. 2. 450°; No. 3. 470°; No. 4. 490°; No. 5. 510°; No. 6. 530°; No. 7. 550°; No. 8. 560°; No. 9. 600°.

Small steel tools are most frequently tempered, after hardening, by covering their surface with a thin coat of tallow, and heating them in the flame of a candle till the tallow diffuses a faint smoke, and then thrusting them into the cold tallow. Rinman long ago defined steel to be any kind of iron which, when heated to redness, and then plunged in cold water, becomes harder. But several kinds of cast iron are susceptible of such hardening. Every malleable and flexible iron, however, which may be hardened in that way, is a steel. Moreover, steel may be distinguished from pure iron by its giving a dark-gray spot when a drop of dilute nitric acid is let fall on its surface, while iron affords a green one. Exposed to the air, steel rusts less rapidly than iron; and the more highly carburetted, the more slowly does it rust, and the blacker is the spot left by an acid.

After hardening, steel seems to be quite a different body; even its granular texture becomes coarser or finer according to the degree of heat to which it was raised; it grows so hard as to scratch glass, and resist the keenest file, while it turns exceedingly brittle. When a slowly cooled steel rod is forged and filed, it becomes capable of affording agreeable and harmonious sounds by its vibrations; but hard-tempered steel affords only dull deafened tones, like those emitted by a cracked instrument.

The good quality of steel is shown by its being homogeneous; being easily worked at the forge; by its hardening and tempering well; by its resisting or overcoming forces; and by its elasticity. To ascertain the first point, the surface should be ground and polished on the wheel; when its lustre and texture will appear. The second test requires a skilful workman to give it a heat suitable to its nature and state of conversion. The size and colour of the grain are best shown by taking a bar forged into a razor form; hardening and tempering it; and then breaking off the thin edge in successive bits with a hammer and anvil. If it had been fully ignited only at the end, then, after the hardening, it will display, on fracture, a succession in the aspect of its grains from that extremity to the other; as they are whiter and larger at the former than the latter. The other qualities become manifest on filing the steel; using it as a chisel for cutting iron; or bending it under a heavy weight.

Much interest was excited a few years back by the experiments of Messrs. Stodart and Faraday on the alloys of steel with silver, platinum, rhodium, and iridium. Steel refuses to take up in fusion more than one five-hundreth part of silver; but with this minute quantity of alloy, it is said to bear a harder temper, without losing its tenacity. When pure iron is substituted for steel, the alloys so formed are much less subject to oxidation in damp air than before. With three _per cent._ of iridium and osmium, an alloy was obtained which had the property of tempering like steel, and of remaining clean and bright, in circumstances when simple iron became covered with rust. “Upon the whole,” says the editor of the Quarterly Journal of Science, giving a report of these experiments in his 14th volume, p. 378, “though we consider these researches upon the alloys of steel as very interesting, we are not sanguine as to their important influence upon the improvement of the manufacture of cutlery, and suspect that a bar of the best ordinary steel, selected with precaution, and most carefully forged, wrought, and tempered, _under the immediate inspection of the master_, would afford cutting instruments as perfect and excellent as those composed of wootz, or of the alloys.”

_Case-hardening_ of iron, is a process for converting a thin film of the outer surface into steel, while the interior remains as before. Fine keys are generally finished in this way. See CASE-HARDENING.

So great is the affinity of iron for carbon, that, in certain circumstances, it will absorb it from carburetted hydrogen, or coal-gas, and thus become converted into steel. On this principle, Mr. Macintosh of Glasgow obtained a patent for making steel. His furnace consists of one cylinder of bricks built concentrically within another. The bars of iron are suspended in the innermost, from the top; a stream of purified coal-gas circulates freely round them, entering below and escaping slowly above, while the bars are maintained in a state of bright ignition by a fire burning in the annular space between the cylinders. The steel so produced is of excellent quality; but the process does not seem to be so economical as the ordinary cementation with charcoal powder.

_Damasking of steel_, is the art of giving to sabre blades a variety of figures in the style of watering. See DAMASCUS BLADES.

Several explanations have been offered of the change in the constitution of steel, which accompanies the tempering operation; but none of them seems quite satisfactory. It seems to be probable that the ultimate molecules are thrown by the sudden cooling into a constrained state, so that their poles are not allowed to take the position of strongest attraction and greatest proximity; and hence the mass becomes hard, brittle, and somewhat less dense. An analogous condition may be justly imputed to hastily cooled glass, which, like hardened steel, requires to be annealed by a subsequent nicely graduated heat, under the influence of which the particles assume the position of repose, and constitute a denser, softer, and more tenacious body. The more sudden the cooling of ignited steel, the more unnatural and constrained will be the distribution of its particles, and also the more refractory, an effect produced by plunging it into cold mercury. This excess of hardness is removed in any required degree by judicious annealing or tempering. The state of the carbon present in the steel may also be modified by the rate of refrigeration, as Mr. Karsten and M. Bréant conceive happens with cast iron and the damask metal. If the uniform distribution and combination of the carbon through the mass, determine the peculiarity of white cast iron, which is a hard and brittle substance, and if its transition to the dark-gray and softer cast metal be effected by a partial formation of plumbago during slow cooling, why may not something similar be supposed to occur with steel, an analogous compound?

Mr. Oldham, printing engineer of the Bank of England, who has had great experience in the treatment of steel for dies and mills, says that, for hardening it, the fire should never be heated above the redness of sealing-wax, and kept at that pitch for a sufficient time. On taking it out, he hardens it by plunging it, not in water, but in olive oil, or rather naphtha, previously heated to 200° F. It is kept immersed only till the ebullition ceases, then instantly transferred into cold spring water, and kept there till quite cold. By this treatment the tools come out perfectly clean, and as hard as it is possible to make cast-steel, while they are perfectly free from cracks, flaws, or twist. Large tools are readily brought down in temper by being suspended in the red-hot muffle till they show a straw-colour; but for small tools, he prefers plunging them in the oil heated to 400 degrees; and leaves them in till they become cold.

Mr. Oldham softens his steel dies by exposing them to ignition for the requisite time, imbedded in a mixture of chalk and charcoal.

“The common mode of softening steel,” says Mr. Baynes, “is to put it into an iron case, surrounded with a paste made of lime, cow’s gall, and a little nitre and water; then to expose the case to a slow fire, which is gradually increased to a considerable heat, and afterwards allowed to go out, when the steel is found to be soft and ready for the engraver.”[60]

[60] History of the Cotton Manufacture, p. 269. If that strange farrago be employed by Mr. Locket of Manchester, for softening his dies and mills, it deserves consideration. Should the nitre be used in too great quantity to be all carbonated by the gall, its oxygen may serve to consume some of the carbon of the steel, and thus bring it nearer to iron. The recipe may be old, but it is a novelty to me.

_Indian steel, or wootz._--The wootz ore consists of the magnetic oxide of iron, united with quartz, in proportions which do not seem to differ much, being generally about 42 of quartz and 58 of magnetic oxide. Its grains are of various size, down to a sandy texture. The natives prepare it for smelting by pounding the ore, and winnowing away the stony matrix, a task at which the Hindoo females are very dexterous. The manner in which iron ore is smelted and converted into wootz or Indian steel, by the natives at the present day, is probably the very same that was practised by them at the time of the invasion of Alexander; and it is a uniform process, from the Himalaya mountains to Cape Comorin. The furnace or bloomery in which the ore is smelted, is from 4 to 5 feet high; it is somewhat pear-shaped, being about 2 feet wide at bottom, and one foot at top; it is built entirely of clay, so that a couple of men can finish its erection in a few hours, and have it ready for use the next day. There is an opening in front about a foot or more in height, which is built up with clay at the commencement, and broken down at the end, of each smelting operation. The bellows are usually made of a goat’s skin, which has been stripped from the animal without ripping open the part covering the belly. The apertures at the legs are tied up, and a nozzle of bamboo is fastened in the opening formed by the neck. The orifice of the tail is enlarged and distended by two slips of bamboo. These are grasped in the hand, and kept close together in making the stroke for the blast; in the returning stroke they are separated to admit the air. By working a bellows of this kind with each hand, making alternate strokes, a pretty uniform blast is produced. The bamboo nozzles of the bellows are inserted into tubes of clay, which pass into the furnace at the bottom corners of the temporary wall in front. The furnace is filled with charcoal, and a lighted coal being introduced before the nozzles, the mass in the interior is soon kindled. As soon as this is accomplished, a small portion of the ore, previously moistened with water, to prevent it from running through the charcoal, but without any flux whatever, is laid on the top of the coals, and covered with charcoal to fill up the furnace.

In this manner ore and fuel are supplied; and the bellows are urged for 3 or 4 hours, when the process is stopped; and the temporary wall in front being broken down, the bloom is removed by a pair of tongs from the bottom of the furnace. It is then beaten with a wooden mallet, to separate as much of the scoriæ as possible from it, and, while still red-hot, it is cut through the middle, but not separated, in order merely to show the quality of the interior of the mass. In this state it is sold to the blacksmiths, who make it into bar iron. The proportion of such iron made by the natives from 100 parts of ore, is about 15 parts. In converting the iron into steel, the natives cut it into pieces, to enable it to pack better in the crucible, which is formed of refractory clay, mixed with a large quantity of charred husk of rice. It is seldom charged with more than a pound of iron, which is put in with a proper weight of dried wood chopped small, and both are covered with one or two green leaves; the proportions being in general 10 parts of iron to 1 of wood and leaves. The mouth of the crucible is then stopped with a handful of tempered clay, rammed in very closely, to exclude the air. The wood preferred is the _Cassia auriculata_, and the leaf that of the _Asclepias gigantea_, or the _Convolvulus laurifolius_. As soon as the clay plugs of the crucibles are dry, from 20 to 24 of them are built up in the form of an arch, in a small blast furnace; they are kept covered with charcoal, and subjected to heat urged by a blast for about two hours and a half, when the process is considered to be complete. The crucibles being now taken out of the furnace and allowed to cool, are broken, and the steel is found in the form of a cake, rounded by the bottom of the crucible. When the fusion has been perfect, the top of the cake is covered with striæ, radiating from the centre, and is free from holes and rough projections; but if the fusion has been imperfect, the surface of the cake has a honeycomb appearance, with projecting lumps of malleable iron. On an average, four out of five cakes are more or less defective. These imperfections have been tried to be corrected in London by re-melting the cakes, and running them into ingots; but it is obvious, that when the cakes consist partially of malleable iron and of unreduced oxide, simple fusion cannot convert them into good steel. When care is taken, however, to select only such cakes as are perfect, to re-melt them thoroughly, and tilt them carefully into rods, an article has been produced which possesses all the requisites of fine steel in an eminent degree. In the Supplement to the Encyclopædia Britannica, article _Cutlery_, the late Mr. Stodart, of the Strand, a very competent judge, has declared “that for the purposes of fine cutlery, it is infinitely superior to the best English cast steel.”

The natives prepare the cakes for being drawn into bars by annealing them for several hours in a small charcoal furnace, actuated by bellows; the current of air being made to play upon the cakes while turned over before it; whereby a portion of the combined carbon is probably dissipated, and the steel is softened; without which operation the cakes would break in the attempt to draw them. They are drawn by a hammer of a few pounds weight.

The natives weld two pieces of cast steel, by giving to each a sloping face, jagged all over with a small chisel; then applying them with some calcined borax between, and tying them together with a wire, they are brought to a full red heat, and united by a few smart blows of a hammer.

The ordinary bar iron of Sweden and England, when converted by cementation into steel, exhibits upon its surface numerous small warty points, but few or no distinct vesicular eruptions; whereas the Dannemora and the Ulverston steels present, all over the surface of the bars, well raised blisters, upwards of three-eighths of an inch in diameter horizontally, but somewhat flattened at top. Iron of an inferior description, when highly converted in the cementing-chest, becomes gray on the outer edges of the fracture; while that of Dannemora acquires a silvery colour and lustre on the edges, with crystalline facets within. The highly converted steel is used for tools that require to be made very hard; the slightly converted, for softer and more elastic articles, such as springs and sword blades.

STEREOTYPE PRINTING, signifies printing by fixed types, or by a cast typographic plate. This plate is made as follows:--The form, composed in ordinary types, and containing one, two, three, or more pages, inversely as the size of the book, being laid flat upon a slab, with the letters looking upwards, the faces of the types are brushed over with oil, or preferably, with plumbago (black lead). A heavy brass rectangular frame of three sides, with bevelled borders, adapted exactly to the size of the pages, is then laid down upon the chase,[61] to circumscribe three sides of its typography; but the fourth side, which is one end of the rectangle, is formed by placing near the types, and over the hollows of the chase, a single brass bar, having the same inwards sloping bevel as the other three sides. The complete frame resembles that of a picture, and serves to define the area and thickness of the cast, which is made by pouring the pap of Paris plaster into its interior space, up to a given line on its edges. The plaster mould, which soon sets, or becomes concrete, is lifted gently off the types, and immediately placed upright on its edge in one of the cells of a sheet-iron rack mounted within the cast-iron oven. An able workman will mould ten sheets octavo in a day, or 160 pages. The moulds are here exposed to air heated to fully 400° F., and become perfectly dry in the course of two hours. As they are now friable and porous, they require to be delicately handled. Each mould, containing generally two pages octavo, is laid, with the impression downwards, upon a flat cast-iron plate, called the floating-plate; this plate being itself laid on the bottom of the dipping-pan, which is a cast-iron square tray, with its upright edges sloping outwards. A cast-iron lid is applied to the dipping-pan, and secured in its place by a screw. The pan having been heated to 400° in a cell of the oven, under the mould-rack, previous to receiving the hot mould, is ready to be plunged into the bath of melted alloy contained in an iron pot placed over a furnace, and it is dipped with a slight deviation from the horizontal plane, in order to facilitate the escape of the air. As there is a minute space between the back or top surface of the mould and the lid of the dipping-pan, the liquid metal, on entering into the pan through the orifices in its corners, floats up the plaster along with the iron plate on which it had been laid, thence called the floating-plate, whereby it flows freely into every line of the mould, through notches cut in its edge, and forms a layer or lamina upon its face, of a thickness corresponding to the depth of the border. Only a thin metal film is left upon the back of the mould. The dipping-pan is suspended, plunged, and removed by means of a powerful crane, susceptible of vertical and horizontal motions in all directions. When lifted out of the bath, it is set in a water-cistern, upon bearers so placed as to allow its bottom only to touch the surface. Thus the metal first concretes below, while, by remaining fluid above, it continues to impart hydrostatic pressure during the shrinkage attendant upon refrigeration. As it thus progressively contracts in volume, more melted metal is fed into the corners of the pan by a ladle, in order to keep up the hydrostatic pressure upon the mould, and to secure a perfect impression, as well as a solid cast. Were the pan more slowly and equably cooled, by being left in the air, the thin film of metal upon the back of the inverted plaster cake would be apt to solidify first, and intercept the hydrostatic action indispensable to the purpose of filling all the lines in its face. A skilful workman makes five dips, containing two pages octavo each, in the course of an hour, or about nine and a half octavo sheets per day. The pan being taken asunder, the compound cake of mould and metal is removed, and beat upon its edges with a wooden mallet, to detach the superfluous metal. The stereotype plate is then handed over to the picker, who planes its edges truly square, turns its back flat upon a lathe to a determinate thickness, and carefully removes the little imperfections occasioned by dirt or air left among the letters when the mould was cast. Should any of them be damaged in the course of the operation, they must be cut out, and replaced by soldering in separate types of the same size and form.

[61] Chase (_chassis_, frame, Fr.), quoin (_coin_, wedge, Fr.), are terms which show that the art of printing came directly from France to England.

STILL (_Alambic_, Fr.; _Blase_, Germ.); is a chemical apparatus, for vaporizing liquids by heat in one part, called the _cucurbit_, and condensing the vapours into liquids in another part, called the _refrigeratory_; the general purpose of both combined being to separate the more volatile fluid particles from the less volatile. In its simplest form, it consists of a retort and a receiver, or of a pear-shaped matrass and a capital, furnished with a slanting tube for conducting away the condensed vapours in drops; whence the term _still_, from the Latin verb _stillare_, to drop. Its chief employment in this country being to eliminate alcohol, of greater or less strength, from fermented wash, I shall devote this article to a description of the stills best adapted to the manufacture of British spirits, referring to chemical authors[62] for those fitted for peculiar objects.

[62] The treatises of Le Normand and Dubrunfaut may also be consulted. The French stills are in general so much complicated with a great many small pipes and passages, as to be unfit for distilling the glutinous wash of grains.

In respect of rapidity and extent of work, stills had attained to an extraordinary pitch of perfection in Scotland about thirty years ago, when legislative wisdom thought fit to levy the spirits duty, per annum, from each distiller, according to the capacity of his still. It having been shown, in a report presented to the House of Commons in 1799, that an 80-gallon still could be worked off in eight minutes, this fact was made the basis of a new fiscal law, on the supposition that the maximum of velocity had been reached. But, instigated by the hopes of enormous gains at the expense of the revenue, the distillers soon contrived to do the same thing in three minutes, by means of broad-bottomed shallow stills, with stirring-chains, and lofty capitals. In the year 1815, that preposterous law, which encouraged fraud and deteriorated the manufacture, was repealed. The whiskey duties having been since levied, independently of the capacity of the still, upon the quantity produced, such rapid operations have been abandoned, and processes of economy in fuel, and purity in product, have been sought after.

One of the greatest improvements in modern distilleries, is completing the analysis of crude spirit at one operation. Chemists had been long familiar with the contrivance of Woulfe, for impregnating with gaseous matter, water contained in a range of bottles; but they had not thought of applying that plan to distillation, when Edouard Adam, an illiterate workman of Montpellier, after hearing accidentally a chemical lecture upon that apparatus, bethought himself of converting it into a still. He caused the boiling-hot vapours to chase the spirits successively out of one bottle into another, so as to obtain in the successive vessels alcohol of any desired strength and purity, “_at one and the same heat_.” He obtained a patent for this invention in 1801, and was soon afterwards enabled, by his success on the small scale, to set up in his native city a magnificent distillery, which excited the admiration of all the practical chemists of that day. In November, 1805, he obtained a certificate of certain improvements for extracting from wine, at one process, the whole of its alcohol. Adam was so overjoyed, after making his first experiments, that he ran about the streets of Montpellier, telling every body of the surprising results of his invention. Several competitors soon entered the lists with him, especially Solimani, professor of chemistry in that city, and Isaac Berard, distiller in the department of Gard; who, having contrived other forms of continuous stills, divided the profits with the first inventor.

The principles of spirituous distillation may be stated as follows:--The boiling point of alcohol varies with its density or strength, in conformity with the numbers in the following table:--

+--------+-------------------+ |Specific| Boiling point, by | |gravity.|Fahrenheit’s scale.| +--------+-------------------+ | 0·7939 | 168·5° | | 0·8034 | 168·0 | | 0·8118 | 168·5 | | 0·8194 | 169·0 | | 0·8265 | 172·5 | | 0·8332 | 173·5 | | 0·8397 | 175·0 | | 0·8458 | 177·0 | | 0·8518 | 179·0 | | 0·8875 | 181·0 | | 0·8631 | 183·0 | | 0·8765 | 187·0 | | 0·8892 | 190·0 | | 0·9013 | 194·0 | | 0·9126 | 197·0 | | 0·9234 | 199·0 | | 0·9335 | 201·0 | +--------+-------------------+

See also the table under ALCOHOL, page 16.

Hence, the lower the temperature of the spirituous vapour which enters the refrigeratory apparatus, the stronger and purer will the condensed spirit be; because the offensive oils, which are present in the wash or wine, are less volatile than alcohol, and are brought over chiefly with the aqueous vapour. A perfect still should, therefore, consist of three distinct members; first, the cucurbit, or kettle; second, the rectifier, for intercepting more or less of the watery and oily particles; and third, the refrigerator, or condenser of the alcoholic vapours.

These principles are illustrated in the construction of the still represented in _figs._ 1057, 1058, 1059, 1060, 1061.; in which the resources of the most refined French stills are combined with a simplicity and solidity suited to the grain distilleries of the United Kingdom. Three principal objects are obtained by the arrangement here shown; first, the extraction from fermented wort or wine, at one operation, of a spirit of any desired cleanness and strength; second, great economy of time, labour, and fuel; third, freedom from all danger of blowing up or boiling over, by mismanaged firing. When a combination of water, alcohol, and essential oil, in the state of vapour, is passed upwards through a series of winding passages, maintained at a determinate degree of heat, between 170° and 180°, the alcohol alone, in any notable proportion, will retain the elastic form, and will proceed onwards into the refrigeratory tube, in which the said passages terminate; while the water and the oil will be in a great measure condensed, arrested, and thrown back into the body of the still, to be discharged with the effete residuum.

The system of passages or channels, represented in _fig._ 1058., is so contrived as to bring the mingled vapours which rise from the alembic _a_, into ample and intimate contact with metallic surfaces, maintained, in a water-bath, at a temperature self-regulated by a heat-governor. See THERMOSTAT.

The neck of the alembic tapers upwards, as shown at _b_, _fig._ 1057.; and at _c_, _fig._ 1058., it enters the bottom, or ingress vestibule, of the rectifier _c_, _f_. _f_ is its top or egress vestibule, which communicates with the bottom one by parallel cases or rectangular channels _d_, _d_, _d_, of which the width is small, compared with the length and height. These cases are open at top and bottom, where they are soldered or riveted into a general frame within the cavity, enclosed by the two covers _f_, _c_, which are secured round their edges _e_, _e_, _e_, _e_, with bolts and packing. Each case is occupied with a numerous series of shelves or trays, placed at small distances over each other, in a horizontal or slightly inclined position, of which a side view is given in _fig._ 1059., and cross sections at _d_, _d_, _d_, _fig._ 1058. Each shelf is turned up a little at the two edges, and at one end, but sloped down at the other end, that the liquor admitted at the top may be made to flow slowly backwards and forwards in its descent through the system of shelves or trays, as indicated by the darts and spouts in _fig._ 1059. The shelves of each case are framed together by two or more vertical metallic rods, which pass down through them, and are fixed to each shelf by solder, or by screw-nuts. By this means, if the cover _f_, be removed, the sets of shelves may be readily lifted out of the cases and cleaned; for which reason they are called _movable_.

The intervals _i_, _i_, _i_, _fig._ 1058., between the cases, are left for the free circulation of the water contained in the bath-vessel _g_, _g_; these intervals being considerably narrower than the cases.

_Fig._ 1060. represents in plan the surface of the rectifying cistern, shown in two different sections in _figs._ 1058. and 1059. _h_, _k_, _figs._ 1058. and 1060., is the heat-governor, shaped somewhat like a pair of tongs. Each leg is a compound bar, consisting of a flat bar or ruler of steel, and one of brass alloy, riveted facewise together, having their edges up and down. The links, at _k_, are joined to the free ends of these compound bars, which, receding by increase and approaching by decrease of temperature, act by a lever on the stopcock _l_, fixed to the pipe of a cold-water back, and are so adjusted by a screw-nut, that whenever the water in the bath vessel _g_, _g_, rises above the desired temperature, cold water will be admitted, through the stopcock _l_, and pipe _n_, into the bottom of the cistern, and will displace the over-heated water by the overflow-pipe _m_. Thus a perfect equilibrium of caloric may be maintained, and alcoholic vapour of correspondent uniformity transmitted to the refrigeratory.

_Fig._ 1061. is the cold condenser, of similar construction to the rectifier, _fig._ 1058.; only the water cells should be here larger in proportion to the vapour channels _d_, _d_. This refrigeratory system will be found very powerful, and it presents the great advantage of permitting its interior to be readily inspected and cleansed. It is best made of laminated tin, hardened with a little copper alloy.

The mode of working the preceding apparatus will be understood by the following instructions. Into the alembic, _a_, let as much fermented liquor be admitted as will protect its bottom from being injured by the fire, reserving the main body in the charging-back. Whenever the ebullition in the alembic has raised the temperature of the water-bath _g_, _g_, to the desired pitch, whether that be 170°, 175°, or 180°, the thermostatic instrument is to be adjusted by its screw-nut, and then the communication with the charging-back is to be opened by moving the index of the stopcock o, over a proper portion of its quadrantal arch. The wash will now descend in a slender equable stream, through the pipe _o_, _f_, thence spread into the horizontal tube _p_, _p_, and issue from the orifices of distribution, as seen in the figure, into the respective flat trays or spouts. The manner of its progress is seen for one set of trays, in _fig._ 1059. The direction of the stream in each shelf is evidently the reverse of that in the shelf above and below it; the turned-up end of one shelf corresponding to the discharge slope of its neighbour.

By diffusing the cool wash or wine in a thin film over such an ample range of surfaces, the constant tendency of the bath to exceed the proper limit of temperature is counteracted to the utmost, without waste of time or fuel; for the wash itself, _in transitu_, becomes boiling-hot, and experiences a powerful steam distillation. By this arrangement a very moderate influx of cold water, through the thermostatic stopcock, suffices to temper the bath; such an extensive vaporization of the wash producing a far more powerful refrigerant influence than its simple heating to ebullition. It deserves to be remarked, that the maximum distillatory effect, or the bringing over the greatest quantity of pure spirits in the least time, and with the least labour and fuel, is here accomplished without the least steam pressure in the alembic; for the passages are all pervious to the vapour; whereas, in almost every wash-still heretofore contrived for similar purposes, the spirituous vapours must force their way through successive layers of liquid, the total pressure produced by which causes undue elevation of temperature, and obstruction to the process. Whatever supplementary refrigeration of the vapours in their passage through the bath may be deemed proper, will be administered by the thermostatic regulator.

Towards the end of the process, after all the wash has entered the alembic, it may be sometimes desirable, for the sake of despatch, to modify the thermostat, by its adjusting-screw, so that the bath may take a higher temperature, and allow the residuary feints to run rapidly over, into a separate cistern. This weak fluid may be pumped back into the alembic, as the preliminary charge of a fresh operation.

The above plan of a water-bath regulated by the thermostat, may be used simply as a rectifying cistern, without transmitting the spirit or wash down through it. The series of shelves will cause the vapours from the still to impinge against a most extensive system of metallic surfaces, maintained at a steady temperature, whereby their watery and crude constituents will be condensed and thrown back, while their fine alcoholic particles will proceed forwards to the refrigeratory. Any ordinary still may be readily converted into this self-rectifying form, by merely interposing the cistern, _fig._ 1058., between the alembic and the worm-tub. The leading novelty of the present invention is the _movable_ system of shelves or trays, enclosed in metallic cases, separated by water, combined with the thermostatic regulator. By this combination, any quality of spirits may be procured at one step from wash or wine, by an apparatus, simple, strong and easily kept in order.

The empyreumatic taint which spirits are apt to contract from the action of the naked fire on the bottom of the still, may be entirely prevented by the use of a bath of potash lye, _p_, _p_, _fig._ 1057.; for thus a safe and effectual range of temperature, of 300° F., may be conveniently obtained. The still may also be used without the bath vessel.

Mr. D. T. Shears, of Southwark, obtained a patent in March, 1830, for certain improvements and additions to stills, which are ingenious. They are founded upon a previous patent, granted to Joseph Corty, in 1818; a section of whose contrivance is shown in _fig._ 1062., consisting of a first still _a_, a second still _b_, a connecting tube _c_, from the one end to the other, and the tube _d_, which leads from the second still-head down through the bent tube _e_, _e_, to the lower part of the condensing apparatus.

The original improvements described under Corty’s patent, consisted further, in placing boxes _f_, _f_, _f_, of the condensing apparatus in horizontal positions, and at a distance from each other, in order that the vapour might ascend through them, for the purpose of discharging the spirit by the top tube _g_, and pipe _h_, into the worm, in a highly rectified or concentrated state. In each of the boxes _f_, there is a convex plate or inverted dish _i_, _i_, _i_, and the vapour in rising from the tube _e_, strikes against the concave or under part of the first dish, and then escapes round its edges, and over its convex surface, to the under part of the second dish, and so on to the top, the condensed part of the vapour flowing down again into the still, and the spirit passing off by the pipe _h_, at top; and as the process of condensation will be assisted by cooling the vapour as it rises, cold water is made to flow over the tops of the boxes _f_, from a cock _k_, and through small channels or tubes on the sides of the boxes, and is ultimately discharged by the pipe _l_, at bottom.

_Fig._ 1063. represents a peculiarly shaped tube _a_, through which the spirit is described as passing after leaving the end of the worm at _b_, which tube is open to the atmospheric air at _z_; _c_, is the passage through which the carbonic acid gas is described as escaping into the vessel of water _d_.

Now the improvements claimed under the present patent, are exhibited in _figs._ 1064, 1065, and 1066. _Fig._ 1064. represents the external appearance of a still, the head of which is made very capacious, to guard against over-boiling by any mismanagement of the fire; _fig._ 1065. is the same, partly in section. On the top of the still-head is formed the first-described rectifying apparatus, or series of condensing boxes. The vapour from the body of the still filling the head, meets with the first check from the dish or lower vessel _i_, and after passing under its edges, ascends and strikes against the lower part of the second dish or vessel _i_, and so on, till it ultimately leaves the still-head by the pipe at top.

This part of the apparatus is slightly altered from the former, by the substitution of hollow convex vessels, instead of the inverted dishes before described, which vessels have rims descending from their under surfaces, for the purpose of retaining the vapour. The cold water, which, as above described, flowed over the tops of the boxes _f_, for the purpose of cooling them, now flows also through the hollow convex vessels _i_, within the boxes, and by that means greatly assists the refrigerating process, by which the aqueous parts of the vapour are more readily condensed, and made to fall down and flow back again into the body of the still, while the spirituous parts pass off at top to the worm, in a very high state of rectification.

After the water employed for the refrigeration has passed over all the boxes, and through all the vessels, it is carried off by the pipe _m_, through the vessel _n_, called the wash-heater; that is, the vessel in which the wash is placed previous to introducing it into the still. The pipe _m_, is coiled round in the lower part of the vessel _n_, in order that the heated water may communicate its caloric to the wash, instead of losing the heat by allowing the water to flow away. After the heated water has made several turns round the wash heater, it passes out at the curved pipe _o_, which is bent up, in order to keep the coils of the pipe within always full of water.

Instead of the coiled pipe _n_, last described, the patentee proposes sometimes to pass the hot water into a chamber in a tub or wooden vessel, as at _n_, in _fig._ 1061., in which the wash to be heated occupies the upper part of the vessel, and is separated from the lower part by a thin metallic partition.

The swan-neck _h_, _figs._ 1064. and 1065., which leads from the head of the still, conducts the spirit from the still through the wash-heater, where it becomes partially cooled, and gives out its heat to the wash; and from thence the spirit passes to the worm tub, and being finally condensed, is passed through a safety tube, as (_fig._ 1058.) before described, and by the funnel is conducted into the cask below.

Should any spirit rise in the wash-heater during the above operation, it will be carried down to the worm by the neck _p_, and coiled pipe, and discharged at its lower end; or it may be passed into the still-head, as shown in _fig._ 1062.

A patent was obtained by Mr. Æneas Coffey, in August, 1830, for a still, which has been since mounted in several distilleries. It is economical in fuel, labour, and time, but is said not to produce a clean spirit, without peculiar attention.

The apparatus is represented in _fig._ 1067. _a_, _b_, _c_, _d_, is a sectional view of that part of the still wherein the wash is deprived of its alcohol, and the vapours analyzed. It is described as consisting of a chamber or vessel _a_, with the vertical chamber _b_, _c_, placed above it; the lower half of this chamber is divided into compartments by horizontal plates _e_, _e_, _e_, of thin copper or other metal; each of these plates is turned down at one side, until it nearly touches the plate next underneath it, as shown in the figure; thus leaving a passage throughout the whole of them, by which any liquid falling on the top plate may descend into the next under it, and from that to the third, and so on, from plate to plate, at the alternate ends, until it arrives at the last plate, wherein it falls into the vessel _a_, by the pipe _f_; each of these plates is furnished with several light valves, opening upwards, through which any steam or vapour may ascend; it may also be perforated with holes, but they must not be so numerous or so large as to allow of all the steam passing through them without raising the valves; _c_, is a pipe by which the alcoholic vapour, after it has been analyzed, and has acquired the proper strength, is conducted into the vessel _d_, which is made perfectly close; the vapour will here be condensed on the surface of the pipe _g_, _g_, _g_; from this chamber it will descend in a liquid state into the pipe _h_, whence it may be conducted to a worm or refrigerator, to be cooled in the ordinary way; _i_, is a vessel through which the spent wash flows, after being operated upon in the distilling apparatus, and is discharged in a state of ebullition; _j_, is a vessel or chamber containing the wash to be distilled. A force pump may be substituted, to force the wash through the pipes _k_, and distilling apparatus, with the velocity required.

The patentee states that it is requisite the wash should be passed through the pipe _k_, with sufficient velocity and force, so as to prevent the deposition of sediment in the pipe; the wash in its passage through the pipe _k_, will gradually become increased in temperature as it passes through the spent wash in the chamber, and the close vessel _d_, until it is discharged nearly at the boiling point on the upper plate in the chamber, where it comes in contact with the vapours arising from the vessel _a_.

It is to be observed, that the wort does not reach the boiling point while in the pipe _k_, _k_; to ascertain which, a thermometer is placed on the pipe, and by increasing or diminishing the quantity of wash, its temperature may be regulated. The wash, after being discharged from the pipe _k_, descends from plate to plate as before mentioned, at which time a supply of steam from a boiler, or generator is admitted into the apparatus, through the pipe.

The lower part of this pipe in the vessel _a_, is pierced with a number of small holes, so as to spread the steam over the vessel; it then rises upwards, passing through the plate by the small holes and valves, and through the stratum or sheet of wash flowing over them; the wash, as it descends, gives out a portion of its alcohol to the steam, as it passes over every plate, until it is entirely deprived of its spirit, which it will generally do by the time it arrives at the 7th or 8th plate; but it is better to employ a greater number, to guard against accidents or neglect.

A small steam pipe rises from the chamber _a_, with its upper end opening into the box or chamber; into this chamber the end of a worm projects from the cistern of cold water; the steam rising up the pipe is nearly all condensed in the worm, and flows back into the chamber _a_, by the pipe. The small portion of the steam uncondensed, is allowed to escape at the upper end of the worm, and the flame of a small lamp or taper is to be constantly kept over the orifice; when, should the least quantity of alcohol descend with the wash into the chamber _a_, it will rise with the steam through the pipe and worm, and immediately take fire from the flame of the lamp or taper, thereby warning the attendant to increase the supply of steam or diminish the quantity of wash, as may seem necessary.

I shall conclude this article with a description of the cheap still which is commonly employed by the chemists in Berlin for rectifying alcohol. _a_, is the ash-pit; _b_, the fireplace; _c_, _c_, the flues, which go spirally round the sides of the cucurbit _d_; _e_, the capital, made of block tin, and furnished with a brass edge, which fits tight to a corresponding edge on the mouth of _d_; _f_, _f_, the slanting pipes of the capital; _g_, the oval refrigeratory, made of copper; _h_, the water-gauge glass tube; _i_, a stopcock for emptying the vessel; _k_, do., for drawing off the hot water from the surface; _l_, tube for the supply of cold water. A double cylinder of tin is placed in the refrigeratory, of which the outer one _m_, _m_, stands upon three feet, and is furnished with a discharge pipe _n_. The inner one _o_, _o_, which is open above, receives cold water through the pipe _p_, and lets the warm water flow off through the short tube _q_, into the refrigeratory. In the narrow space between the two cylinders, the vapours proceeding from the capital are condensed, and pass off in the liquid state through _n_. The refrigeratory is made oval, in order to receive two condensers alongside of each other in the line of the longer axis; though only one, and that in the middle, is represented in the figure.

STOCKING MANUFACTURE. See HOSIERY.

STONE, is earthy matter, condensed into so hard a state as to yield only to the blows of a hammer, and therefore well adapted to the purposes of building. Such was the care of the antients to provide strong and durable materials for their public edifices, that but for the desolating hands of modern barbarians, in peace and in war, most of the temples and other public monuments of Greece and of Rome would have remained perfect at the present day, uninjured by the elements during 2000 years. The contrast, in this respect, of the works of modern architects, especially in Great Britain, is very humiliating to those who boast so loudly of social advancement; for there is scarcely a public building of recent date, which will be in existence one thousand years hence. Many of the most splendid works of modern architecture are hastening to decay, in what may be justly called the very infancy of their existence, if compared with the date of those erected in antient Italy, Greece, and Egypt. This is remarkably the case with the three bridges of London, Westminster, and Blackfriars; the foundations of which began to perish most visibly in the very lifetime of their constructors. Every stone intended for a durable edifice, ought to be tested as to its durability, by immersion in a saturated solution of sulphate of soda, and exposure during some days to the air. The crystallization which ensues in its interior, will cause the same disintegration of its substance which frost would occasion in a series of years.

STONE, ARTIFICIAL, for statuary and other decorations of architecture, has been made for several years with singular success at Berlin, by Mr. Feilner. His materials are nearly the same with those of English pottery; and the plastic mass is fashioned either in moulds, or by hand. His kilns, which are peculiar in form, and economical in fuel, deserve to be generally known. _Figs._ 1069. and 1070. represent his round kiln; _fig._ 1069. being an oblique section in the line A, B, C, of _fig._ 1070., which is a ground plan in the line D, _a_, _b_, E, of _fig._ 1069. The inner circular space _c_, covered with the elliptical arch, is filled with the figures to be baked, set upon brick supports. The hearth is a few feet above the ground; and there are steps before the door _d_, for the workmen to mount by, in charging the kiln. The fire is applied on the four sides under the hearth. The flame of each passes along the straight flues _f i_, _f i_, and _f k_. In the second annular flue _g_, _g_, as also in the third _l_, _l_, the flame of each fire is kept apart, being separated from the adjoining, by the stones _h_ and _m_. In the fourth flue _n_, the flames again come together, as also in _o_, and ascend by the middle opening. Besides this large orifice, there are several small holes, _p_, _p_, in the hearth over the above flues, to lead the flames from the other points into contact with the various articles. There are also channels _q_, _q_, in the sides, enclosed by thin walls _r_, to promote the equable distribution of the heat; and these are placed right over the first fire-flues _e_. The partitions _r_, are perforated with many holes, through which, as well as from their tops, the flame may be directed inwards and downwards; _s_ are the vents for carrying off the flames into the upper space _u_, which is usually left empty. These vents can be closed by iron damper-plates, pushed in through the side-slits of the dome. _t_, _t_, are peep-holes, for observing the state of ignition in the furnace; but they are most commonly bricked up. _Fig._ 1071. is a vertical section, and _fig._ 1072. a plan, of an excellent kiln for baking clay to a stony consistence, for the above purpose, or for burning fire-bricks. A, is the lower; B, the middle; C, the upper kiln; and D, the hood, terminating in the chimney E. _a_, _a_, is the ash-pit; _b_, _b_, the vault for raking out the ashes; it is covered with an iron door _c_. _d_, is the peep-hole, filled with a clay stopper; _e_, is the fireplace; _f_, _f_, a vent in the middle of each arch; _g_, _g_, flues at the sides of the arches, situated between the two fireplaces; _h_, _i_, _k_, are apertures for introducing the articles to be baked; _l_, a grate for the fire in the uppermost kiln; _m_, the ash-pit; _n_, the fire-door; _o_, openings through which the flames of a second fire are thrown in. At first, only the ground kiln A, is fired, with cleft billets of pine-wood, introduced at the opening _e_; when this is finished, the second is fired; and then the third, in like manner. This kiln is very like the porcelain kiln of Sèvres, and is employed in many places for baking stoneware.

Mr. Keene obtained a patent, about a year ago, for making a factitious stone-paste in the following way:--He dissolves one pound of alum in a gallon of water, and in this solution he soaks 84 pounds of gypsum calcined in small lumps. He exposes these lumps in the open air for about eight days, till they become apparently dry, and then calcines them in an oven at a dull-red heat. The waste heat of a coke oven is well adapted for this purpose. (See PITCOAL, COKING OF.) These lumps, being ground and sifted, afford a fine powder, which, when made up into a paste with the proper quantity of water, forms the petrifying ground. The mass soon concretes, and after being brushed over with a thin layer of the petrifying paste, may be polished with pumice, &c., in the usual way. It then affords a body of great compactness and durability. If half a pound of copperas be added to the solution of the alum, the gypsum paste, treated as above, has a fine cream or yellow colour. This stone stands the weather well.

STONEWARE. (_Fayence_, Fr.; _Steingut_, Germ.) See POTTERY.

STORAX, STYRAX, flows from the twigs and the trunk of the _Liquidambar styraciflua_, a tree which grows in Louisiana, Virginia, and Mexico. Liquidamber, as this resin is also called, is a brown or ash-gray substance, of the consistence of turpentine, which dries up rapidly, has an agreeable smell, like benzoin, and a bitterish, sharp, burning taste. It dissolves in four parts of alcohol, and affords 1·4 per cent. of benzoic acid.

STOVE (_Poële_, _Calorifère_, Fr.; _Ofen_, Germ.); is a fireplace, more or less close, for warming apartments. When it allows the burning coals to be seen, it is called a stove-grate. Hitherto stoves have rarely been had recourse to in this country for heating our sitting-rooms; the cheerful blaze and ventilation of an open fire being generally preferred. But last winter, by its inclemency, gave birth to a vast multitude of projects for increasing warmth and economizing fuel, many of them eminently insalubrious, by preventing due renewal of the air, and by the introduction of noxious fumes into it. When coke is burned very slowly in an iron box, the carbonic acid gas which is generated, being half as heavy again as the atmospherical air, cannot ascend in the chimney at the temperature of 300° F.; but regurgitates into the apartment through every pore of the stove, and poisons the atmosphere. The large stoneware stoves of France and Germany are free from this vice; because, being fed with fuel from the outside, they cannot produce a reflux of carbonic acid into the apartment, when their draught becomes feeble, as inevitably results from the obscurely burning stoves which have the doors of the fireplace and ash-pit immediately above the hearth-stone.

I have recently performed some careful experiments upon this subject, and find that when the fuel is burning so slowly in the stove as not to heat the iron surface above the 250th or 300th degree of Fahr., there is a constant deflux of carbonic acid gas from the ash-pit into the room. This noxious emanation is most easily evinced by applying the beak of a matrass, containing a little Goulard’s extract (solution of subacetate of lead), to a round hole in the door of the ash-pit of a stove in this languid state of combustion. In a few seconds the liquid will become milky, by the reception of carbonic acid gas. I shall be happy to afford ocular demonstration of this fact to any incredulous votary of the pseudo-economical, anti-ventilation, stoves now so much in vogue. There is no mode in which the health and life of a person can be placed in more insidious jeopardy, than by sitting in a room with its chimney closed up with such a choke-damp-vomiting stove.

That fuel may be consumed by an obscure species of combustion, with the emission of very little heat, was clearly shown in Sir H. Davy’s _Researches on Flame_. “The facts detailed on insensible combustion,” says he, “explain why so much more heat is obtained from fuel when it is burned quickly, than slowly; and they show that, in all cases, the temperature of the acting bodies should be kept as high as possible; not only because the general increment of heat is greater, but likewise because those combinations are prevented, which, at lower temperatures, take place without any considerable production of heat. These facts likewise indicate the source of the great error into which experimenters have fallen, in estimating the heat given out in the combustion of charcoal; and they indicate methods by which the temperature may be increased, and the limits to certain methods.” These conclusions are placed in a strong practical light by the following simple experiments:--I set upon the top orifice of a small cylindrical stove, a hemispherical copper pan, containing six pounds of water, at 60° F., and burned briskly under it 3-1/2 pounds of coke in an hour; at the end of which time, 4-1/2 pounds of water were boiled off. On burning the same weight of coke _slowly_ in the same furnace, surmounted by the same pan, in the course of 12 hours, little more than one-half the quantity of water was exhaled. Yet, in the first case, the aerial products of combustion swept so rapidly over the bottom of the pan, as to communicate to it not more than one-fourth of the effective heat which might have been obtained by one of the plans described in the article EVAPORATION; while, in the second case, these products moved at least 12 times more slowly across the bottom of the pan, and ought therefore to have been so much the more effective in evaporation, had they possessed the same power or quantity of heat.

Stoves, when properly constructed, may be employed both safely and advantageously to heat entrance-halls upon the ground story of a house; but care should be taken not to vitiate the air by passing it over ignited surfaces, as is the case with most of the patent stoves now foisted upon the public. _Fig._ 1073. exhibits a vertical section of a stove which has been recommended for power and economy; but it is highly objectionable, as being apt to scorch the air. The flame of the fire A, circulates round the horizontal pipes of cast iron, _b b_, _c c_, _d d_, _e e_, which receive the external air at the orifice _b_, and conduct it up through the series, till it issues highly heated at K, L, and may be thence conducted wherever it is wanted. The smoke escapes through the chimney B. This stove has evidently two prominent faults; first, it heats the air-pipes very unequally, and the undermost far too much; secondly, the air, by the time it has ascended through the zigzag range to the pipe _e e_, will be nearly of the same temperature with it, and will therefore abstract none of its heat. Thus the upper pipes, if there be several in the range, will be quite inoperative, wasting their warmth upon the sooty air.

_Fig._ 1074. exhibits a transverse vertical section of a far more economical and powerful stove, in which the above evils are avoided. The products of combustion of the fire A, rise up between two brick walls, so as to play upon the bed of tiles B, where, after communicating a moderate heat to the series of slanting pipes whose areas are represented by the small circles _a_, _a_, they turn to the right and left, and circulate round the successive rows of pipes _b b_, _c c_, _d d_, _e e_, and finally escape at the bottom by the flues _g_, _g_, pursuing a somewhat similar path to that of the burned air among a bench of gas-light retorts. It is known, that two-thirds of the fuel have been saved in the gas-works by this distribution of the furnace. For the purpose of heating apartments, the great object is to supply a vast body of genial air; and, therefore, merely such a moderate fire should be kept up in A, as will suffice to warm all the pipes pretty equably to the temperature of 220° Fahr.; and, indeed, as they are laid with a slight slope, are open to the air at their under ends, and terminate at the upper in a common main pipe or tunnel, they can hardly be rendered very hot by any intemperance of firing. I can safely recommend this stove to my readers. If the tubes be made of stoneware, its construction will cost very little; and they may be made of any size, and multiplied so as to carry off the whole effective heat of the fuel, leaving merely so much of it in the burned air, as to waft it fairly up the chimney.

I shall conclude this article by a short extract of a paper which was read before the Royal Society, on the 16th of June, 1836, _upon warming and ventilating apartments_; a subject to which my mind had been particularly turned at that time, by the Directors of the Customs Fund of Life Assurance, on account of the very general state of indisposition and disease prevailing among those of their officers (nearly 100 in number) engaged on duty in the Long Room of the Custom House, London.

“The symptoms of disorder experienced by the several gentlemen (about twenty in number), whom I examined, out of a great many who were indisposed, were of a very uniform character. The following is the result of my researches:--

“A sense of tension or fulness of the head, with occasional flushings of the countenance, throbbing of the temples, and vertigo, followed, not unfrequently, with a confusion of ideas, very disagreeable to officers occupied with important and sometimes intricate calculations. A few are affected with unpleasant perspiration on their sides. The whole of them complain of a remarkable coldness and languor in their extremities, more especially the legs and feet, which has become habitual, denoting languid circulation in these parts, which requires to be counteracted by the application of warm flannels on going to bed. The pulse is, in many instances, more feeble, frequent, sharp, and irritable, than it ought to be, according to the natural constitution of the individuals. The sensations in the head occasionally rise to such a height, notwithstanding the most temperate regimen of life, as to require cupping, and at other times depletory remedies. Costiveness, though not a uniform, is yet a prevailing symptom.

“The sameness of the above ailments, in upwards of one hundred gentlemen, at very various periods of life, and of various temperaments, indicates clearly sameness in the cause.

“The temperature of the air in the Long Room ranged, in the three days of my experimental inquiry, from 62° to 64° of Fahrenheit’s scale; and in the Examiner’s Room it was about 60°, being kept somewhat lower by the occasional shutting of the hot-air valve, which is here placed under the control of the gentlemen; whereas that of the Long Room is designed to be regulated in the sunk story, by the fireman of the stove, who seems sufficiently careful to maintain an equable temperature amidst all the vicissitudes of our winter weather. Upon the 7th of January, the temperature of the open air was 50°; and on the 11th it was only 35°; yet upon both days the thermometer in the Long Room indicated the same heat, of from 62° to 64°.

“The hot air discharged from the two cylindrical stove-tunnels into the Long Room was at 90° upon the 7th, and at 110° upon the 11th. This air is diluted, however, and disguised, by admixture with a column of cold air, before it is allowed to escape. The air, on the contrary, which heats the Examiner’s Room, undergoes no such mollification, and comes forth at once in an ardent blast of fully 170°; not unlike the simoom of the desert, as described by travellers. Had a similar nuisance, on the greater scale, existed in the Long Room, it could not have been endured by the merchants and other visitors on business: but the disguise of an evil is a very different thing from its removal. The direct air of the stove, as it enters the Examiner’s Room, possesses, in an eminent degree, the disagreeable smell and flavour imparted to air by the action of red-hot iron; and, in spite of every attention on the part of the fireman to sweep the stove apparatus from time to time, it carries along with it abundance of burned dusty particles.

“The leading characteristic of the air in these two rooms, is its dryness and disagreeable smell. In the Long Room, upon the 11th, the air indicated, by Daniell’s hygrometer, 70 per cent. of dryness, while the external atmosphere was nearly saturated with moisture. The thermometer connected with the dark bulb of that instrument stood at 30° when dew began to be deposited upon it; while the thermometer in the air stood at 64°. In the court behind the Custom-house, the external air being at 35°, dew was deposited on the dark bulb of the hygrometer by a depression of only 3°; whereas in the Long Room, on the same day, a depression of 34° was required to produce that deposition. Air, in such a dry state, would evaporate 0·44 in. depth of water from a cistern in the course of twenty-four hours; and its influence on the cutaneous exhalents must be proportionably great.

“As cast iron always contains, beside the metal itself, more or less carbon, sulphur, phosphorus, or even arsenic, it is possible that the smell of air passed over it in an incandescent state, may be owing to some of these impregnations; for a quantity of noxious effluvia, inappreciably small, is capable of affecting not only the olfactory nerves, but the pulmonary organs. I endeavoured to test the air as it issued from the valve in the Examiner’s Room, by presenting to it pieces of white paper moistened with a solution of nitrate of silver, and perceived a slight darkening to take place, as if by sulphurous fumes. White paper, moistened with sulphuretted hydrogen water, was not in the least discoloured. The faint impression on the first test paper, may be, probably, ascribed to sulphurous fumes, proceeding from the ignition of the myriads of animal and vegetable matters which constantly float in the atmosphere, as may be seen in the sunbeam admitted into a dark chamber: to this cause, likewise, the offensive smell of air, transmitted over red-hot iron, may in some measure be attributed, as well as to the hydrogen resulting from the decomposition of aqueous vapour, always present in our atmosphere in abundance; especially close to the banks of the Thames, below London Bridge.

“When a column of air sweeps furiously across the burning deserts of Africa and Arabia, constituting the phenomenon called simoom by the natives, the air becomes not only very hot and dry, but highly electrical, as is evinced by lightning and thunder. Dry sands, devoid of vegetation, cannot be conceived to communicate any noxious gas or vapour to the atmosphere, like the malaria of marshes, called miasmata: it is, hence, highly probable that the blast of the simoom owes its deadly malignity, in reference to animal as well as vegetable life, simply to extreme heat, dryness, and electrical disturbance. Similar conditions, though on a smaller scale, exist in what is called the bell, or cockle, apparatus for heating the Long Room and the Examiner’s apartment in the Custom-house. It consists of a series of inverted, hollow, flattened pyramids of cast iron, with an oblong base, rather small in their dimensions, to do their work sufficiently in cold weather, when moderately heated. The inside of the pyramids is exposed to the flames of coke furnaces, which heat them frequently to incandescence, while currents of cold air are directed to their exterior surfaces by numerous sheet-iron channels. The incandescence of these pyramids, or bells, as they are vulgarly called, was proved by pieces of paper taking fire when I laid them on the summits. Again, since air becomes electrical when it is rapidly blown upon the surfaces of certain bodies, it occurred to me that the air which escapes into the Examiner’s Room might be in this predicament. It certainly excites the sensation of a cobweb playing round the head, which is well known to all who are familiar with electrical machines. To determine this point, I presented a condensing gold-leaf electrometer to the said current of hot air, and obtained faint divergence with negative electricity. The electricity must be impaired in its tension, however, in consequence of the air escaping through an iron grating, and striking against the flat iron valves, both of which tend to restore the electric equilibrium. The air blast, moreover, by being diffused round the glass of the condenser apparatus, would somewhat mask the appearances. Were it worth while, an apparatus might be readily constructed for determining this point, without any such sources of fallacy. The influence of an atmosphere charged with electricity in exciting headache and confusion of thought in many persons, is universally known.

“The fetid burned odour of the stove air, and its excessive avidity for moisture, are of themselves, however, sufficient causes of the general indisposition produced among the gentlemen who are permanently exposed to it in the discharge of their public duties.

“From there being nearly a vacuum, as to aqueous vapour, in the said air, while there is nearly a plenum in the external atmosphere round about the Custom-house, the vicissitudes of feeling in those who have occasion to go out and in frequently, must be highly detrimental to health. The permanent action of an artificial desiccated air on the animal economy may be stated as follows:--

“The living body is continually emitting a transpirable matter, the quantity of which, in a grown up man, will depend partly on the activity of the cutaneous exhalents, and partly on the relative dryness or moisture of the circumambient medium. Its average amount, in common circumstances, has been estimated at 20 ounces in twenty-four hours.

“When plunged in a very dry air, the insensible perspiration will be increased; and, as it is a true evaporation or gasefaction, it will generate cold proportionably to its amount. Those parts of the body which are most insulated in the air, and furthest from the heart, such as the extremities, will feel this refrigerating influence most powerfully. Hence the coldness of the hands and feet, so generally felt by the inmates of the apartment, though its temperature be at or above 60°. The brain, being screened by the skull from this evaporating influence, will remain relatively hot, and will get surcharged, besides, with the fluids which are repelled from the extremities by the condensation, or contraction, of the blood-vessels, caused by cold. Hence the affections of the head, such as tension, and its dangerous consequences. If sensible perspiration happen, from debility, to break forth from a system previously relaxed, and plunged into dry air, so attractive of vapour, it will be of the kind called a cold clammy sweat on the sides and back, as experienced by many inmates of the Long Room.

“Such, in my humble apprehension, is a rationale of the phenomena observed at the Custom-house. Similar effects have resulted from hot-air stoves of a similar kind in many other situations.

“After the most mature physical and medical investigation, I am of opinion that the circumstances above specified cannot act permanently upon human beings, without impairing their constitutions, and reducing the value of their lives. The Directors of the Customs Fund are therefore justified in their apprehensions, ‘that the mode of heating the Long Room is injurious to the health of persons employed therein, and that it must unduly shorten the duration of life.’

“It may be admitted, as a general principle, that the comfort of sedentary individuals, occupying large apartments during the winter months, cannot be adequately secured by the mere influx of hot air from separate stove-rooms: it requires the genial influence of radiating surfaces in the apartments themselves, such as of open fires, of pipes, or other vessels filled with hot water or steam. The clothing of our bodies, exposed to such radiation in a pure, fresh, somewhat cool and bracing air, absorbs a much more agreeable warmth than it could acquire by being merely immersed in an atmosphere heated even to 62° Fahr., like that of the Long Room. In the former predicament, the lungs are supplied with a relatively dense air, say at 52° Fahr.; while the external surface of the body or the clothing is maintained at, perhaps, 70° or 75°. This distinctive circumstance has not, I believe, been hitherto duly considered by the stove doctors, each intent on puffing his own pecuniary interest; but it is obviously one of great importance, and which the English people would do well to keep in view; because it is owing to our domestic apartments being heated by open fires, and our factories by steam pipes, that the health of our population, and the expectation of life among all orders in this country, are so much better than in France and Germany, where hot-air stoves, neither agreeable nor inoffensive, and in endless variety of form, are generally employed.

“In conclusion, I take leave to state to you my firm conviction that the only method of warming your Long Room and subsidiary apartments, combining salubrity, safety, and economy, with convenience in erection and durable comfort in use, is by a series of steam pipes laid along the floor, at the line of the desk partitions, in suitable lengths, with small arched junction-pipes rising over the several doorways, to keep the passages clear, and at the same time to allow a free expansion and contraction in the pipes, thereby providing for the permanent soundness of the joints.”

It would not be difficult to construct a stove or stove-grate which should combine economy and comfort of warming an apartment, with briskness of combustion and durability of the fire, without any noxious deflux of carbonic acid. See CHIMNEY.

STRASS; see PASTES.

STRAW-HAT MANUFACTURE. The mode of preparing the Tuscany or Italian straw, is by pulling the bearded wheat while the ear is in a soft milky state, the corn having been sown very close, and of consequence produced in a thin, short, and dwindled condition. The straw, with its ears and roots, is spread out thinly upon the ground in fine hot weather, for three or four days or more, in order to dry the sap; it is then tied up in bundles and stacked, for the purpose of enabling the heat of the mow to drive off any remaining moisture. It is important to keep the ends of the straw air-tight, in order to retain the pith, and prevent its gummy particles from passing off by evaporation.

After the straw has been about a month in the mow, it is removed to a meadow and spread out, that the dew may act upon it, together with the sun and air, and promote the bleaching, it being necessary frequently to turn the straw while this process is going on. The first process of bleaching being complete, the lower joint and root is pulled from the straw, leaving the upper part fit for use, which is then sorted according to qualities; and after being submitted to the action of steam, for the purpose of extracting its colour, and then to a fumigation of sulphur, to complete the bleaching, the straws are in a condition to be platted or woven into hats and bonnets, and are in that state imported into England in bundles, the dried ears of the wheat being still on the straw.

Straw may be easily bleached by a solution of chloride of lime, and also by sulphuring. For the latter purpose, a cask open at both ends, with its seams papered, is to be set upright a few inches from the ground, having a hoop nailed to its inside, about six inches beneath the top, to support another hoop with a net stretched across it, upon which the straw is to be laid in successive handfuls loosely crossing each other. The cask having been covered with a tight overlapping lid, stuffed with lists of cloth, a brazier of burning charcoal is to be inserted within the bottom, and an iron dish containing pieces of brimstone is to be put upon the brazier. The brimstone soon takes fire, and fills the cask with sulphurous acid gas, whereby the straw gets bleached in the course of three or four hours. Care should be taken to prevent such a violent combustion of the sulphur as might cause black burned spots, for these cannot be afterwards removed. The straw, after being aired and softened by spreading it upon the grass for a night, is ready to be split, preparatory to dyeing. Blue is given by a boiling-hot solution of indigo in sulphuric acid, called _Saxon blue_, diluted to the desired shade; yellow, by decoction of turmeric; red, by boiling hanks of coarse scarlet wool in a bath of weak alum water, containing the straw; or directly, by cochineal, salt of tin, and tartar. Brazil wood and archil are also employed for dyeing straw. For the other colours, see their respective titles in this Dictionary.

STRETCHING MACHINE. Cotton goods and other textile fabrics, either white or printed, are prepared for the market by being stretched in a proper machine, which lays all their warp and woof yarns in truly parallel positions. A very ingenious and effective mechanism of this kind was made the subject of a patent by Mr. Samuel Morand, of Manchester, in April, 1834, which serves to extend the width of calico pieces, or of other cloths woven of cotton, wool, silk, or flax, after they have become shrunk in the processes of bleaching, dyeing, &c. I regret that the limits of this volume will not admit of its description. The specification of the patent is published in Newton’s Journal, for December, 1835.

STRONTIA, one of the alkaline earths, of which _strontium_ is the metallic basis, occurs in a crystalline state, as a carbonate, in the lead mines of Strontian in Argyleshire, whence its name. The sulphate is found crystallized near Bristol, and in several other parts of the world; but strontitic minerals are rather rare. The pure earth is prepared exactly like baryta, from either the carbonate or the sulphate. It is a grayish-white powder, infusible in the furnace, of a specific gravity approaching that of baryta, having an acrid, burning taste, but not so corrosive as baryta, though sharper than lime. It becomes hot when moistened, and slakes into a pulverulent hydrate, dissolves in 150 parts of water at 60°, and in much less at the boiling point, forming an alkaline solution called _strontia_ water, which deposits crystals in four-sided tables as it cools. These contain 68 per cent. of water, are soluble in 52 parts of water at 60°, and in about 2 parts of boiling water; when heated they part with 53 parts of water, but retain the other 15 parts, even at a red heat. The dry earth consists of 84·55 of base, and 15·45 of oxygen. It is readily distinguished from baryta, by its inferior solubility, and by its soluble salts giving a red tinge to flame, while those of baryta give a yellow tinge. Fluosilicic acid and iodate of soda precipitate the salts of the latter earth, but not those of the former. The compounds of strontia are not poisonous, like those of baryta. The only preparation of strontia used in the arts is the NITRATE, which see.

STRYCHNIA, is an alkaline base, extracted from the _Strychnos nux vomica_, _Strychnos ignatia_, and the _Upas tiente_; which has been employed in medicine by some of the poison doctors, but is of no use in any of the arts. When introduced into the stomach, strychnia acts with fearful energy, causing lock-jaw immediately, and the death of the animal in a very short time. Half a grain, blown into the throat of a rabbit, proves fatal in five minutes.

STUCCO. See GYPSUM.

SUBERIC ACID, is prepared by digesting grated cork with nitric acid. It forms crystals, which sublime in white vapours when heated.

SUBLIMATE, is any solid matter resulting from condensed vapours, and,

SUBLIMATION, is the process by which the volatile particles are raised by heat, and condensed into a crystalline mass. See CALOMEL and SAL-AMMONIAC, for examples.

SUBSALT, is a salt in which the base is not saturated with acid; as subacetate of lead.

SUCCINIC ACID, _Acid of amber_, (_Acide succinique_, Fr.; _Bernsteinsaüre_, Germ.) is obtained by distilling coarsely pounded amber in a retort by itself, with a heat gradually raised; or mixed with one-twelfth of its weight of sulphuric acid, diluted with half its weight of water. The acid which sublimes is to be dissolved in hot water, to be saturated with potassa or soda, boiled with bone black, to remove the foul empyreumatic oily matter, filtered, and precipitated by nitrate of lead, to convert it into an insoluble succinate; which being washed, is to be decomposed by the equivalent quantity of sulphuric acid. Pure succinic acid forms transparent prisms. The succinate of ammonia is an excellent reagent for detecting and separating iron.

SUGAR (_Sucre_, Fr.; _Zucker_, Germ.); is the sweet constituent of vegetable and animal products. It may be distinguished into two principal species. The first, which occurs in the sugar-cane, the beet-root, and the maple, crystallizes in oblique four-sided prisms, terminated by two-sided summits; it has a sweetening power which may be represented by 100; and in circumpolarization it bends the luminous rays to the right. The second occurs ready formed in ripe grapes and other fruits; it is also produced by treating starch with diastase or sulphuric acid. This species forms cauliflower concretions, but not true crystals; it has a sweetening power which may be represented by 60, and in circumpolarization it bends the rays to the left. Besides these two principal kinds of sugar, some others are distinguished by chemists; as the sugar of milk, of manna, of certain mushrooms, of liquorice-root, and that obtained from sawdust and glue by the action of sulphuric acid; but they have no importance in a manufacturing point of view.

Sugar, extracted either from the cane, the beet, or the maple, is identical in its properties and composition, when refined to the same pitch of purity; only that of the beet seems to surpass the other two in cohesive force, since larger and firmer crystals of it are obtained from a clarified solution of equal density. It contains 5·3 per cent. of combined water, which can be separated only by uniting it with oxide of lead, into what has been called a saccharate; made by mixing syrup with finely ground litharge, and evaporating the mixture to dryness upon a steam-bath. When sugar is exposed to a heat of 400° F., it melts into a brown pasty mass, but still retains its water of composition. Sugar thus fused is no longer capable of crystallization, and is called caramel by the French. It is used for colouring liqueurs. Indeed sugar is so susceptible of change by heat, that if a colourless solution of it be exposed for some time to the temperature of boiling water, it becomes brown and partially uncrystallizable. Acids exercise such an injurious influence upon sugar, that after remaining in contact with it for a little while, though they be rendered thoroughly neutral, a great part of the sugar will refuse to crystallize. Thus, if 3 parts of oxalic or tartaric acid be added to sugar in solution, no crystals of sugar can be obtained by evaporation, even though the acids be neutralized by chalk or carbonate of lime. By boiling cane sugar with dilute sulphuric acid, it is changed into starch sugar. Manufacturers of sugar should be, therefore, particularly watchful against every acidulous taint or impregnation. Nitric acid converts sugar into oxalic and malic acids. Alkaline matter is likewise most detrimental to the grain of sugar; as is always evinced by the large quantity of molasses formed, when an excess of temper lime has been used in clarifying the juice of the cane or the beet. When one piece of lump sugar is rubbed against another in the dark, a phosphorescent light is emitted.

Sugar is soluble in all proportions in water; but it takes four parts of spirits of wine, of spec. grav. 0·830, and 80 of absolute alcohol, to dissolve it, both being at a boiling temperature. As the alcohol cools, it deposits the sugar in small crystals. Caramelized and uncrystallizable sugar dissolves readily in alcohol. Pure sugar is unchangeable in the air, even when dissolved in a good deal of water, if the solution be kept covered and in the dark; but with a very small addition of gluten, the solution soon begins to ferment, whereby the sugar is decomposed into alcohol and carbonic acid, and ultimately into acetic acid.

Sugar forms chemical compounds with the salifiable bases. It dissolves readily in caustic potash lye, whereby it loses its sweet taste, and affords on evaporation a mass which is insoluble in alcohol. When the lye is neutralized by sulphuric acid, the sugar recovers its sweet taste, and may be separated from the sulphate of potash by alcohol, but it will no longer crystallize.

That syrup possesses the property of dissolving the alkaline earths, lime, magnesia, strontites, barytes, was demonstrated long ago by Mr. Ramsay of Glasgow, by experiments published in Nicholson’s Journal, vol. xviii. page 9, for September 1807. He found that syrup is capable of dissolving half as much lime as it contains of sugar; and as much strontites as sugar. Magnesia dissolved in much smaller quantity, and barytes seemed to decompose the sugar entirely. These results have been since confirmed by Professor Daniell. Mr. Ramsay characterized sugar treated with lime as weak, from its sweetening power being impaired; from its solution he obtained, after some time, a deposit of calcareous carbonate. M. Pelouze has lately shown that the carbonic acid in this case is derived from the atmosphere, and is not formed at the expense of the elements of the sugar, as Mr. Daniell had asserted.

Sugar forms with oxide of lead two combinations; the one soluble, the other insoluble. Oxide of lead digested in syrup dissolves to a certain amount, forms a yellowish liquor, which possesses an alkaline reaction, and leaves after evaporation an uncrystallizable, viscid, deliquescent mass. If syrup be boiled with oxide of lead in excess, if the solution be filtered boiling hot, and if the phial be corked in which it is received, white bulky flocks will fall to its bottom in the course of 24 hours. This compound is best dried _in vacuo_. It is in both cases light, tasteless, and insoluble in cold and boiling water; it takes fire like German tinder (AMADOU), when touched at one point with an ignited body, and burns away, leaving small globules of lead. It dissolves in acids, and also in neutral acetate of lead, which forms with the oxide a subsalt, and sets the sugar free. Carbonic acid gas passed through water, in which the above saccharate is diffused, decomposes it with precipitation of carbonate of lead. It consists of 58·26 parts of oxide of lead, and 41·74 sugar, in 100 parts. From the powerful action exercised upon sugar by acids and oxide of lead, we may see the fallacy and danger of using these chemical reagents in sugar-refining. Sugar possesses the remarkable property of dissolving the oxide, as well as the subacetate of copper (verdigris), and of counteracting their poisonous operation. Orfila found that a dose of verdigris, which would kill a dog in an hour or two, might be swallowed with impunity, provided it was mixed with a considerable quantity of sugar. When a solution of sugar is boiled with the acetate of copper, it causes an abundant precipitate of protoxide of copper; when boiled with the nitrates of mercury and silver, or the chloride of gold, it reduces the respective bases to the metallic state.

The following TABLE shows the quantities of Sugar contained in Syrups of the annexed specific gravities.[63] It was the result of experiments carefully made.

[63] The author, in minutes of evidence of Molasses Committee of the House of Commons, 1831, p. 142.

+------------------------+-------------+ |Experimental spec. grav.|Sugar in 100.| | of solution at 60° F. | by weight. | +------------------------+-------------+ | 1·3260 | 66·666 | | 1·2310 | 50·000 | | 1·1777 | 40·000 | | 1·440 | 33·333 | | 1·1340 | 31·250 | | 1·1250 | 29·412 | | 1·1110 | 26·316 | | 1·1045 | 25·000 | | 1·0905 | 21·740 | | 1·0820 | 20·000 | | 1·0685 | 16·666 | | 1·0500 | 12·500 | | 1·0395 | 10·000 | +------------------------+-------------+

If the decimal part of the number denoting the specific gravity of syrup, be multiplied by 26, the product will denote very nearly the quantity of sugar per gallon in pounds weight, at the given specific gravity.[64]

[64] This rule was annexed to an extensive table, representing the quantities of sugar per gallon corresponding to the specific gravities of the syrup, constructed by the author for the Excise, in subserviency to the Beet-root Bill.

Sugar has been analyzed by several chemists; the following TABLE exhibits some of their results:--

+--------+------------+----------+------+-----+-------+ | | Gay Lussac | | | | | | |and Thenard.|Berzelius.|Prout.|Ure. | | +--------+------------+----------+------+-----+-------+ |Oxygen | 56·63 | 49·856 |53·35 |50·33|in 100.| |Carbon | 42·47 | 43·265 |39·99 |43·38| -- | |Hydrogen| 6·90 | 6·875 | 6·66 | 6·29| -- | +--------+------------+----------+------+-----+-------+

_Of the sugar cane, and the extraction of sugar from it._--Humboldt, after the most elaborate historical and botanical researches in the New World, has arrived at the conclusion, that before America was discovered by the Spaniards, the inhabitants of that continent and the adjacent islands were entirely unacquainted with the sugar canes, with any of our corn plants, and with rice. The progressive diffusion of the cane has been thus traced out by the partisans of its oriental origin. From the interior of Asia it was transplanted first into Cyprus, and thence into Sicily, or possibly by the Saracens directly into the latter island, in which a large quantity of sugar was manufactured in the year 1148. Lafitau relates the donation made by William the Second, king of Sicily, to the convent of St. Benoit, of a mill for crushing sugar canes, along with all its privileges, workmen, and dependencies: which remarkable gift bears the date of 1166. According to this author, the sugar cane must have been imported into Europe at the period of the Crusades. The monk Albertus Aquensis, in the description which he has given of the processes employed at Acre and at Tripoli to extract sugar, says, that in the Holy Land, the Christian soldiers being short of provisions, had recourse to sugar canes, which they chewed for subsistence. Towards the year 1420, Dom Henry, regent of Portugal, caused the sugar cane to be imported into Madeira from Sicily. This plant succeeded perfectly in Madeira and the Canaries; and until the discovery of America these islands supplied Europe with the greater portion of the sugar which it consumed.

The cane is said by some to have passed from the Canaries into the Brazils; but by others, from the coast of Angola in Africa, where the Portuguese had a sugar colony. It was transported in 1506, from the Brazils and the Canaries, into Hispaniola or Hayti, where several crushing-mills were constructed in a short time. It would appear, moreover, from the statement of Peter Martyr, in the third book of his first Decade, written during the second expedition of Christopher Columbus, which happened between 1493 and 1495, that even at this date the cultivation of the sugar cane was widely spread in St. Domingo. It may therefore be supposed to have been introduced here by Columbus himself, at his first voyage, along with other productions of Spain and the Canaries, and that its cultivation had come into considerable activity at the period of his second expedition. Towards the middle of the 17th century, the sugar cane was imported into Barbadoes from Brazil, then into the other English West Indian possessions, into the Spanish Islands on the coast of America, into Mexico, Peru, Chile, and, last of all, into the French, Dutch, and Danish colonies.

The sugar cane, _Arundo saccharifera_, is a plant of the graminiferous family, which varies in height from 8 to 10, or even to 20 feet. Its diameter is about an inch and a half; its stem is dense, brittle, and of a green hue, which verges to yellow at the approach of maturity. It is divided by prominent annular joints of a whitish-yellow colour, the plane of which is perpendicular to the axis of the stem. These joints are placed about 3 inches apart; and send forth leaves, which fall off with the ripening of the plant. The leaves are 3 or 4 feet long, flat, straight, pointed, from 1 to 2 inches in breadth, of a sea-green tint, striated in their length, alternate, embracing the stem by their base. They are marked along their edges with almost imperceptible teeth. In the 11th or 12th month of their growth, the canes push forth at their top a sprout 7 or 8 feet in height, nearly half an inch in diameter, smooth, and without joints, to which the name _arrow_ is given. This is terminated by an ample panicle, about 2 feet long, divided into several knotty ramifications, composed of very numerous flowers, of a white colour, apetalous, and furnished with 3 stamens, the anthers of which are a little oblong. The roots of the sugar cane are jointed and nearly cylindrical; in diameter they are about one twelfth of an inch; in their utmost length 1 foot, presenting over their surface a few short radicles.

The stem of the cane in its ripe state is heavy, very smooth, brittle, of a yellowish-violet, or whitish colour, according to the variety. It is filled with a fibrous, spongy, dirty-white pith, which contains very abundant sweet juice. This juice is elaborated separately in each internodary portion, the functions of which are in this respect independent of the portions above and below. The cane may be propagated by seeds or buds with equal facility; but it is usually done by cuttings or joints of proper lengths, from 15 to 20 inches, in proportion to the nearness of the joints, which are generally taken from the tops of the canes, just below the leaves.

There are several varieties of the sugar-cane plant. The first, and longest known, is the creole, or common sugar cane, which was originally introduced at Madeira. It grows freely in every region within the tropics, on a moist soil, even at an elevation of 3000 feet above the level of the sea. In Mexico, among the mountains of Caudina-Masca, it is cultivated to a height of more than 5000 feet. The quantity and quality of sugar which it yields, is proportional to the heat of the place where it grows, provided it be not too moist and marshy.

The second variety of this plant is the Otaheitan cane. It was introduced into the West Indies about the end of the 18th century. This variety, stronger, taller, with longer spaces between the joints, quicker in its growth, and much more productive in sugar, succeeds perfectly well in lands which seem too much impoverished to grow the ordinary cane. It sends forth shoots at temperatures which chill the growth and development of the creole plant. Its maturation does not take more than a year, and is accomplished sometimes in nine months. From the strength of its stem, and the woodiness of its fibres, it better resists the storms. It displays a better inflorescence, weighs a third more, affords a sixth more juice, and a fourth more sugar, than the common variety. Its main advantage, however, is to yield four crops in the same time that the creole cane yields only three. Its juice contains less feculency and mucilage, whence its sugar is more easily crystallized, and of a fairer colour.

Besides these two varieties, another kind is described by Humboldt and Bonpland, under the name of the _violet_ sugar-cane, for its haum and leaves are of this colour. It was transported from Batavia in 1782. It flowers a month sooner than the rest, that is, in August, but it yields less solid sugar, and more liquid, both of which have a violet tint.

In saying that the cane may be propagated by seeds as well as buds, we must remark, that in all the colonies of the New World, the plant flowers, indeed, but it then sends forth a shoot (_arrow_), that is, its stem elongates, and the seed-vessel proves abortive. For this reason, the bud-joints must there be used for its propagation. It grows to seed, however, in India. This circumstance occurs with some other plants, which, when propagated by their roots, cease to yield fertile seeds; such as the banana, the bread-fruit, the lily, and the tulip.

In the proper season for planting, the ground is marked out by a line into rows three or four feet asunder, in which rows the canes are planted about two feet apart. The series of rows is divided into pieces of land 60 or 70 feet broad, leaving spaces of about 20 feet, for the convenience of passage, and for the admission of sun and air between the stems. Canes are usually planted in trenches, about 6 or 8 inches deep, made with the hand-hoe, the raised soil being heaped to one side, for covering-in the young cane; into the holes a negro drops the number of cuttings intended to be inserted, the digging being performed by other negroes. The earth is then drawn about the hillocks with the hoe. This labour has been, however, in many places better and more cheaply performed by the plough; a deep furrow being made, into which the cuttings are regularly planted, and the mould then properly turned in. If the ground is to be afterwards kept clear by the horse-hoe, the rows of canes should be 5 feet asunder, and the hillocks 2-1/2 feet distant, with only one cane left in one hillock. After some shoots appear, the sooner the horse-hoe is used, the more will the plants thrive, by keeping the weeds under, and stirring up the soil. Plant-canes of the first growth have been known to yield, on the brick-mould of Jamaica, in very fine seasons, 2-1/2 tons of sugar per acre. The proper season for planting the cane-slips, containing the buds, namely, the top part of the cane, stripped of its leaves, and the two or three upper joints, is in the interval between August and the beginning of November. Favoured by the autumnal weather, the young plants become luxuriant enough to shade the ground before the dry season sets in; thereby keeping the roots cool and moderately moist. By this arrangement the creole canes are ripe for the mill in the beginning of the second year, so as to enable the manager to finish his crop early in June. There is no greater error in the colonist than planting canes at an improper season of the year, whereby his whole system of operations becomes disturbed and, in a certain degree, abortive.

The withering and fall of a leaf afford a good criterion of the maturity of the cane-joint to which it belonged; so that the eight last leafless joints of two canes, which are cut the same day, have exactly the same age and the same ripeness, though one of the canes be 15 and the other only 10 months old. Those, however, cut towards the end of the dry season, before the rains begin to fall, produce better sugar than those cut in the rainy season, as they are then somewhat diluted with watery juice, and require more evaporation to form sugar. It may be reckoned a fair average product, when one pound of sugar is obtained from one gallon (English) of juice.

_Rattoons_ (a word corrupted from _rejettons_) are the sprouts or suckers that spring from the roots or stoles of the canes that have been previously cut for sugar. They are commonly ripe in 12 months; but canes of the first growth are called plant-canes, being the direct produce of the original cuttings or germs placed in the ground, and require a longer period to bring them to maturity. The first yearly return from the roots that are cut over, are called first rattoons; the second year’s growth, second rattoons; and so on, according to their age. Instead of stocking up his rattoons, holing, and planting the land anew, the planter suffers the stoles to continue in the ground, and contents himself, as the cane-fields become thin and impoverished, with supplying the vacant places with fresh plants. By these means, and with the aid of manure, the produce of sugar per acre, if not apparently equal to that from plant-canes, gives perhaps in the long run as great returns to the owner, considering the relative proportion of the labour and expense attending the different systems. The common yielding on proper land, such as the red soil of Trelawney, in Jamaica, is 7 hogsheads, of 16 cwt. each, to 10 acres of rattoons cut annually; and such a plantation lasts from 6 to 10 years.

When the planted canes are ripe, they are cut close above the ground, by an oblique section, into lengths of 3 or 4 feet, and transported in bundles to the mill-house. If the roots be then cut off, a few inches below the surface of the soil, and covered up with fine mould, they will push forth more prolific offsets or rattoons, than when left projecting in the common way.

OF SUGAR MILLS.

The first machines employed to squeeze the canes, were mills similar to those which serve to crush apples in some cider districts, or somewhat like tan-mills. In the centre of a circular area, of about 7 or 8 feet in diameter, a vertical heavy wheel was made to revolve on its edge, by attaching a horse to a cross beam projecting horizontally from it, and making it move in a circular path. The cane pieces were strewed on the somewhat concave bed in the path of the wheel, and the juice expressed flowed away through a channel or gutter in the lowest part. This machine was tedious and unproductive. It was replaced by the vertical cylinder-mill of Gonzales de Velosa; which has continued till modern times, with little variation of external form, but is now generally superseded by the sugar-mill with horizontal cylinders.

SUGAR-CANE MILL.

_Specification of, and Observations on, the Construction and Use of the best Horizontal Sugar-mill._

_Fig._ 1075. Front elevation of the entire mill. _Fig._ 1076. Horizontal plan. _Fig._ 1077. End elevation. _Fig._ 1078. Diagram, showing the dispositions of the feeding and delivering rollers, feeding board, returner, and delivering board.

_Fig._ 1075. A, A, solid foundation of masonry; B, B, bed plate; C, C, headstocks or standards; D, main shaft (seen only in _fig._ 1076.); E, intermediate shaft; F, F, plummer-blocks of main shaft D, (seen only in _fig._ 1076.); H, driving pinion on the fly-wheel shaft of engine; I, first motion mortise wheel driven by the pinion; K, second motion pinion, on the same shaft; L, second motion mortise-wheel, on the main shaft; M, brays of wood, holding the plummer-blocks for shaft D; N, wrought-iron straps connecting the brays to the standards C, C; O, O, regulating screws for the brays; P, top roller and gudgeons; Q and R, the lower or feeding and delivering rollers; S, clutch for the connexion of the side of lower rollers Q and R, to the main shaft (seen only in _fig._ 1076.); T, T, the drain gutters of the mill-bed (seen only in _fig._ 1076.).

The same letters of reference are placed respectively on the same parts of the mill in each of _figs._ 1075, 1076, and 1077.

The relative disposition of the rollers is shown in the diagram, _fig._ 1078., in which A is the top roller; B, the feeding roller; C, the delivering roller; D, the returner; E, the feed board; F, the delivering board.

The rollers are made two inches and a quarter to two inches and a half thick, and ribbed in the centre. The feeding and delivering rollers have small flanges at their ends (as shown in _fig._ 1075.), between which the top roller is placed; these flanges prevent the pressed canes or begass from working into the mill-bed. The feeding and top rollers are generally fluted, and sometimes diagonally, enabling them the better to seize the canes from the feed-board. It is, however, on the whole, considered better to flute the feeding roller only, leaving the top and delivering rollers plane; when the top roller is fluted, it should be very slightly, for, after the work of a few weeks, its surface becomes sufficiently rough to bite the canes effectively. The practical disadvantage of fluting the delivering rollers, is in the grooves carrying round a portion of liquor, which is speedily absorbed by the spongy begass, as well as in breaking the begass itself, and thus causing great waste.

The feed board is now generally made of cast iron, and is placed at a considerable inclination, to allow the canes to slip the more easily down to the rollers. The returner is also of cast iron, serrated on the edge, to admit the free flowing of the liquor to the mill-bed. The concave returner, formerly used, was pierced with holes to drain off the liquor, but it had the serious disadvantage of the holes choking up with the splinters of the cane, and has therefore been discarded. The delivering board is of cast iron, fitted close to the roller, to detach any begass that may adhere to it, and otherwise mix with the liquor.

In Demerara, Surinam, Cayenne, and the alluvial district of Trinidad, it is usual to attach to the mill a liquor-pump, with two barrels and three adjustments of stroke. This is worked from the gudgeon of the top roller. In action, the liquor from the gutter of the mill-bed runs into the cistern of the pump, and is raised by the pump to the gutter which leads to the clarifier or coppers. Such pumps have brass barrels and copper discharging pipes, are worked with a very slow motion, and require to be carefully adjusted to the quantity of liquor to be raised, which, without such precaution, is either not drawn off sufficiently quick, or is agitated with air in the barrels, and delivered to the gutter in a state of fermentation.

In working this mill, the feeding roller is kept about half an inch distant from the upper roller, but the delivering roller is placed so close to it, as to allow the begass to pass through unbroken.

The practice with this mill is to cut the sugar canes into short lengths of about three feet, and bring them to the mill tied up in small bundles; there the feeder unties them, throws them on the feed board, and spreads them so that they may cross each other as little as possible. They are taken in by the feed rollers, which split and slightly press them; the liquor flows down, and, the returner guiding the canes between the top and delivering rollers, they receive the final pressure, and are turned out on the mill-floor, while the liquor runs back and falls into the mill-bed. The begass, then in the state of _pith_, adhering to the skin of the cane, is tied up in bundles, and after being exposed a short time to the sun, is finally stored in the begass-house for fuel. By an important improvement in this stage of the process, recently introduced, the begass is carried to the begass-house by a carrier chain, worked by the engine.

The relative merits of horizontal and vertical sugar-mills on this construction, may be thus stated:--The horizontal mill is cheaper in construction, and is more easily fixed; the process of feeding is performed at about one-half of the labour, and in a much superior manner; the returner guides the canes to receive the last pressure more perfectly; and the begass is not so much broken as in the vertical mill; but left tolerably entire, so as to be tied, dried, and stored, with less trouble and waste.

The vertical mill has a considerable advantage, in being more easily washed; and it can be readily and cheaply mounted in wooden framing; but the great labour of feeding the vertical mill, renders it nearly inapplicable to any higher power than that of about ten horses. In situations where the moving power is a windmill, or a cattle gin, the vertical mill may be preferred.

The scale of produce of such mills varies according to the climate and soil. In Demerara, a well constructed engine and mill will produce about 100 gallons of liquor per hour for each horse power.

The dimensions of the most approved horizontal mills are these:--

+----------------------+------------------+--------------------+ |Horse-power of Engine.|Length of Rollers.|Diameter of Rollers.| +----------------------+------------------+--------------------+ | | _ft._ _in._ | _inches._ | | 8 | 4 0 | 25 | | 10 | 4 6 | 27 | | 12 | 4 8 | 28 | +----------------------+------------------+--------------------+

The surface speed of the rollers is 3·4 or 3·6 feet per minute; and to provide for the varying resistance arising from irregular feeding, or the accidental crossing of the canes, by which the engine is often _brought up_ so suddenly as to break the fly-wheel shaft, it is necessary to make both the shaft and the fly-wheel of unusual strength and weight.

Sugar is manufactured in the East Indies by two distinct classes of persons; the _ryots_, who raise the sugar cane, extract its juice, and inspissate it to a syrupy consistence; and the _goldars_, who complete the conversion into sugar.

The _ryots_ are the farmers, or actual cultivators of the soil; but, properly speaking, they are merely peasants, toiling under oppressive landlords, and miserably poor. After they cut the canes, they extract the juice by one or other of the rude mills or mortars presently to be described, and boil it down to an entire mass, which is generically called _goor_, without making any attempt to clarify it, or separate the granular sugar from the uncrystallizable molasses. This goor is of various qualities; one of which, in most common use for making sugar, is known amongst the English settlers under the name of _jaggery_. There is a caste in Ceylon, called _jaggeraros_, who make sugar from the produce of the _Caryota urens_, or Kitul tree; and the sugar is styled _jaggery_. Sugar is not usually made in Ceylon from the sugar cane; but either from the juice of the Kitul, from the _Cocos nucifera_, or the _Borassus flabelliformis_ (the Palmyra tree).

Several sorts of cane are cultivated in India.

The _Cadjoolee_ (_fig._ 1079.) is a purple-coloured cane; yields a sweeter and richer juice than the yellow or light coloured, but in less quantities, and is harder to press. It grows in dry lands. When eaten raw, it is somewhat dry and pithy in the mouth, but is esteemed very good for making sugar. It is not known to the West India planter. The leaves rise from a point 6 feet above the ground. An oblique and transverse section of the cane is represented by the parts near the bottom of the figure.

The _Pooree_ is a light-coloured cane, yellow, inclining to white, deeper yellow when ripe and on rich ground. West India planters consider it the same sort as one of theirs. It is softer and more juicy than the preceding, but the juice is less rich, and produces a weaker sugar. It requires seven parts of pooree juice to make as much goor as is produced from six of the cadjoolee. Much of this cane is brought to the Calcutta market, and eaten raw.

The _Cullorah_ thrives in swampy lands, is light-coloured, and grows to a great height. Its juice is more watery, and yields a weaker sugar also than the cadjoolee. However, since much of Bengal consists of low grounds, and since the upland canes are apt to suffer from drought, it deserves encouragement in certain localities.

It is only large farms that cut an acre of cane in a year; one mill, therefore, and one set of the implements used in inspissating the juice, although very rude and simple, serve for several farms, and generally belong to some wealthy man, who lets them out for hire to his poorer neighbours, the whole of whom unite to clear each other’s fields by turns; so that though many people and cattle are employed at one of these miserable sets of works, very few indeed are hired, and the greater part of the labour is performed by the common stock of the farms.

The inspissated juice, or extract of cane, called by the natives _goor_, is of two kinds; one of which may be termed cake extract, and the other pot extract; both being often denominated _jaggery_, as above stated, by the English residents.

One-third of an acre of good land in the southern districts, is reckoned by the farmers to produce 18,891 pounds of cane, and 1,159 pounds of pot extract. Its produce in cake extract is about 952 pounds.

I shall now describe the primitive rude mill and boiler used in preparing the extract of sugar cane, and which are usually let to the ryots by the day. The mill in Dinajpur, _fig._ 1080. is on the principle of a pestle and mortar. The pestle, however, does not beat the canes, but is rubbed against them, as is done in many chemical triturations; and the moving force is two oxen. The mortar is generally a tamarind tree, one end of which is sunk deep in the ground, to give it firmness. The part projecting _a_, _a_, _a_, _a_, may be about two feet high, and a foot and a half in diameter; and in the upper end a hollow is cut, like the small segment of a sphere. In the centre of this, a channel descends a little way perpendicularly, and then obliquely to one side of the mortar, so that the juice, as squeezed from the cane, runs off, by means of a spout _b_, into a strainer _c_, through which it falls into an earthen pot, that stands in a hole _d_, under the spout. The pestle _e_, is a tree about 18 feet in length, and 1 foot in diameter, rounded at its bottom, which rubs against the mortar, and which is secured in its place by a button or knob, that goes into the channel of the mortar. The moving force is applied to a horizontal beam _f_, about 16 feet in length, which turns round about the mortar, and is fastened to it by a bent bamboo _b_. It is suspended from the upper end of the pestle by a bamboo _g_, which has been cut with part of the root, in which is formed a pivot that hangs on the upper point of the pestle. The cattle are yoked to the horizontal beam, at about ten feet from the mortar, move round it in a circle, and are driven by a man, who sits on the beam, to increase the weight of the triturating power. Scarcely any machine more miserable can be conceived; and it would be totally ineffectual, were not the cane cut into thin slices. This is a troublesome part of the operation. The grinder sits on the ground, having before him a bamboo stake, which is driven into the earth, with a deep notch formed in its upper end. He passes the canes gradually through this notch, and at the same time cuts off the slices with a kind of rude chopper.

The _boiling apparatus_ is somewhat better contrived, and is placed under a shed, though the mill is without shelter. The fireplace is a considerable cavity dug in the ground, and covered with an iron boiler _p_, _fig._ 1081. At one side of this, is an opening _q_, for throwing in fuel; and opposite to this, is another opening, which communicates with the horizontal flue. This is formed by two parallel mud walls _r_, _r_, _s_, _s_, about 20 feet long, 2 feet high, and 18 inches distant from each other. A row of eleven earthen boilers _t_, is placed on these walls, and the interstices _u_, are filled with clay, which completes the furnace-flue, an opening _v_, being left at the end, for giving vent to the smoke.

The juice, as it comes from the mill, is first put into the earthen boiler that is most distant from the fire, and is gradually removed from one boiler to another, until it reaches the iron one, where the process is completed. The fireplace is manifestly on the same model as the boiler range in the West Indies, and may possibly have suggested it, since the Hindostan furnace is, no doubt, of immemorial usage. The execution of its parts is very rude and imperfect. The inspissated juice that can be prepared in 24 hours by such a mill, with 16 men and 20 oxen, amounts to no more than 476 lbs.; and it is only in the southern parts of the district, where the people work night and day, that the sugar-works are so productive. In the northern districts, the people work only during the day, and inspissate about one-half the quantity of juice. The average daily make of a West India sugar-house, is from 2 to 3 hogsheads, of 16 cwts each.

The Indian manufacturers of sugar purchase the above inspissated juice or goor from the farmers, and generally prefer that of a granular honey consistence, which is offered for sale in pots. As this, however, cannot conveniently be brought from a distance, some of the cake kind is also employed. The boilers are of two sizes; one adapted for making at each operation about ten cwt.; the other, about eight and a half. The latter is the segment of a sphere, nine feet diameter at the mouth; the former is larger. The boiler is sunk into a cylindrical cavity in the ground, which serves as a fireplace, so that its edge is just above the floor of the boiling-house. The fuel is thrown in by an aperture close to one side of the boiler, and the smoke escapes by a horizontal chimney that passes out on the opposite side of the hut, and has a small round aperture, about ten feet distant from the wall, in order to lessen the danger from fire. Some manufacturers have only one boiler; others as many as four; but each boiler has a separate hut, in one end of which is some spare fuel; and in the other, some bamboo stages, which support cloth strainers, that are used in the operation. This hut is about twenty-four cubits long, and ten broad; has mud walls, six cubits high; and is raised about one cubit above the ground.

For each boiler, two other houses are required: one in which the cane extract is separated by straining from the molasses, is about twenty cubits long by ten wide; another, about thirty cubits long, by eight wide, is that in which, after the extract has been strained, boiled and clarified, the treacle is separated from the sugar by an operation analogous to claying.

Each sugar manufacturer has a warehouse besides, of a size proportional to the number of his boilers.

About 960 pounds of pot extract being divided into four parts, each is put into a bag of coarse sackcloth, hung over an equal number of wide-mouthed earthen vessels, and is besprinkled with a little water. These drain from the bags about 240 lbs. of a substance analogous to West Indian molasses. The remainder in the bags is a kind of coarse muscovado sugar; but is far from being so well drained and freed from molasses as that of the Antilles. The 720 lbs. of this substance are then put into a boiler with 270 pounds of water, and the mixture is boiled briskly for 144 minutes, when 180 additional pounds of water are added, and the boiling is continued for 48 minutes more. An alkaline solution is prepared from the ashes of the plantain tree, strewed over straw placed in the bottom of an earthen pot perforated with holes. Ninety pounds of water are passed through; and 6 pounds of the clear lixivium are added to the boiling syrup, whereby a thick scum is raised, which is removed. After 24 minutes, four and a half pounds of alkaline solution, and about two-fifths of a pound of raw milk, are added; after which the boiling and skimming are continued 24 minutes. This must be repeated from five to seven times, until no more scum appears. 240 pounds of water being now added, the liquor is to be poured into a number of strainers. These are bags of coarse cotton cloth, in the form of inverted quadrangular pyramids, each of which is suspended from a frame of wood, about 2 feet square. The operation of straining occupies about 96 minutes. The strained liquor is divided into three parts: one of these is put into a boiler, with from half a pound to a pound and a half of alkaline solution, one-twelfth of a pound of milk, and 12 pounds of water. After having boiled for between 48 and 72 minutes, three quarters of a pound of milk are added, and the liquor is poured, in equal portions, into four refining pots. These are wide at the mouth, and pointed at the bottom; but are not conical, for the sides are curved. The bottom is perforated, and the stem of a plantain leaf forms a plug for closing the aperture. The two remaining portions of the strained liquor are managed in exactly the same manner; so that each refining pot has its share of each portion. When they have cooled a little, the refining pot is removed to the curing-house, and placed on the ground for 24 hours; next day they are placed on a frame, which supports them at some distance from the ground. A wide-mouthed vessel is placed under each, to receive the viscid liquor that drains from them. In order to draw off this more completely, moist leaves of the _Valisneria spiralis_ are placed over the mouth of the pot, to the thickness of two inches; after 10 or 12 days, these are removed; when a crust of sugar, about half an inch in thickness is found on the surface of the boiled liquor. The crust being broken and removed, fresh leaves are repeatedly added, until the whole sugar has formed; which requires from 75 to 90 days. When cake extract is used, it does not require to be strained before it be put into the boiler.

On the above-described operose and preposterous process, it is needless to make any remarks. While it is adhered to with the tenacity of Hindu habit, the West Indies has no reason to fear the competition of the East, in the manufacture of sugar, provided the former avail themselves of the aids which chemical and mechanical science are ready to supply.

In every part of the Behar and Putna districts, several of the confectioners prepare the coarse article called _shukkur_, which is entirely similar in appearance to the inferior Jamaica sugars. They prepare it by putting some of the thin extract of sugar cane into coarse sackcloth bags, and by laying weights on them, they squeeze out the molasses; a process perfectly analogous to that contemplated in several English patents.

The sugar-mill at Chica Ballapura is worked by a single pair of buffaloes or oxen, _fig._ 1082., going round with the lever A, which is fixed on the top of the right-hand roller. The two rollers have endless screw heads B, which are formed of 4 spiral grooves and 4 spiral ridges, cut in opposite directions, which turn into one another, when the mill is working. These rollers and their heads are of one piece, made of the toughest and hardest wood that can be got, and such as will not impart any bad taste to the juice. They are supported in a thick strong wooden frame, and their distance from each other is regulated by means of wedges, which pass through mortises in the frame planks, and a groove made in a bit of some sort of hard wood, and press upon the axis of one of the rollers. The axis of the other presses against the left-hand side of the hole in the frame-boards. The cane juice runs down the rollers, and through a hole in the lower frame-board, into a wooden conductor, which carries it into an earthen pot. Two long-pointed stakes or piles are driven into the earth, to keep the mill steady, which is all the fixing it requires. The under part of the lowermost plank of the frame rests upon the surface of the ground, which is chosen level and very firm, that the piles may hold the faster. A hole is dug in the earth, immediately below the spout of the conductor, to receive the pot.

The mill used in Burdwan and near Calcutta, is simply two small wooden cylinders, grooved, placed horizontally, close to each other, and turned by two men, one at each end. This simple engine is said completely, but slowly, to express the juice. It is very cheap, the prime cost not being two rupees; and being easily moved from field to field, it saves much labour in the carriage of the cane. Notwithstanding this advantage, so rude a machine must leave a large proportion of the richest juice in the cane-trash.

It is curious to find in the antient arts of Hindostan exact prototypes of the sugar-rollers, horizontal and upright, of relatively modern invention in the New World.

The sugar-mill of Chinapatam, _fig._ 1083., consists of a mortar, lever, pestle, and regulator. The mortar is a tree about 10 feet in length, and 14 inches in diameter: _a_ is a plan of its upper end; _b_ is an outside view; and _c_ is a vertical section. It is sunk perpendicularly into the earth, leaving one end two feet above the surface. The hollow is conical, truncated downwards, and then becomes cylindrical, with a hemispherical projection in its bottom, to allow the juice to run freely to the small opening that conveys it to a spout, from which it falls into an earthen pot. Round the upper mouth of the cone is a circular cavity, which collects any of the juice that may run over from the upper ends of the pieces of cane; and thence a canal conveys this juice, down the outside of the mortar, to the spout. The beam _d_, is about sixteen feet in length, and six inches in thickness, being cut out from a large tree that is divided by a fork into two arms. In the fork an excavation is made for the mortar _b_, round which the beam turns horizontally. The surface of this excavation is secured by a semicircle of strong wood. The end towards the fork is quite open, for changing the beam without trouble. On the undivided end of the beam sits the bullock-driver _e_, whose cattle are yoked by a rope which comes from the end of the beam; and they are prevented from dragging out of the circle by another rope, which passes from the yoke to the forked end of the beam. On the arms _f_, a basket is placed, to hold the cuttings of cane; and between this and the mortar sits the man who feeds the mill. Just as the pestle comes round, he places the pieces of cane sloping down into the cavity of the mortar; and after the pestle has passed, he removes those that have been squeezed.

OF THE MANUFACTURE OF SUGAR IN THE WEST INDIES.

Cane-juice varies exceedingly in richness, with the nature of the soil, the culture, the season, and variety of the plant. It is an opaque fluid, of a dull gray, olive, or olive-green colour; in taste, balmy and saccharine; exhaling the balsamic odour of the cane; slightly viscid; and of a specific gravity varying from 1·033 to 1·106, according to circumstances. When fresh, it consists of two parts; the one liquid, the other solid; the latter of which being merely suspended in the former, and, therefore, separable in a great measure by filtration or repose. The solid matter consists of fragments of the cellular parenchyma of the cane, its fibres, and bark, mechanically protruded through the mill; mixed with a very abundant greenish substance, like that called _chlorophyle_ by chemists.

When left to itself in the colonial climates, the juice runs rapidly into the acetous fermentation; twenty minutes being, in many cases, sufficient to bring on this destructive change. Hence arises the necessity of subjecting it immediately to clarifying processes, speedy in their action. When deprived of its green fecula and glutinous extractive, it is still subject to fermentation; but this is now of the vinous kind. The juice flows from the mill through a wooden gutter lined with lead, and being conducted into the sugar-house, is received in a set of large pans or caldrons, called clarifiers. On estates which make on an average, during crop time, from 15 to 20 hogsheads of sugar a week, three clarifiers, of from 300 to 400 gallons’ capacity each, are sufficient. With pans of this dimension, the liquor may be drawn off at once by a stopcock or syphon, without disturbing the feculencies after they subside. Each clarifier is hung over a separate fire, the flue being furnished with a damper for checking the combustion, or extinguishing it altogether. The clarifiers are sometimes placed at one end, and sometimes in the middle of the house, particularly if it possesses a double set of evaporating pans.

Whenever the stream from the mill cistern has filled the clarifier with fresh juice, the fire is lighted, and the _temper_, or dose of slaked lime, diffused uniformly through a little juice, is added. If an albuminous emulsion be used to promote the clarifying, very little lime will be required; for recent cane-liquor contains no appreciable portion of acid to be saturated. In fact, the lime and alkalies in general, when used in small quantity, seem to coagulate the glutinous extractive matter of the juice, and thus tend to brighten it up. But if an excess of temper be used, the gluten is taken up again by the strong affinity which is known to exist between sugar and lime. Excess of lime may always be corrected by a little alum-water. Where canes grow on a calcareous marly soil, in a favourable season the saccharine matter gets so thoroughly elaborated, and the glutinous mucilage so completely condensed, that a clear juice and a fine sugar may be obtained without the use of lime.

As the liquor grows hot in the clarifier, a scum is thrown up, consisting of the coagulated feculencies of the cane-juice. The fire is now gradually urged till the temperature approaches the boiling point; to which, however, it must not be suffered to rise. It is known to be sufficiently heated, when the scum rises in blisters, which break into white froth; an appearance observable in about forty minutes after kindling the fire. The damper being shut down, the fire dies out; and after an hour’s repose, the clarified liquor is ready to be drawn off into the last and largest in the series of evaporating pans. In the British colonies, these are merely numbered 1, 2, 3, 4, 5, beginning at the smallest, which hangs right over the fire, and is called the _teache_; because in it the trial of the syrup, by _touch_, is made. The flame and smoke proceed in a straight line along a flue to the chimney-stalk at the other end of the furnace. The area of this flue proceeds, with a slight ascent from the fire, to the aperture at the bottom of the chimney; so that between the surface of the grate and the bottom of the teache, there is a distance of 28 inches; while between the bottom of the flue and that of the _grand_, No. 5., at the other end of the range, there are barely 18 inches.

In some sugar-houses there is planted, in the angular space between each boiler, a basin, one foot wide and a few inches deep, for the purpose of receiving the scum which thence flows off into the _grand copper_, along a gutter scooped out on the margin of the brickwork. The skimmings of the _grand_ are thrown into a separate pan, placed at its side. A large cylindrical _cooler_, about 6 feet wide and 2 feet deep, has been placed in certain sugar-works near the teache, for receiving successive charges of its inspissated syrup. Each finished charge is called a skipping, because it is skipped or laded out. The term _striking_ is also applied to the act of emptying the _teache_. When upon one skipping of syrup in a state of incipient granulation in the cooler, a second skipping is poured, this second congeries of saccharine particles agglomerates round the first as _nuclei_ of crystallization, and produces a larger grain; a result improved by each successive skipping. This principle has been long known to the chemist, but does not seem to have been always properly considered or appreciated by the sugar-planter.

From the above described _cooler_, the syrup is transferred into wooden chests or boxes, open at top, and of a rectangular shape; also called _coolers_, but which are more properly crystallizers or granulators. These are commonly six in number; each being about one foot deep, seven feet long, and five or six feet wide. When filled, such a mass is collected, as to favour slow cooling, and consequent large-grained crystallization. If these boxes be too shallow, the grain is exceedingly injured, as may be easily shown by pouring some of the same syrup on a small tray; when, on cooling, the sugar will appear like a muddy soft sand.

The criterion by which the negro boilers judge of the due concentration of the syrup in the teache, is difficult to describe, and depends almost entirely on the sagacity and experience of the individual. Some of them judge by the appearance of the incipient grain on the back of the cooling ladle; but most decide by “_the touch_,” that is, the feel and appearance of a drop of the syrup pressed and then drawn into a thread between the thumb and fore-finger. The thread eventually breaks at a certain limit of extension, shrinking from the thumb to the suspended finger, in lengths somewhat proportional to the inspissation of the syrup. But the appearance of granulation in the thread must also be considered; for a viscid and damaged syrup may give a long enough thread, and yet yield almost no crystalline grains when cooled. Tenacity and granular aspect must therefore be both taken into the account, and will continue to constitute the practical guides to the negro boiler, till a less barbarous mode of concentrating cane-juice be substituted for the present _naked teache_, or _sugar frying-pan_.

That weak sugars are such as contain an inferior proportion of carbon in their composition, was first deduced by me from my experiments on the ultimate analysis of vegetable and animal bodies; an account of which was published in the Philosophical Transactions of the Royal Society for 1822. Since then Dr. Prout has arrived at results comfirmatory of my views. See Philosophical Transactions for 1827. Thus, he found pure sugar-candy, and the best refined sugar, to contain 42·85 parts of carbon per cent.; East India sugar-candy, 41·9 parts; East India raw sugar in a thoroughly dry state, but of a low quality, 40·88; manna sugar, well refined, 28·7; sugar from Narbonne honey, 36·36; sugar from starch, 36·2. Hence, by _caramelizing_ the syrup in the _teache_, not only is the crystallizable sugar blackened, but its faculty of crystallizing impaired, and the granular portion rendered weaker.

A viscous syrup containing much gluten and sugar, altered by lime, requires a higher temperature to enable it to granulate, than a pure saccharine syrup; and therefore the thermometer, though a useful adjuvant, can by no means be regarded as a sure guide, in determining the proper instant for _striking_ the _teache_.

The colonial _curing-house_ is a capacious building, of which the earthen floor is excavated to form the molasses reservoir. This is lined with sheet lead, boards, tarras, or other retentive cement; its bottom slopes a little, and it is partially covered by an open massive frame of joist-work, on which the potting casks are set upright. These are merely empty sugar hogsheads, without headings, having 8 or 10 holes bored in their bottoms, through each of which the stalk of a plantain leaf is stuck, so as to protrude downwards 6 or 8 inches below the level of the joists, and to rise above the top of the cask. The act of transferring the crude concrete sugar from the crystallizers into these hogsheads, is called potting. The bottom holes, and the spongy stalks stuck in them, allow the molasses to drain slowly downwards into the sunk cistern. In the common mode of procedure, sugar of average quality is kept from 3 to 4 weeks in the curing-house; that which is soft-grained and glutinous, must remain 5 or 6 weeks. The curing-house should be close and warm, to favour the liquefaction and drainage of the viscid caramel.

Out of 120 millions of pounds of raw sugar, which used to be annually shipped by the St. Domingo planters, only 96 millions were landed in France, according to the authority of Dutrone, constituting a loss by drainage in the ships of 20 per cent. The average transport waste at present in the sugars of the British colonies cannot be estimated at less than 12 per cent., or altogether upwards of 27,000 tons! What a tremendous sacrifice of property!

Within these few years a very considerable quantity of sugar has been imported into Great Britain in the state of concentrated cane-juice, containing nearly half its weight of granular sugar, along with more or less molasses, according to the care taken in the boiling operations. I was at first apprehensive that the syrup might undergo some change on the voyage; but among more than a hundred samples which I have analyzed for the custom-house, I have not perceived any traces of fermentation. Since sugar softens in its grain at each successive solution, whatever portion of the crop may be destined for the refiner, should upon no account be granulated in the colonies; but should be transported in the state of a rich cane-syrup to Europe, transferred at once into the blowing-up cistern, subjected there to the reaction of bone black, and passed through bag-filters, or through layers of the coarsely ground black, previously to its final concentration in the vacuum pan. Were this means generally adopted, I am convinced that 30 per cent. would be added to the amount of home-made sugar loaves corresponding to a given quantity of average cane-juice; while 30 per cent., would be taken from the amount of molasses. The saccharine matter now lost by drainage from the hogsheads in the ships, amounting to from 10 to 15 per cent., would, also be saved. The produce of the cane would, on this plan, require less labour in the colonies, and might be exported 5 or 6 weeks earlier than at present, because the period of drainage in the curing-house would be spared.

It does not appear that our sugar colonists have availed themselves of the proper chemical method of counteracting that incipient fermentation of the cane-juice, which sometimes supervenes, and proves so injurious to their products. It is known that grape-must, feebly impregnated with sulphurous acid, by running it slowly into a cask in which a few sulphur matches have been burned, will keep without alteration for a year; and if _must_, so _muted_, is boiled into a syrup within a week or ten days, it retains no sulphureous odour. A very slight muting would suffice for the most fermentable cane-juice: and it could be easily given, by burning a sulphur match within the cistern immediately before charging it from the mill. The cane-juice should, in this case, be heated in the clarifier, so as to expel the sulphurous acid, before adding the temper lime; for otherwise a little calcareous sulphite might be introduced into the sugar. Thus the arescence so prejudicial to the saccharine granulation would be certainly prevented.

An ACCOUNT of SUGAR Imported into the United Kingdom during the years ending 5th January, 1837, and 5th January, 1838.

+------------------------------+-----------------------------------+ | | Quantities imported. | | +-----------------+-----------------+ | | 1837. | 1838. | | +-----------------+-----------------+ | | Cwt. qr. lb.| Cwt. qr. lb.| |Sugar, unrefined; viz.--of | | | |the British possessions in | | | |America |3,600,516 3 2 |3,304,092 2 2 | |Of Mauritius | 497,303 0 8 | 537,054 1 21 | |East India British possessions| 152,229 1 13 | 296,677 2 12 | |East India Foreign possessions| 71,464 2 0 | 77,090 0 18 | |Other sorts | 327,647 1 12 | 266,559 2 24 | | +-----------------+-----------------+ |Total |4,649,161 0 7 |4,481,474 1 21 | +------------------------------+-----------------+-----------------+

+------------------------------+-----------------------------------+ | | Quantities entered for Home | | | Consumption. | | +-----------------+-----------------+ | | 1837. | 1838. | | +-----------------+-----------------+ | | Cwt. qr. lb.| Cwt. qr. lb.| |Sugar, unrefined; viz.--of | | | |the British possessions in | | | |America |3,296,641 1 19 |3,562,703 1 24 | |Of Mauritius | 518,228 0 5 | 522,348 3 11 | |East India British possessions| 110,236 2 0 | 270,146 1 2 | |East India Foreign possessions| 20 3 18 | 3 3 11 | |Other sorts | 31 1 6 | 37 3 10 | | +-----------------+-----------------+ |Total |3,925,140 0 20 |4,355,240 1 2 | +------------------------------+-----------------+-----------------+

+------------------------------+---------------------+ | |Gross amount of Duty | | | received. | | +----------+----------+ | | 1837. | 1838. | | +----------+----------+ | | _£_. | _£_. | |Sugar, unrefined; viz.--of | | | |the British possessions in | | | |America |3,956,879 |4,275,207 | |Of Mauritius | 621,596 | 626,131 | |East India British possessions| 176,376 | 368,672 | |East India Foreign possessions| 66 | 12 | |Other sorts | 41 | 95 | | +----------+----------+ |Total |4,754,958 |5,270,117 | +------------------------------+----------+----------+

An ACCOUNT of SUGAR Exported in the year ended 5th January, 1838, compared with the Exports of the preceding Year.

+----------------------+-----------------+-----------------+ | | 1837. | 1838. | | +-----------------+-----------------+ | | Cwts. qrs. lbs.| Cwts. qrs. lbs.| |Sugar, of the British | | | | possessions | | | | in America | 8,774 1 15 | 9,267 0 21 | | Mauritius | 2,687 3 14 | 3,065 0 19 | | East India, of | | | | British posses-| | | | sions | 22,290 3 16 | 13,283 0 22 | | Foreign posses-| | | | sions | 52,384 0 4 | 68,252 2 18 | | Other sorts |191,961 0 20 |354,513 1 23 | +----------------------+-----------------+-----------------+

Syrup intended for forming clayed sugar must be somewhat more concentrated in the teache, and run off into a copper cooler, capable of receiving three or four successive skippings. Here it is stirred to ensure uniformity of product, and is then transferred by ladles into conical moulds, or _formes_, made of coarse pottery, having a small orifice at the apex, which is stopped with a plug of wood wrapped in a leaf of maize. These pots are arranged with the base upwards. As their capacity, when largest, is greatly less than that of the smallest potting-casks, and as the process lasts several weeks, the claying-house requires to have very considerable dimensions. Whenever the syrup is properly granulated, which happens usually in about 18 or 20 hours, the plugs are removed from the apices of the cones, and each is set on an earthen pot to receive the drainings. At the end of 24 hours, the cones are transferred over empty pots, and the molasses contained in the former ones is either sent to the fermenting-house or sold. The claying now begins, which consists in applying to the smoothed surface of the sugar at the base of the cone, a plaster of argillaceous earth, or tolerably tenacious loam in a pasty state. The water diffused among the clay escapes from it by slow infiltration, and descending with like slowness through the body of the sugar, carries along with it the residuary viscid syrup which is more readily soluble than the granulated particles. Whenever the first magma of clay has become dry, it is replaced by a second; and this occasionally in its turn by a third, whereby the sugar cone gets tolerably white and clean. It is then dried in a stove, cut transversely into _frusta_, crushed into a coarse powder on wooden trays, and shipped off for Europe. Clayed sugars are sorted into different shades of colour according to the part of the cone from which they were cut; under the denomination in French commerce of _premier_, _second_, _troisième_, _petit_, _commun_, and _tête_; the last or the tip being an indifferent article. The clayed sugar of Cuba is called Havannah sugar, from the name of the shipping port.

Clayed sugar can be made only from the ripest cane-juice, for that which contains much gluten would be apt to get too much burned by the ordinary process of boiling, to bear the claying operation. The syrups that run off from the second, third, and fourth application of the clay-paste, are concentrated afresh in a small building apart, called the refinery, and yield tolerable sugars. Their drainings go to the molasses cistern. The cones remain for 20 days in the claying-house, before the sugar is taken out of them.

Claying is seldom had recourse to in the British plantations, on account of the increase of labour, and diminution of weight in the produce, for which the improvement in quality yields no adequate compensation. Such, however, was the esteem in which the French consumers held clayed sugar, that it was prepared in 400 plantations of St. Domingo alone.

SUGAR REFINING.

Raw, or muscovado sugar, as imported from the colonies, is contaminated more or less with gluten, lime, but particularly _caramel_, which give its grains a yellow brown tint, an empyreumatic odour, and a soft clammy feel in the hand. If such sugar be dissolved in water, and the syrup be evaporated by a gentle heat, it will afford a sugar of still inferior quality and appearance. This rapid deterioration is in some measure owing to the injurious operation of a prolonged heat upon the crystalline structure, but chiefly to the chemical reaction of the glutinous ferment and lime upon the sugar. The first care of the refiner should therefore be the immediate abstraction of these noxious alteratives, which he effects by the process called _meltings_; that is, mixing up the sugar in a pan with hot water or steam into a pap, and transferring this pap into large sugar-moulds. Whenever these become cool, their points are unplugged, and they are set to drain for a few days in a warm apartment. Sugar thus cleansed is well prepared for the next refining process; which consists in putting it into a large square copper cistern along with some lime-water, (a little bullock’s blood,) and from 5 to 20 per cent. of bone black, and blowing it up with steam; or, in other words, injecting steam through the mixture from numerous orifices in copper pipes laid along the bottom and sides of the vessel. Under the influence of the heat and agitation thus occasioned, the saccharine matter is perfectly dissolved and incorporated with the albumen of the blood and the bone black. Instead of the blood, many refiners employ a mixture of gelatinous alumina and gypsum, called _finings_, prepared by adding a solution of alum to a body of lime-water, collecting, washing, and draining the precipitate upon a filter. Other refiners use both the blood and finings, with advantage. Bone black is now very frequently employed by the sugar-refiner, not in a fine meal, but in a granular state, like corned gunpowder, for the purpose of decolouring his syrups; in which case, he places it in a box, in a stratum 8 or 10 inches thick, and makes the syrup percolate downwards through it, into a cistern placed beneath. By this means it is deprived of colour, and forms the _claircé_ of the French refiner. When the blowing up cistern is charged with sugar, finely ground bone black, and blood, the mixture must be passed through a proper system of filters. That now most in use is the creased bag filter, represented in _figs._ 1084, 1085, 1086.

The apparatus consists of an upright square wooden case _a_, _a_, about 6 or 8 feet high, furnished with a door of admission to arrange the interior objects; beneath is a cistern with an educting-pipe for receiving and carrying off the filtered liquor; and above the case is another cistern _e_, which, like the rest, is lined with tinned sheet copper. Into the upper cistern, the syrup mixed with animal charcoal is introduced, and passes thence into the mouths _e_, _e_, of the several filters _d_, _d_. These consist, each of a bag of thick tweeled cotton cloth, about 12 or 15 inches in diameter, and 6 or 8 feet long, which is inserted into a narrow bottomless bag of canvas, about 5 inches in diameter, for the purpose of folding the filter-bag up into a small space, and thus enabling a great extent of filtering surfaces to be compressed into one box. The orifice of each compound bag is tied round a conical brass month-piece or nozzle _e_, which screws tight into a corresponding opening in the copper bottom of the upper cistern. From 40 to 60 bags are mounted in each filter case. The liquor which first passes is generally tinged a little with the bone black, and must be pumped back into the upper cistern, for refiltration. In cold weather the interior of the case may be kept warm by a proper distribution of steam-pipes. _Fig._ 1085. shows one mode of forming the funnel-shaped nozzles of the bags, in which they are fixed by a bayonet catch. _Fig._ 1086. shows the same made fast by means of a screwed cap, which is more secure.

The next process in sugar-refining is the evaporation of the clarified syrup to the granulating or crystallizing pitch. The more rapidly this is effected, and with the less scorching injury from fire, the better and greater is the product in sugar-loaves. No apparatus answers the refiner’s double purpose of safety and expedition so well as the vacuum-pan of Howard.

_Fig._ 1087. shows the structure of a single vacuum-pan. The horizontal diameter of the copper spheroid A, is not less than 5 feet; the depth of the under hemisphere is at least 18 inches from the level of the plane; and the height of the dome-cover is 2 feet. The two hemispheres (of which the inferior one is double, or has a steam-jacket,) are put together by bolts and screws, with packing between the flanges to preserve the joints tight against atmospheric pressure. The jacket of the lower hemisphere forms the case of the steam, which communicates heat to the syrup enclosed in the inner hemisphere. In general, the pans contain, when filled to the flange, 100 gallons of syrup, and yield about 11 cwt. of granulated sugar, at every charge.

A, represents the vacuum spheroid; B, the neck with the lid. From the side of B, a pipe passes into the lower extremity of the bent pipe C, D, which terminates in the vertical pipe E, connected with the vacuum main-pipe K, proceeding horizontally from the air-pump (not shown in the figure). At the top of E, a valve, movable by a screw H, is placed for establishing or cutting off the connexion with the air-pump at pleasure. Behind F, is the measure cistern, from which the successive charges are admitted into the pan. This measure is filled with the clear syrup, by opening the stopcock I, on the pipe under the ceiling, which communicates with the filter-cistern placed above. G is the valve or plug-hole, at the bottom of the pan, for discharging the granulating syrup. This plug is opened by means of a powerful lever attached to it; the connexion with the air-pump being previously intercepted. L, is the barometer, or manometer, for showing the state of the vacuum corresponding to the temperature. N, N, is a cistern-pipe for receiving any little syrup which may accidentally boil over the neck B. Its contents are let off by a stopcock at its bottom from time to time. M shows the place of the _proof-stick_, an ingenious brass rod for taking out a sample of syrup without admitting air. See _infrà_.

The charging-cistern contains about 20 gallons. This quantity of syrup being first admitted, and brought to a certain pitch of concentration, a second measure is introduced, the inspissation of which is supposed by some refiners to cause an agglomeration of saccharine matter round the first crystalline particles. The repetition of this process for two or three times is imagined to produce the large brilliant grain of vacuum-pan sugar. This hypothesis is more specious than sound, because the granulating syrup discharged from the pan is subjected to a heat of 180° or 190° in the subjacent steam-cased receiver, whereby the granulations are again reduced to a very small size. Into this receiver, two or three skippings or discharges of the pan are admitted in succession, and the whole are diligently mixed and agitated by a stirring oar. It is by this process that the granulating tendency is promoted and determined. From this receiver (absurdly enough called a cooler) the moulds are filled in the usual way, by means of copper basins or large ladles.

The case of the under hemisphere of the vacuum-pan is filled with steam, generated under a pressure of four or five pounds on the square inch; the heat of which causes the interior syrup to boil rapidly while the air-pump is kept in action. A small escape-pipe for waste steam must be placed at the opposite side of the case or jacket, to ensure its equal distribution; as also a stopcock below, to let off the water of condensation. The pans are mounted on iron feet, or short pillars, which insulate them from the floor, and allow their whole surface to be inspected, and any flaw to be repaired. The air-pump usually stands in a cold-water cistern, to favour the condensation of the aqueous vapour, which it draws out of the pans; and it is kept in constant action by the steam-engine, being attached to the working-beam of its piston.

_Fig._ 1088. exhibits the general arrangement of the vacuum-pans, and their subsidiary apparatus. Here are shown, on the ground floor, the heaters _e_, _e_, (miscalled coolers), into which the concentrated syrup is let down. These heaters are made of copper, in one piece, surrounded with a cast-iron jacket, bolted at the flange or brim to it. Each pan contains, when full, about 350 gallons, equivalent to nearly 35 cwt. of crystallized sugar. They are furnished with steam-cocks and waste steam-pipes. Under the level of the spheroids _d_, _d_, the horizontal main-pipe is seen, for supplying the cases with steam. In the face of each pan, above the line _b_, _b_, the handle of the proof-stick appears, like that of a stop-cock. The distribution of the measure cisterns, and some other parts of the pans, is slightly varied in this representation from the former. From the bottom of the liquor cisterns C, C, pipes descend to the charging measures _a_, _a_, below. The cisterns C, C, are made of copper, and contain each about 400 gallons. Six tons of refined sugar can be turned out daily in a three-pan house.

_Fig._ 1089. represents in section another form of the vacuum-pan, _a_ is the spheroidal copper vessel, supported by four iron columns _b_, _b_. It may be discharged by means of the pipe _c_, which is secured with a conical valve _d_. This may be opened or shut, by acting on the lever _e_. The lower of the two hemispheres of which the pan is composed is double, and the interstitial space _f_, _f_, is filled with steam by the pipe _g_, as the heating and evaporating agent. _h_, is the steam valve; _i_, the pipe for the efflux of the condensed water. _k_, a tube for the escape of the air at the commencement of the operation. _l_, is an apparatus inserted air-tight into the cover of the vacuum-pan, and which dips down into the syrup; serving to take out a sample of it, without allowing air to enter, and hence called the proof-stick. The construction of this instrument is exhibited in _figs._ 1091, 1092, 1093, 1094, 1095., which will be presently explained. _m_, is the thermometer, which is also plunged into the sugar; behind it, is the barometer. _n_, is the charger or gauge-vessel, filled with the filtered syrup, which it discharges by the pipe _n´_. _o_, is the cover or capital of the vacuum-pan. _o´_, is a safety-valve, through which the air may be admitted, after the completion of the process. _p_, is a bent pipe, slanting downwards, with a stopcock _q_, at its end, to receive the superfluous syrup. The vapour, which is disengaged from the syrup during its concentration, is extracted from the top of the pan into the pipe _r_, passes from this into the vessel _s_, which is divided by a plate of copper into two compartments. The syrup forced over accidentally in the ebullition, goes into the vessel _s_, and passes by the glass tube _t_, into the pipe _p_. The glass tube serves to show the quantity of the syrup that has boiled over, so that it may be drawn off when necessary. For this purpose, the stopcock _u_, of the vessel _v_, must be closed, and _q_ must be opened, in order to fill _v_, while the air contained in it escapes into the pan. The stopcock _q_, being then shut, and _u_, with the little air-cock _x_, opened, the syrup will flow into the large receiver placed beneath it, commonly but erroneously called a cooler; because it is a double copper basin, with steam in the interstitial space. The hot steam rushes from _s_, into the cast-iron vessel _y_, where it is condensed. _z_, is a pipe for introducing the water of condensation through the copper rose _a´_. The condensed water flows through the pipe _b´_, and the valve _e´_, to the air-pump, which receives motion from the shaft of the steam-engine.

The vacuum-pan was originally heated solely by the admission of steam between the double bottom; but of late years the heat has been also applied to the syrup through several coils of pipe placed within the pan, filled with steam at a temperature many degrees above 212° F., sometimes so high as 250°. By this double application of heat, the evaporating power of a pan has been vastly increased. The latest made pans have a considerably flat bottom, _fig._ 1090.; a spiral pipe, laid close upon it; and between the under hemisphere and the upper one, there is a space _a_, _a_, 2-1/2 feet high, to give the syrup room for frothing up without boiling over. The space _b_, of the bottom receives steam of common pressure, and the spiral tubes, of high pressure. A pan like this is now making for a house in London, which is to work off 16 tons of sugar-loaves daily.

The proof-stick, _fig._ 1095., consists of a cylindrical rod, capable of being screwed air-tight into the pan in an oblique direction downwards. The upper or exterior end is open; the under, which dips into the syrup, is closed, and has on one side a slit _a_ (_figs._ 1091, 1092.), or notch, about 1/2 inch wide. In this external tube, there is another shorter tube _b_, capable of moving round in it, through an arc of 180°. An opening upon the under end _e_, corresponds with the slit in the outer tube, so that both may be made to coincide, _fig._ 1091. A. A wooden plug _d_, is put in the interior tube, but so as not to shut it entirely. Upon the upper end there is a projection or pin, which catches in a slit of the inner tube, by which this may be turned round at pleasure. In the lower end of the plug there is a hole _e_, which can be placed in communication with the lateral openings in both tubes. Hence it is possible, when the plug and the inner tube are brought into the proper position, A, _fig._ 1091., to fill the cavity of the wooden rod with the syrup, and to take it out without allowing any air to enter. In order to facilitate the turning of the inner tube within the outer, there is a groove in the under part, into which a little grease may be introduced.

Whenever a proof has been taken, the wooden plug must be placed in reference to the inner tube, as shown in _fig._ 1091. _c_, and then be turned into the position A; when the cavity of the plug will again be filled with syrup. _c_ must be now turned back to the former position, whereby all intercourse with the vacuum-pan is cut off; the plug being drawn out a little, and placed out of communication with the inner tube. The plug is then turned into the position B, drawn out, and the proof examined by the fingers.

TABLE showing the boiling point of syrup, at the corresponding atmospheric pressure within the vacuum-pan:--

Height of the mercury (inches) in one leg of the syphon, above that in the other-- 0·74 0·86 1·01 1·17 1·36 1·57 1·80 2·05 2·36 2·72 3·10 3·52 4·00. Boiling point, Fahr.-- 115° 120° 125° 130° 135° 140° 145° 150° 155° 160° 165° 170° 175°.

The large double steam-basin, which receives several successive skippings of the concentrated granulating syrup, serves to heat it from the temperature of 160° or 170°, at which it leaves the vacuum-pan, up to 200° or thereby, before it is filled out into the moulds; for were it introduced in the cooler state, it would not concrete into sufficiently compact loaves.

The following apparatus is used in many French sugar-houses, for concentrating syrups, called the _swing pan_, or _chaudière à bascule_. It is represented in _fig._ 1096. in elevation, and in _fig._ 1097. in ground plan. _a_, is the pan; _b_, its spout; _c_, the axis or pivot round which it swings, so as to empty itself, when raised behind by the chain _d_; _e_, is the furnace door; _f_, the passage to the fireplace and grate _g_; _h_, _h_, _h_, side flues for conducting the smoke into the chimney.

The duly clarified, concentrated, granulated, and reheated syrup, is transferred, by means of copper basins, from the coolers into conical moulds, made either of brown and somewhat porous earthenware, or of sheet iron, strongly painted. The sizes of the moulds vary, from a capacity of 10 pound _loaves_, to that of 56 pound _bastards_--a kind of soft brown sugar obtained by the concentration of the inferior syrups. These moulds have the orifices at their tips closed with bits of twisted paper, and are set up in rows close to each other, in an airy apartment adjoining the coolers. Here they are left several hours, commonly the whole night, after being filled, till their contents become solid, and they are lifted next morning into an upper floor, kept at a temperature of about 80° by means of steam pipes, and placed each over a pot to receive the syrup drainings--the paper plug being first removed, and a steel wire, called a piercer, being thrust up to clear away any concretion from the tip. Instead of setting the lower portion of the inverted cones in pots, some refiners arrange them in wooden racks, with their apices suspended over longitudinal gutters of lead or zinc, laid with a slight slope upon the floor, and terminating in a sunk cistern. The syrup which flows off spontaneously is called green syrup. It is kept separate. In the course of two or three days, when the drainage is nearly complete, some finely clarified syrup, made from loaf sugar, called _liquor_ by the refiners, is poured to the depth of about an inch upon the base of each cone, the surface having been previously rendered level and solid by an iron tool, called a bottoming trowel. The liquor, in percolating downwards, being already a saturated syrup, can dissolve none of the crystalline sugar, but only the coloured molassy matter; whereby, at each successive liquoring, the loaf becomes whiter, from the base to the apex. A few moulds, taken promiscuously, are emptied from time to time, to inspect the progress of the blanching operation; and when the loaves appear to have acquired as much _colour_, according to the language of refiners, as is wanted for the particular market, they are removed from the moulds, turned on a lathe at the tips, if necessary, set for a short time upon their bases, to diffuse their moisture equally through them, and then transferred into a stove heated to 130° or 140° by steam pipes, where they are allowed to remain for two or three days, till they be baked thoroughly dry. They are then taken out of the stove, and put up in blue paper for sale.

In the above description of sugar-refining, I have said nothing of the process of claying the loaves, because it is now nearly obsolete, and abandoned in all well-appointed sugar-houses. Those of my readers who desire to become acquainted with sugar-refining upon the old plan, may consult my Report made upon the subject to the Honourable HOUSE of COMMONS in July 1833; where they will find every step detailed, and the numerical results stated with minute accuracy. The experiments subservient to that official report were instituted purposely to determine the average yield or product, in double and single refined loaves, lumps, bastards and treacle, which different kinds of sugar would afford per cwt., when refined by decolouring with not more than 5 per cent. of bone black, boiling in an open pan, and clearing the loaves with clay-pap.

BEET-ROOT SUGAR.

The physical characters which serve to show that a beet-root is of good quality, are its being firm, brittle, emitting a creaking noise when cut, and being perfectly sound within; the degree of sweetness is also a good indication. The 45th degree of latitude appears to be the southern limit of the successful growth of beet in reference to the extraction of sugar.

_Extraction of Sugar from the Beet._--The first manipulations to which the beets are exposed, are intended to clear them from the adhering earth and stones, as well as the fibrous roots and portions of the neck. It is desirable to expose the roots, after this operation, to the action of a cylinder washing-machine.

The parenchyma of the beet is a spongy mass, whose cells are filled with juice. The cellular tissue itself, which forms usually only a twentieth or twenty-fifth of the whole weight, consists of ligneous fibre. Compression alone, however powerful, is inadequate to force out all the liquor which this tissue contains. To effect this object, the roots must be subjected to the action of an instrument which will tear and open up the greatest possible number of these cells. Experiments have, indeed, proved, that by the most considerable pressure, not more than 40 or 50 per cent. in juice from the beet can be obtained; whilst the pulp procured by the action of a grater produces from 75 to 80 per cent.

The beet-root rasp of Moulfarine is represented in _figs._ 1098, 1099. _a_, _a_, is the frame-work of the machine; _b_, the feed-plate made of cast iron, divided by a ridge into two parts; _c_, the hollow drum; _d_, its shaft, upon either side of whose periphery nuts are screwed for securing the saw blades _e_, _e_, which are packed tight against each other by means of laths of wood; _f_, is a pinion upon the shaft of the drum, into which the wheel _g_ works, and which is keyed upon the shaft _h_; _i_, is the driving rigger; _k_, pillar of support; _l_, blocks of wood, with which the workman pushes the beet-roots against the revolving-rasp; _m_, the chest for receiving the beet-pap; _n_, the wooden cover of the drum, lined with sheet iron. The drum should make 500 or 600 turns in the minute.

A few years ago, M. Dombasle introduced a process of extracting the juice from the beet without either rasping or hydraulic pressure. The beets were cut into thin slices, by a proper rotatory blade-machine; these slices were put into a macerating cistern, with about their own bulk of water, at a temperature of 212° F. After half an hour’s maceration, the liquor was said to have a density of 2° B., when it was run off into a second similar cistern, upon other beet-roots; from the second, it was let into a third, and so on to a fifth; by which time, its density having risen to 5-1/2°, it was ready for the process of defecation. Juice procured in this way is transparent, and requires little lime for its purification; but it is apt to ferment, or to have its granulating power impaired by the watery dilution. The process has been accordingly abandoned in most establishments.

I have seen the following operations successfully executed in a beet-root factory near Lille, and have since verified their propriety in my own laboratory upon white beets, grown near Mitcham in Surrey. My product was nearly 5 per cent.; it was very fair, and large grained, like the vacuum-pan sugar of Demerara, but without its clamminess.

The roots were washed by a rotatory movement upon a grating made like an Archimedes’ screw, formed round the axis of a squirrel-cage cylinder, which was laid horizontally beneath the surface of water in an oblong trough. It was turned by hand rapidly, with the intervention of a toothed wheel and pinion. The roots, after being sufficiently agitated in the water, were tossed out by the rotation at the end of the cylinder furthest from the winch. They were next hoisted in a basket up through a trap hole into the floor above, by means of a cord and pulley moved by mechanical power; a six-horse steam engine, upon Woolfe’s expansive principle, being employed to do all the heavy work. They were here subjected to the mechanical grater (_rape mécanique_), see _fig._ 1098, 1099., which had, upon its sloping feed-table, two square holes for receiving at least two beets at a time, which were pushed forwards by a square block of wood held in the workman’s hand by means of a strap. The rasp was a drum, having rows of straight saws placed half an inch apart round its periphery, _parallel to the axis_, with teeth projecting about 1/8 of an inch. The space between each pair of saws was filled with a wedge of wood. The steel slips, or saw plates, were half an inch broad, twelve inches long, and serrated on both their longitudinal edges, so that when the one line of teeth was blunted, the other could be turned out. The drum made 750 turns per minute.

The pulp from the rasp fell into a flat trough placed beneath, whence it was shovelled into small bags. Each bag had its mouth folded over, was laid upon a wicker plate, and spread flat with a rolling-pin. The bags and hurdles were then piled in the hydraulic press. There were three presses, of which the two allotted to the first pressure were charged alternately, and the third was reserved for a final and more durable pressure of the _marc_. See PRESS, HYDRAULIC, and STEARINE PRESS.

The juice flowed over the edges of the wicker plates, and fell into the sill-plate of the press, which was furnished with upright borders, like a tray, through whose front side a pipe issued, that terminated in a leathern hose, for conducting the juice into an elevated cistern in the boiling-house. Here one pound of slaked lime was mixed with every four hectolitres (about 88 gallons imp.) of juice. The mixture was made to boil for a little while in a round pan alongside, whence it was decanted into oblong flat filters, of blanket stuff. The filtered liquor, which had in general a spec. gravity of 15° Baumé, (about double that of the fresh juice), was now briskly concentrated by boiling, in an oblong pan, till it acquired the density of 28° B. The fire being damped with raw coal, the syrup was run off rapidly by a stopcock into a large basin with a swing handle, and immediately replaced by fresh defecated liquor. The basin was carried by two men to the opposite side of the boiling-house, and emptied into a cistern set on a high platform, whose horizontal discharge-pipe was provided with a series (five) of stopcocks, placed respectively over five copper chests (inverted truncated pyramids), containing a thick bed of granular bone black, covered with a perforated copper plate. The hot syrup thus filtered had a pale straw-colour, and was subsequently evaporated in swing pans, _figs._ 1096, 1097., over a brisk fire, in quantities equivalent to half a cwt. of sugar, or four hectolitres of average juice.

MAPLE SUGAR.

The manufacture of sugar from the juice of a species of maple tree, which grow spontaneously in many of the uncultivated parts of North America, appears to have been first attempted about 1752, by some of the farmers of New England, as a branch of rural economy.

The sugar maple, the _Acer saccharinum_ of Linnæus, thrives especially in the states of New York and Pennsylvania, and yields a larger proportion of sugar than that which grows upon the Ohio. It is found sometimes in thickets which cover five or six acres of land; but it is more usually interspersed among other trees. They are supposed to arrive at perfection in forty years.

The extraction of maple sugar is a great resource to the inhabitants of districts far removed from the sea; and the process is very simple. After selecting a spot among surrounding maple trees, a shed is erected, called the _sugar-camp_, to protect the boilers and the operators from the vicissitudes of the weather. One or more augers, three-fourths of an inch in diameter; small troughs for receiving the sap; tubes of elder or sumach, 8 or 10 inches long, laid open through two-thirds of their length, and corresponding in size to the auger-bits; pails for emptying the troughs, and carrying the sap to the camp; boilers capable of holding 15 or 16 gallons; moulds for receiving the syrup inspissated to the proper consistence for concreting into a loaf of sugar; and, lastly, hatchets to cut and cleave the fuel, are the principal utensils requisite for this manufacture. The whole of February and beginning of March are the sugar season.

The trees are bored obliquely from below upwards, at 18 or 20 inches above the ground, with two holes 4 or 5 inches asunder. Care must be taken that the auger penetrates no more than half an inch into the alburnum, or white bark; as experience has proved that a greater discharge of sap takes place at this depth than at any other. It is also advisable to perforate in the south face of the trunk.

The trough, which contains from two to three gallons, and is made commonly of white pine, is set on the ground at the foot of each tree, to receive the sap which flows through the two tubes inserted into the holes made with the auger; it is collected together daily, and carried to the camp, where it is poured into casks, out of which the boilers are supplied. In every case, it ought to be boiled within the course of two or three days from flowing out of the tree, as it is liable to run quickly into fermentation, if the weather become mild. The evaporation is urged by an active fire, with careful skimming during the boiling; and the pot is continually replenished with more sap, till a large body has at length assumed a syrupy consistence. It is then allowed to cool, and passed through a woollen cloth, to free it from impurities.

The syrup is transferred into a boiler to three-fourths of its capacity, and it is urged with a brisk fire, till it acquires the requisite consistence for being poured into the moulds or troughs prepared to receive it. This point is ascertained, as usual, by its exhibiting a granular aspect, when a few drops are drawn out into a thread between the finger and the thumb. If in the course of the last boiling, the liquor froth up considerably, a small bit of butter or fat is thrown into it. After the molasses have been drained from the concreted loaves, the sugar is not at all deliquescent, like equally brown sugar from the cane. Maple sugar is in taste equally agreeable with cane sugar, and it sweetens as well. When refined, it is equally fair with the loaf sugar of Europe.

The period during which the trees discharge their juices is limited to about six weeks. Towards the end of the flow, it is less abundant, less saccharine, and more difficult to be crystallized.

QUANTITY of SUGAR brought into the Markets of the World, in the year 1838.

Tons. British West Indies 160,000 Mauritius, 35,000; and British East Indies, 20,000 55,000 Java 36,000 Manilla and Siam 30,000 Dutch West Indies 25,000 St. Thomas and St. Croix 7,000 Martinique and Guadaloupe 80,000 Bourbon 20,000 Cuba 100,000 Brazils 95,000 From Beet-root, in France and Belgium 65,000 United States 65,000 ------- 738,000[65]

[65] For this important table, I am indebted to James Cook, Esq., of Mincing-lane.

SUGAR OF LEAD, properly _Acetate of lead_, (_Acetate de plomb_; _Sel de Saturne_, Fr.; _Essigsaures Bleioxyd_, _Bleizucker_, Germ.) is prepared by dissolving pure litharge, with heat, in strong vinegar, made of malt, wood, or wine, till the acid be saturated. A copper boiler, rendered negatively electrical by soldering a strap of lead within it, is the best adapted to this process on the great scale. 325 parts of finely ground and sifted oxide of lead, require 575 parts of strong acetic acid, of spec. grav. 7° Baumé, for neutralization, and afford 960 parts of crystallized sugar of lead. The oxide should be gradually sprinkled into the moderately hot vinegar, with constant stirring, to prevent adhesion to the bottom; and when the proper quantity is dissolved, the solution may be weakened with some of the washings of a preceding process, to dilute the acetate, after which the whole should be heated to the boiling point, and allowed to cool slowly, in order to settle. The limpid solution is to be drawn off by a syphon, concentrated by boiling to the density of 32° B., taking care that there be always a faint excess of acid, to prevent the possibility of any basic salt being formed, which would interfere with the formation of regular crystals. Should the concentrated liquor be coloured, it may be whitened by filtration through granular bone black.

Stoneware vessels, with salt glaze, answer best for crystallizers. Their edges should be smeared with candle-grease, to prevent the salt creeping over them by _efflorescent vegetation_. The crystals are to be drained, and dried in a stove-room very slightly heated. It deserves remark, that linen, mats, wood, and paper, imbued with sugar of lead, and strongly dried, readily take fire, and burn away like tinder. When the motherwaters cease to afford good crystals, they should be decomposed by carbonate of soda, or by lime skilfully applied, when a carbonate or an oxide will be obtained, fit for treating with fresh vinegar. The supernatant acetate of soda may be employed for the extraction of pure acetic acid.

A main point in the preparation of sugar of lead, is to use a strong acid; otherwise much time and acid are wasted in concentrating the solution. This salt crystallizes in colourless, transparent, four and six sided prisms, from a moderately concentrated solution; but from a stronger solution, in small needles, which have a yellow cast if the acid has been slightly impure. It has no smell, a sweetish astringent metallic taste, a specific gravity of 2·345; it is permanent in the air at ordinary temperatures, but effloresces when heated to 95°, with the loss of its water of crystallization and some acid, falling into a powder, which passes, in the air, slowly into carbonate of lead. The crystals dissolve in 1-1/2 times their weight of water at 60°, but in much less of boiling water, and in 8 parts of alcohol. The solution feebly reddens litmus paper, but has an alkaline reaction upon the colours of violets and turmeric. The constituents of the salt are, 58·71 oxide of lead, 27·08 acetic acid, and 14·21 water, in 100.

Acetate of lead is much used in calico-printing. It is poisonous, and ought to be prepared and handled with attention to this circumstance.

There are two subacetates of lead; the first of which, the ter-subacetate, has three atoms of base to one of acid, and is the substance long known by the name of Goulard’s extract. It may be obtained by digesting with heat a solution of the neutral acetate, upon pure litharge or massicot. The solution affords white crystalline scales, which do not taste so sweet as sugar of lead, dissolve in not less than 30 parts of water, are insoluble in alcohol, and have a decided alkaline reaction upon test paper. Carbonic acid, transmitted through the solution, precipitates the excess of the oxide of lead, in the state of a carbonate, a process long ago prescribed by Thenard for making white-lead. This subacetate consists of 88·66 of oxide, and 13·34 acid, in 100 parts. It is employed for making the orange sub-chromate of lead, as also sometimes in surgery.

A _sex-subacetate_, containing six atoms of base, may be obtained by adding ammonia in excess to a solution of the preceding salt, and washing the precipitate with dilute water of ammonia. A white powder is thus formed, that dissolves sparingly in cold water, but gives a solution in boiling water, from which white silky needles are deposited. It consists of 92·86 oxide, and 7·14 acid.

SULPHATES, are saline compounds of sulphuric acid with oxidized bases. The minutest quantity of them present in any solution, may be detected by the precipitate, insoluble in nitric or muriatic acid, which they afford with nitrate or muriate of baryta. They are mostly insoluble in alcohol.

SULPHATE OF ALUMINA AND POTASSA, is alum.

SULPHATE OF AMMONIA, is a salt sometimes formed by saturating the ammonia liquor of the gas-works with sulphuric acid; and it is employed for making carbonate of ammonia. See AMMONIA and SAL AMMONIAC.

SULPHATE OF BARYTA, is the mineral called heavy-spar, which frequently forms the gangue or vein-stone of lead and other metallic ores.

SULPHATE OF COPPER, _Roman or Blue Vitriol_ (_Vitriol de Chypre_, Fr.; _Kupfervitriol_, Germ.); is a salt composed of sulphuric acid and oxide of copper, and may be formed by boiling the concentrated acid upon the metal, in an iron pot. It is, however, a natural product of many copper mines, from which it flows out in the form of a blue water, being the result of the infiltration of water over copper pyrites, which has become oxygenated by long exposure to the air in subterranean excavations. The liquid is concentrated by heat in copper vessels, then set aside to crystallize. The salt forms in oblique four-sided tables, of a fine blue colour; has a spec. gravity of 2·104; an acerb, disagreeable, metallic taste; and, when swallowed, it causes violent vomiting. It becomes of a pale dirty blue, and effloresces slightly, on long exposure to the air; when moderately heated, it loses 36 per cent. of water, and falls into a white powder. It dissolves in 4 parts of water, at 60°, and in 2 of boiling water, but not in alcohol; the solution has an acid reaction upon litmus paper. When strongly ignited, the acid flies off, and the black oxide of copper remains. The constituents of crystallized sulphate of copper are--oxide, 31·80; acid, 32·14; and water, 36·06. Its chief employment in this country is in dyeing, and for preparing certain green pigments. See SCHEELE’S and SCHWEINFURTH GREEN. In France, the farmers sprinkle a weak solution of it upon their grains and seeds before sowing them, to prevent their being attacked by birds and insects.

SULPHATE OF IRON, _Green vitriol_, _Copperas_ (_Couperose verte_, Fr.; _Eisenvitriol_, _Schwefelsaures Eisenoxydul_, Germ.); is a crystalline compound of sulphuric acid and protoxide of iron; hence called, by chemists, the protosulphate; consisting of, 26·10 of base, 29·90 of acid, and 44·00 of water, in 100 parts; or of 1 prime equivalent of protoxide, 36, + 1 of acid, 40, + 7 of water, 63, = 139. It may be prepared by dissolving iron to saturation in dilute sulphuric acid, evaporating the solution till a pellicle forms upon its surface, and setting it aside to crystallize. The copperas of commerce is made in a much cheaper way, by stratifying the pyrites found in the coal measures (_Vitriolkies_ and _Strahlkies_ of the Germans), upon a sloping puddled platform of stone, leaving the sulphuret exposed to the weather, till, by the absorption of oxygen, it effloresces, lixiviating with water the supersulphate of iron thus formed, saturating the excess of acid with plates of old iron, then evaporating and crystallizing. The other pyrites, which occurs often crystallized, called by the Germans _Schwefelkies_ or _Eisenkies_, must be deprived of a part of its sulphur by calcination, before it acquires the property of absorbing oxygen from the atmosphere, and thereby passing from a bisulphuret into a bisulphate. Alum schist very commonly contains vitriolkies, and affords, after being roasted and weather-worn, a considerable quantity of copperas, which must be carefully separated by crystallization from the alum.

This liquor used formerly to be concentrated directly in leaden vessels; but the first stage of the operation is now carried on in stone canals of considerable length, vaulted over with bricks, into which the liquor is admitted, and subjected at the surface to the action of flame and heated air, from a furnace of the reverberatory kind, constructed at one end, and discharging its smoke by a high chimney raised at the other. See SODA MANUFACTURE. Into this oblong trough, resting on dense clay, and rendered tight in the joints by water-cement, old iron is mixed with the liquor, to neutralize the excess of acid generated from the pyrites, as also to correct the tendency to superoxidizement in copperas, which would injure the fine green colour of the crystals. After due concentration and saturation in this surface evaporator, the solution is run off into leaden boilers, where it is brought to the proper density for affording regular crystals, which it does by slow cooling, in stone cisterns.

Copperas forms sea-green, transparent, rhomboidal prisms, which are without smell, but have an astringent, acerb, inky taste; they speedily become yellowish-brown in the air, by peroxidizement of the iron, and effloresce in a warm atmosphere: they dissolve in 1·43 parts of water at 60°, in 0·27 at 190°, and in their own water of crystallization at a higher heat. This salt is extensively used in dyeing black, especially hats, in making ink and prussian blue, for reducing indigo in the blue vat, in the China blue dye, for making the German oil of vitriol, and in many chemical and medicinal preparations.

There is a persulphate and subpersulphate of iron, but they belong to the domain of chemistry. The first may be formed, either by dissolving with heat one part of red oxide of iron (colcothar) in one-and-a-half of concentrated sulphuric acid, or by adding some nitric acid to a boiling-hot solution of copperas. It forms with galls and logwood a very black ink, which is apt to become brown-black. When evaporated to dryness, it appears as a dirty white pulverulent substance, which is soluble in alcohol. It consists, in 100 parts, of 39·42 of red oxide of iron, and 60·58 sulphuric acid.

Hydrated peroxide of iron, prepared by precipitation with alkali from solution of the persulphate, is an excellent antidote against poisoning by arsenic. A French _peruquier_, who had swallowed two drams of arsenious acid, was, after an interval of twenty minutes, treated with the oxide precipitated from 6 ounces of that salt by caustic potash. It was diffused in 20 quarts of weak syrup, and administered in successive doses. After repeated vomiting and purging, the patient felt no more pain, and was pronounced by the physician to be quite convalescent.

In the copperas and alum works, a very large quantity of ochrey sediment is obtained; which is a peroxide of iron, containing a little sulphuric acid and alumina. This deposit, calcined in reverberatory hearths, becomes of a bright-red colour; and when ground and elutriated, in the same way as is described under _white lead_, forms a cheap pigment, in very considerable demand, called _English red_, in the French market.

Colcothar of Vitriol, and Crocus of Mars, are old names for red oxide of iron. This brown-red powder is obtained in its purest state, by calcining dried sulphate of iron in a furnace till all its acid be expelled, and its base become peroxidized. It must be levigated, elutriated, and dried. This powder is employed extensively in the steel manufacture, for giving the finishing lustre to fine articles; it is used by silversmiths under the name of plate powder and _rouge_; and by the opticians for polishing the specula of reflecting telescopes. Much of the _crocus_ in the market, is made, however, from the copperas and alum sediments, and is greatly inferior to the article prepared by the last process. The finest _rouge_ is made by precipitating the oxide with soda, then washing and calcining the powder.

An excellent powder for applying to razor-strops, is made by igniting together in a crucible equal parts of well-dried copperas and sea salt. The heat must be slowly raised and well regulated, otherwise the materials will boil over in a pasty state, and the product will be in a great measure lost. When well made, out of contact of air, it has the brilliant aspect of plumbago. It has a satiny feel, and is a true _fer olegiste_, similar in composition to the Elba iron ore. It requires to be ground and elutriated; after which it affords, on drying, an impalpable powder, that may be either rubbed on a strop of smooth buff leather, or mixed up with hog’s-lard or tallow into a stiff cerate.

SULPHATE OF LIME. See GYPSUM.

SULPHATE OF MAGNESIA, _Epsom Salt_ (_Sel amer_, Fr.; _Bittersalz_, Germ.); exists in sea-water, as also in the waters of Saidschütz, Sedlitz, and Püllna; and in many saline springs, besides Epsom in Surrey, whence it has derived its trivial name, and from which it was first extracted, in the year 1695, and continued to be so, till modern chemistry pointed out cheaper and more abundant sources of this useful purgative salt. The sulphate of magnesia, occasionally found effloresced on the surface of minerals in crystalline filaments, was called _haarsalz_ (hair salt) by the older writers. The bittern of the Scotch sea-salt works is muriate of magnesia, mixed, with a little sulphate of magnesia and chloride of sodium. If the proper decomposing quantity (found by trial) of sulphate of soda be added to it, and the mixed solution be evaporated at the temperature of 122° F., chloride of sodium will form by double affinity, and fall down in cubical crystals; while the solution of sulphate of magnesia which remains, being evaporated to the proper point, will afford regular crystals in four-sided prisms with four-sided acuminations. Or, if bittern be treated in a retort with the equivalent quantity of sulphuric acid, the muriatic acid may be distilled off into a series of Woulfe’s bottles, and the sulphate of magnesia, soda, and lime, will remain in the retort, from which mixture the sulphate of magnesia may be separated by filtration and crystallization.

Magnesian limestone being digested with as much muriatic acid as will dissolve out its lime only, will, after washing, afford, with the equivalent quantity of sulphuric acid, a pure sulphate of magnesia; and this is certainly the simplest and most profitable process for manufacturing this salt upon the great scale. Many prepare it directly, by digesting upon magnesian limestone the equivalent saturating quantity of dilute sulphuric acid. The sulphate of lime being separated by subsidence, the supernatant solution of sulphate of magnesia is evaporated and crystallized.

This salt is composed of, magnesia 16·72, sulphuric acid 32·39, and water 50·89. When free from muriate, it tends to effloresce in the air. It dissolves in 4 parts of water at 32°, in 3 parts at 60°, in 1·4 at 200°, and in its own water of crystallization at a higher heat.

SULPHATE OF MANGANESE, is prepared on the great scale for the calico-printers, by exposing the peroxide of the metal and pitcoal ground together, and made into a paste with sulphuric acid, to a heat of 400° F. On lixiviating the calcined mass, a solution of the salt is obtained, which is to be evaporated and crystallized. It forms pale amethyst-coloured prisms, which have an astringent bitter taste, dissolve in 2-1/2 parts of water, and consist of, protoxide of manganese 31·93, sulphuric acid 35·87, and water 32·20, in 100 parts.

SULPHATE OF MERCURY, is a white salt which is used in making corrosive sublimate. See MERCURY. The subsulphate, called _Turbith Mineral_, is a pale yellow pigment, and may be prepared by washing the white sulphated peroxide with hot water, which resolves it into the soluble supersulphate, and the insoluble subsulphate, or _Turbith_. It is poisonous.

SULPHATE OF POTASSA, is obtained by first igniting and then crystallizing the residuum of the distillation of nitric acid from nitre.

SULPHATE OF SODA, is commonly called Glauber’s salt, from the name of the chemist who first prepared it. It is obtained by igniting and then crystallizing the residuum of the distillation of muriatic acid from common salt. It crystallizes in channelled 6-sided prisms. See SODA MANUFACTURE.

SULPHATE OF ZINC, called also _White Vitriol_, is commonly prepared in the Harz, by washing the calcined and effloresced sulphuret of zinc or blende, on the same principle as green and blue vitriol are obtained from the sulphurets of iron and copper. Pure sulphate of zinc may be made most readily by dissolving the metal in dilute sulphuric acid, evaporating and crystallizing the solution. It forms prismatic crystals, which have an astringent, disagreeable, metallic taste; they effloresce in a dry air, dissolve in 2·3 parts of water at 60°, and consist of--oxide of zinc, 28·29; acid, 28·18; water, 43·53. Sulphate of zinc is used for preparing drying oils for varnishes, and in the reserve or resist pastes of the calico-printer.

SULPHITES, are a class of salts, consisting of sulphurous acid, combined in equivalent proportions with the oxidized bases.

SULPHOSELS, is the name given by Berzelius to a class of salts which may be prepared as follows:--1. Dissolve a salt consisting of an oxide and an acid (an _oxisalt_), in a very small quantity of water, and pass through the solution a stream of sulphuretted hydrogen, till the salt be entirely decomposed. In this operation, the _oxisalt_ is transformed into a _sulphosalt_, by the sulphur of the compound gas; while its hydrogen forms water with the oxygen of the saline base. This process is applicable only to the metallic salts; and among these, not to the nitrates, carbonates, or phosphates. 2. Another method of preparing _sulphosalts_ is, to add to a watery solution of sulphuret of potassium, an electro-negative metallic sulphuret, which will dissolve in the liquid till the sulphuret of potassium be saturated. This saline compound is to be employed to effect double decompositions with the oxisalts; that is, to convert the radical of another base, combined with an _oxacid_, into a sulphosalt. 3. If the electro-negative sulphuret be put in powder into a solution of the hydrosulphuret of potassa, it will dissolve and expel the sulphuretted hydrogen with effervescence; just as carbonic acid is displaced by a stronger acid. For his other three methods of preparing _sulphosalts_, see his _Elements_, vol. iii. p. 336, Fr. translation.

SULPHUR; _Brimstone_ (_Soufre_, Fr.; _Schwefel_, Germ.); is a simple combustible, solid, non-metallic, of a peculiar yellow colour, very brittle, melting at the temperature of 226° Fahr., and possessing, after it has been fused, a specific gravity of 1·99. When held in a warm hand, a roll of sulphur emits a crackling sound, by the fracture of its interior parts; and when it is rubbed, it emits a peculiar well-known smell, and acquires at the same time negative electricity. When heated to the temperature of 560° F. it takes fire, burns away with a dull blue flame of a suffocating odour, and leaves no residuum. When more strongly heated, sulphur burns with a vivid white flame. It is not affected by air or water.

Sulphur is an abundant product of nature; existing sometimes pure or merely mixed, and at others in intimate chemical combination with oxygen, and various metals, forming sulphates and sulphurets. See Ores of COPPER, IRON, LEAD, &c., under these metals.

_Fig._ 1100. represents one of the cast-iron retorts used at Marseilles for refining sulphur, wherein it is melted and converted into vapours, which are led into a large chamber for condensation. The body _a_, of the retort is an iron pot, 3 feet in diameter outside, 22 inches deep, half an inch thick, which weighs 14 cwt., and receives a charge of 8 cwt. of crude sulphur. The grate is 8 inches under its bottom, whence the flame rises and plays round its sides. A cast-iron capital _b_, being luted to the pot, and covered with sand, the opening in front is shut with an iron plate. The chamber _d_, is 23 feet long, 11 feet wide, and 13 feet high, with walls 32 inches thick. In the roof, at each gable, valves or flap-doors, _e_, 10 inches square, are placed at the bottom of the chimney _c_. The cords for opening the valves are led down to the side of the furnace. The entrance to the chamber is shut with an iron door. In the wall opposite to the retorts, there are two apertures near the floor, for taking out the sulphur. Each of the two retorts belonging to a chamber is charged with 7-1/2 or 8 cwts. of sulphur; but one is fired first, and with a gentle heat, lest the brimstone froth should overflow; but when the fumes begin to rise copiously, with a stronger flame. The distillation commences within an hour of kindling the fire, and is completed in six hours. Three hours after putting fire to the first retort, the second is in like manner set in operation.

When the process of distillation is resumed, after having been some time suspended, explosions may be apprehended, from the presence of atmospherical air; to obviate the danger of which, the flap-doors must be opened every 10 minutes; but they should remain closed during the setting of the retorts, and the reflux of sulphurous fumes or acid should be carried off by a draught-hood over the retorts. The distillation is carried on without interruption during the week, the charges being repeated four times in the day. By the third day, the chamber acquires such a degree of heat as to preserve the sulphur in a liquid state; on the sixth, its temperature becoming nearly 300° F., gives the sulphur a dark hue, on which account the furnace is allowed to cool on the Sunday. The fittest distilling temperature is about 248°. The sulphur is drawn off through two iron pipes cast in the iron doors of the orifices on the side of the chamber opposite to the furnace. The iron stoppers being taken out of the mouths of the pipes, the sulphur is allowed to run along an iron spout placed over red-hot charcoal, into the appropriate wooden moulds.

_Native sulphur_ in its pure state is solid, brittle, transparent, yellow, or yellow bordering on green, and of a glassy lustre when newly broken. It occurs frequently in crystalline masses, and sometimes in complete and regular crystals, which are all derivable from the rhomboidal octahedron. The fracture is usually conchoidal and shining. Its specific gravity is 2·072, exceeding somewhat the density of melted sulphur. It possesses a very considerable refractive power; and doubles the images of objects even across two parallel faces. Sulphur, crystallized by artificial means, presents a very remarkable phenomenon; for by varying the processes, crystals are obtained whose forms belong to two different systems of crystallization. The red tint, so common in the crystals of Sicily, and of volcanic districts, has been ascribed by some mineralogists to the presence of realgar, and by others to iron; but Stromeyer has found the sublimed orange-red sulphur of Vulcano, one of the Lipari islands, to result from a natural combination of sulphur and selenium.

It is extracted from the minerals containing it, at Solfatara, by the following process:--

Ten earthen pots, of about a yard in height, and 4-1/2 gallons imperial in capacity, bulging in the middle, are ranged in a furnace called a gallery; five being set on the one side, and five on the other. These are so distributed in the body of the walls of the gallery, that their belly projects partly without, and partly within, while their top rises out of the vault of the roof. The pots are filled with lumps of the sulphur ore of the size of the fist; their tops are closed with earthenware lids, and from their shoulder proceeds a pipe of about 2 inches diameter, which bends down, and enters into another covered pot, with a hole in its bottom, standing over a tub filled with water. On applying heat to the gallery, the sulphur melts, volatilizes, and runs down in a liquid state into the tubs, where it congeals. When one operation is finished, the pots are re-charged, and the process is repeated.

In Saxony and Bohemia, the sulphurets of iron and copper are introduced into large earthenware pipes, which traverse a furnace-gallery; and the sulphur exhaled flows into pipes filled with cold water, on the outside of the furnace. 900 parts of sulphuret afford from 100 to 150 of sulphur, and a residuum of metallic protosulphuret. See METALLURGY and COPPER.

Volcanic sulphur is purer than that extracted from pyrites; and as the latter is commonly mixed with arsenic, and some other metallic impregnations, sulphuric acid made of it would not answer for many purposes of the arts; though a tolerably good sulphuric acid may be made directly from the combustion of pyrites, instead of sulphur, in the lead chambers. The present high price of the Sicilian sulphur is a great encouragement to its extraction from pyrites. It is said that the common English brimstone, such as was extracted from the copper pyrites of the Parys mine of Anglesey, contained fully a fifteenth of residuum, insoluble in boiling oil of turpentine, which was chiefly orpiment; while the fine Sicilian sulphur, now imported in vast quantities by the manufacturers of oil of vitriol, contains not more than 3 per cent. of foreign matter, chiefly earthy, but not at all arsenical.

Sulphur has been known from the most remote antiquity. From its kindling at a moderate temperature, it is employed for readily procuring fire, and lighting by its flame other bodies not so combustible. At Paris, the preparation of sulphur matches constitutes a considerable branch of industry. The sulphurous acid formed by the combustion of sulphur in the atmospheric air, is employed to bleach woollen and silken goods, as also cotton stockings; to disinfect vitiated air, though it is inferior in power to nitric acid vapour and chlorine; to kill mites, moths, and other destructive insects in collections of zoology; and to counteract too rapid fermentation in wine-vats, &c. As the same acid gas has the property of suddenly extinguishing flame, sulphur has been thrown into a chimney on fire, with the best effect; a handful of it being sometimes sufficient. Sulphur is also employed for cementing iron bars in stone; for taking impressions from seals and cameos, for which purpose it is kept previously melted for some time, to give the casts an appearance of bronze. Its principal uses, however, are for the manufactures of vermillion, or cinnabar, gunpowder, and sulphuric acid.

See METALLURGY, page 823, for the description of Gahn’s furnace for extracting sulphur from pyrites.

Pyrites as a bi-sulphuret, consisting of 45·5 parts of iron, and 54·5 of sulphur, may, by proper chemical means, be made to give off one half of its sulphur, or about 27 per cent.; but great care must be taken not to generate sulphurous acid, as is done very wastefully by the Fahlun and the Goslar processes. By the latter, indeed, not more than 1 or 2 parts of sulphur are obtained, by roasting 100 parts of the pyritous ores of the Rammelsberg mines. In these cases, the sulphur is burned, instead of being sublimed. The residuum of the operation, when it is well conducted, is black sulphuret of iron, which may be profitably employed for making copperas. The apparatus for extracting sulphur from pyrites should admit no more air than is barely necessary to promote the sublimation.--Sicily produced last year 70,000 tons of sulphur, and Tuscany 1200; of which Great Britain consumed 46,000; France, 18,000; other places, 6000. In 1820, Great Britain consumed only 5000 tons.

SULPHURATION, is the process by which woollen, silk, and cotton goods are exposed to the vapours of burning sulphur, or to sulphurous acid gas. In the article STRAW-HAT MANUFACTURE, I have described a simple and cheap apparatus, well adapted to this operation.

Sulphuring-rooms are sometimes constructed upon a great scale, in which blankets, shawls, and woollen clothes may be suspended freely upon poles or cords. The floor should be flagged with a sloping pavement, to favour the drainage of the water that drops down from the moistened cloth. The iron or stoneware vessels, in which the sulphur is burned, are set in the corners of the apartment. They should be increased in number according to the dimensions of the place, and distributed uniformly over it. The windows and the entrance door must be made to shut hermetically close. In the lower part of the door, there should be a small opening, with a sliding shutter, which may be raised or lowered by the mechanism of a cord passing over a pulley.

The aperture by which the sulphurous acid and azotic gases are let off, in order to carry on the combustion, should be somewhat larger than the opening at the bottom. A lofty chimney carries the noxious gases above the building, and diffuses them over a wide space, their ascension being promoted by means of a draught-pipe of iron, connected with an ordinary stove, provided with a valve to close its orifice when not kindled.

When the chamber is to be used, the goods are hung up, and a small fire is made in the draught-stove. The proper quantity of sulphur being next put into the shallow pans, it is kindled, the entrance door is closed, as well as its shutter, while a vent-hole near the ground is opened by drawing its cord, which passes over a pulley. After a few minutes, when the sulphur is fully kindled, that vent-hole must be almost entirely shut, by relaxing the cord; when the whole apparatus is to be let alone for a sufficient time.

The object of the preceding precautions is to prevent the sulphurous acid gas escaping from the chamber by the seams of the principal doorway. This is secured by closing it imperfectly, so that it may admit of the passage of somewhat more air than can enter by the upper seams, and the smallest quantity of fresh air that can support the combustion. The velocity of the current of air may be increased at pleasure, by enlarging the under vent-hole a little, and quickening the fire of the draught-stove.

Before opening the entrance door of the apartment, for the discharge of the goods, a small fire must be lighted in the draught furnace, the vent-hole must be thrown entirely open, and the sliding shutter of the door must be slid up, gradually more and more every quarter of an hour, and finally left wide open for a proper time. By this means the air of the chamber will become soon respirable.

SULPHURETTED HYDROGEN, is a gas, composed of one part of hydrogen and sixteen parts of sulphur, by weight. Its specific gravity is 1·1912, compared to air = 1·0000. It is the active constituent of the sulphureous mineral waters. When breathed, it is very deleterious to animal life; and being nearly twice as dense as air, it may be poured from its generating bottle into cavities; a scheme successfully employed by M. Thenard to destroy rats in their holes.

SULPHURIC ACID, _Vitriolic Acid_, or _Oil of Vitriol_ (_Acid sulfurique_, Fr.; _Schwefelsaüre_, Germ.). This important product, the agent of many chemical operations, was formerly procured by the distillation of dried sulphate of iron, called _green_ vitriol, whence the corrosive liquid which came over, having an oily consistence, was denominated oil of vitriol. This method has been superseded in Great Britain, France, and most other countries, by the combustion of sulphur along with nitre, in large leaden chambers; but as the former process, which is still practised at Bleyl in Bohemia, and Nordhausen in Saxony, gives birth to some interesting results, I shall describe it briefly.

Into a long horizontal furnace, or gallery of brickwork, a series of earthenware retorts, of a pear shape, is arranged, with curved necks fitted into stoneware bottles or condensers. Each retort is charged with sulphate of iron, which has been previously heated to moderate redness. The first product of the distillation, a slightly acidulous phlegm, is allowed to escape; then the retort and receiver are securely luted together. The fire is now raised, and urged briskly for 36 hours, whereby the strong sulphuric acid is expelled, in the form of heavy white vapours, which condense in the cold receiver into an oily-looking liquid. The latter portions, when received in a separate refrigerator, frequently concrete into a crystalline mass, formerly called glacial oil of vitriol. About 64 pounds of strong acid may be obtained from 600 pounds of copperas. It is brown-coloured; and varies in specific-gravity from 1·842 to 1·896. Its boiling point is so low as 120° Fahr. When re-distilled in a glass retort, into a receiver surrounded with ice, a very moderate heat sends over white fumes, which condense into a soft solid, in silky filaments, like asbestos, tough, and difficult to cut. When this is exposed to the air, it emits copious fumes of sulphuric (not sulphurous) acid. It burns holes in paper as rapidly as a red-hot iron. Dropped in small quantities into water, it excites a hissing noise, like ignited metal; and in larger quantities, it occasions an explosion. By dropping a fragment of it into a poised phial containing water, and stoppering instantly, to prevent the ejection of liquid, by the ebullition which always ensues, I got a dilute acid, containing a known portion of the solid acid, from the specific gravity of which, as well as from its saturating power, I ascertained that the above solid sulphuric acid was truly anhydrous (_void of water_), consisting of 1 equivalent proportion of sulphur, and 3 of oxygen; or, by weight, of 16 of the former, and 24 of the latter. This acid makes a red solution of indigo.

The production of sulphuric acid from sulphur and nitre may be elegantly illustrated by means of a glass globe with a stoppered hole at its side, and four bent glass tubes inserted into a leaden cap in its upper orifice. The first tube is to be connected with a heated matrass, disengaging sulphurous acid from copper filings and sulphuric acid; the second with a retort, disengaging more slowly deutoxide of azote (nitric oxide) from copper filings and nitric acid; the third with a vessel for furnishing steam in a moderate current towards the end of the process, when no water has been previously admitted into the balloon; the fourth tube may be upright, and terminate in a small funnel. Through the opening in the side of the globe, atmospherical air is to be admitted from time to time, by removing the stopper; after which, the residuary lighter azote may be allowed to escape by the funnel orifice.

The nitric oxide first absorbs oxygen from the air, becomes, in consequence, nitrous acid vapour, which giving up one third of its oxygen to the sulphurous acid, converts this, with the aid of water, into sulphuric acid, while itself returning to the state of nitric oxide, is again qualified to take oxygen from the air, and to transfer it to the sulphurous acid gas; and thus in perpetual rotation. These oxygenating and disoxygenating processes continue until nearly the whole oxygen of the atmospheric air contained in the globe is consumed. Were there little aqueous vapour present, those gases would soon cease to operate upon each other; for though the nitric oxide became nitrous acid, this would oxygenate little of the sulphurous acid, because the three substances would condense into white crystals upon the sides of the balloon, like hoar frost upon a window-pane in winter. These indicate a deficiency of aqueous vapour, and an excess of nitrous acid. On the admission of steam, the crystals disappear, the sulphuric acid is liquefied, the nitrous acid is converted into nitric acid and nitric oxide; the former of which combines with the water, while the latter is converted by the atmospheric oxygen into nitrous acid vapour. A certain quantity of water is therefore requisite to prevent the formation of that crystalline compound, which condenses the nitrous acid, and renders it inoperative in transforming fresh portions of sulphurous acid into sulphuric. On these principles alone is it possible to oxygenate the sulphurous acid, by the nitrous acid resuming and surrendering a dose of oxygen, in perpetual alternation.

It was MM. Clement and Desormes who first had the sagacity to trace these complicated changes. They showed that nitrous acid gas and sulphurous acid gas mixed, react on each other through the intervention of moisture; that there resulted thence a combination of sulphuric acid, deutoxide of azote (nitrous gas), and water; that this crystalline compound was instantly destroyed by more water, with the separation of the sulphuric acid in a liquid state, and the disengagement of nitrous gas; that this gas re-constituted nitrous acid at the expense of the atmospheric oxygen of the leaden chamber, and thus brought matters to their primary condition. From this point, starting again, the particles of sulphur in the sulphurous acid, through the agency of water, became fully oxygenated by the nitrous acid, and fell down in heavy drops of sulphuric acid, while the nitrous gas derived from the nitrous acid, had again recourse to the air for its lost dose of oxygen. This beautiful interchange of the oxygenous principle was found to go on, in their experiments, till either the sulphurous acid, or oxygen in the air, was exhausted.

They verified this proposition, with regard to what occurs in sulphuric acid chambers, by mixing in a crystal globe the three substances, deutoxide of azote, sulphurous acid, and atmospheric air. The immediate production of red vapours indicated the transformation of the deutoxide into nitrous acid gas; and now the introduction of a very little water caused the proper _reaction_, for opaque vapours rose, which deposited white star-form crystals on the surface of the glass. The gases were once more transparent and colourless; but another addition of water melted these crystals with effervescence, when ruddy vapours appeared. In this manner the phenomena were made to alternate, till the oxygen of the included air was expended, or all the sulphurous acid was converted into sulphuric. The residuary gases were found to be nitrous acid gas, and azote, without sulphurous acid gas; while unctuous sulphuric acid bedewed the inner surface of the globe. Hence, they justly concluded their new theory of the manufacture of oil of vitriol to be demonstrated.

In consequence of their discovery, the manufacture of this acid has received such improvements, that a nearly double product of it may now be obtained from the same weight of materials. Indeed, the economy may be reckoned to be much greater; for one half of the more costly ingredient, the nitre, formerly employed with a given weight of sulphur, suffices at present.

In the manufacture of sulphuric acid upon the great scale, two different systems of working were long prevalent; the intermittent or periodical, and the continuous or uniform. Both were carried on in large leaden chambers. In the former, the chambers were closed during the period of combustion and gaseous combination, but were opened from time to time to introduce fresh atmospheric air. This method is, I believe, generally abandoned now, on account of the difficulties and delays attending it, though it afforded large products in skilful hands. In the latter, a continuous current of air is allowed to enter at the oven in front of the chamber for the combustion of the sulphur, and there is a constant escape of nitrogen gas, with a little sulphurous acid gas, at the remote end of the roof.

_Fig._ 1101. represents a sulphuric acid chamber, _a_, _a_, are the brick or stone pillars upon which it rests; _b_, _b_, are the sustaining wooden beams or joists; _c_, is the chimney for the discharge of the nitrogen; _d_, is the roof, and _e_, the sole of the hearth for the combustion of the sulphur; _f_, is the cylindrical tunnel, or pipe of lead or cast iron, for conducting the gasiform materials into the chamber; _g_, is the steam-boiler; and _h_, the steam-pipe. That plan is variously modified, by different oil-of-vitriol makers in this country and in France. Very frequently, the oven _e_, _d_, is not situated under the chamber, but is built at the end of it, as at _i_, and arched over with brick, the crown being 9 inches thick. The pipe _f_, 18 inches in diameter, is then placed outside of the chamber, being inserted into a brick chimney, and, turning rectangularly, enters it opposite _k_. The sole of the hearth _e_, is a thick plate of cast iron (not hollowed as shown in the figure), 5 or 6 feet long, and 3 or 4 broad, with a small fireplace constructed beneath it, whose smoke-flue runs outwards, under the floor, to the side wall of the building. The oven is in this case about 2 feet in height, from the sole to the roof; and it has an iron door, about 12 inches by 15, which slides up and down in a tightly-fitted iron frame. This door is frequently placed in the side of the oven, parallel to the long side of the leaden chamber. A stout collar of lead is bolted to the chamber, where the pipe enters it. At the middle of the side of the chamber, about 2 feet above the ground, a leaden trough is fixed, which serves as a syphon-funnel and water-trap for introducing water to the acid gases.

Several manufacturers divide the chamber into a series of rectangular compartments, by parallel leaden screens, 10 or 12 feet asunder, and allow these compartments to communicate by a narrow opening, or a hole 1 foot square, in the top and bottom of each screen alternately. Thus the fumes, which enter from the chimney-pipe over _k_, will be forced, by the screen at _b_, to descend to 1, and pass through the opening there, to get into the second compartment, whence they will escape near the top at 2, thus circulating up and down, so as to occasion a complete agitation and intermixture of their heterogeneous particles. Into the side of the chamber, opposite to the centre of each compartment, a lead pipe enters, and proceeds towards the middle of the area, terminating in a narrow orifice, for discharging a jet of high-pressure steam from a boiler loaded with 40 pounds upon the square inch. This boiler should be placed under a shed exterior to the building. It deserves to be noted, that the incessant tremors produced in this pipe by the escape of the steam, cause the orifice to contract, and eventually to close almost entirely, just as the point of a glass tube does when exposed directly to the flame of a blowpipe. Provision should therefore be made against this event, by the chemical engineer.

Equidistant between the middle point and each end of the chamber, two round holes are cut out in its side, about 16 inches in diameter, and 2 feet from the floor; the sheet lead being folded back over the face of the strong deals which strengthen the chamber in that place. The edges of the holes are bevelled outwards, so as to fit a large conical plug of wood faced with lead, called a man-hole door. One or other of these doors is opened from time to time, to allow the superintendent to inspect the process, or workmen to enter, after the chamber is well ventilated, for the purpose of making repairs. The joists or tie-beams, that bind the rafters of the roof of both the leaden chamber and the house, must be at least 7 inches deep, by 3 broad, and of such length as to have their ends supported upon the outer wall, or the columnar supports of the roof, in case a number of chambers are enclosed together in parallel ranges under a vast shed. These beams, which lie two feet apart, suspend the leaden roof, by means of leaden straps, soldered to its upper surface and edges. The sides of the chamber are sustained by means of similar leaden straps affixed to the wooden posts (uprights), 4 inches broad by 3 thick, placed two or three feet apart along the sides of the chamber; resting on the ground below, and mortised into the tie-beams above. Some chambers rest upon a sand-floor; but they are preferably placed upon wooden joists, supported by pillars stretching over an open area, as shown in the figure, into which the workmen may descend readily, to examine the bottom.

The outlet _c_, on the top of the chamber, is sometimes joined to a long pipe of lead laid nearly horizontally, with a slight inclination upwards, along the roof, for favouring the condensation and return of acid matter.

At the extremity _l_, of the chamber, which, having a downward slope of 1 inch in every 20 feet, should stand from 3 to 6 inches (according to its length) lower than _i_, one leg of an inverted syphon pipe is fixed by fusion, into which the liquid of the chamber passing, will show by its altitude the depth on the bottom within. From the cup-shaped orifice of that bent-up pipe, the acid of the chamber is drawn off by an ordinary leaden syphon into the concentration pans.

The sheet lead of which the sides and top are made, should weigh from 5 to 6 pounds per square foot; that of the bottom should be nearly of double thickness.

Having now detailed, with sufficient minuteness, the construction of the chamber, I shall next describe the mode of operating with it. There are at least two plans at present in use for burning the sulphur continuously in the oven. In the one, the sulphur is laid on the hearth _e_, (or rather on the flat hearth in the separate oven, above described,) and is kindled by a slight fire placed under it; which fire, however, is allowed to go out after the first day, because the oven becomes by that time sufficiently heated by the sulphur flames to carry on the subsequent combustion. Upon the hearth, an iron tripod is set, supporting, a few inches above it, a hemispherical cast-iron bowl (basin) charged with nitre and its decomposing proportion of strong sulphuric acid. In the other plan, 12 parts of bruised sulphur, and 1 of nitre, are mixed in a leaden trough on the floor with 1 of strong sulphuric acid, and the mixture is shovelled through the sliding iron door upon the hot hearth. The successive charges of sulphur are proportioned, of course, to the size of the chamber. In one of the largest, which is 120 feet long, 20 broad, and 16 high, 12 cwt. are burned in the course of 24 hours, divided into 6 charges, every fourth hour, of 2 cwt. each. In chambers of one-sixth greater capacity, containing 1400 metres cube, 1 ton of sulphur is burned in 24 hours. This immense production was first introduced at Chaunay and Dieuze, under the management of M. Clement-Desormes. The bottom of the chamber should be covered at first with a thin stratum of sulphuric acid, of spec. grav. 1·07, which decomposes nitrous acid into oxygen and nitrous gas; but not with mere water, which would absorb the nitrous acid vapours, and withdraw them from their aerial sphere of action. The vapour of nitric acid, disengaged from the nitre on the hearth of the oven, when brought into intimate contact with the sulphurous acid, either gives up oxygen to it, becomes itself nitrous gas, and converts it into sulphuric acid; or combines with the sulphurous acid into the crystalline compound above described, which, the moment it meets with moisture, is decomposed into sulphuric acid and nitrous gas. The atmospherical oxygen of the chamber immediately reconverts this gas into nitrous or nitric acid fumes, which are again ready, with the co-operation of sulphurous acid gas and aqueous vapour, to produce fresh quantities of hydrous sulphuric acid (oil of vitriol) and nitrous gas. At low temperatures, this curious play of chemical affinities has a great tendency to form the crystalline compound, and to deposit it in a crust of considerable thickness (from one-half to one inch) on the sides of the chamber, so as to render the process inoperative. A circumstance of this kind occurred, in a very striking manner, during winter, in a manufacture of oil of vitriol in Russia; and it has sometimes occurred, to a moderate extent, in Scotland. It is called, at Marseilles, the _maladie des chambres_. It may be certainly prevented, by maintaining the interior of the chamber, by a jet of steam, at a temperature of 100° F. When these crystals fall into the dilute acid at the bottom, they are decomposed with a violent effervescence, and a hissing gurgling noise, somewhat like that of a tun of beer in brisk fermentation.

M. Clement-Desormes demonstrated the proposition relative to the influence of temperature by a decisive experiment. He took a glass globe, furnished with three tubulures, and put a bit of ice into it. Through the first opening he then introduced sulphurous acid gas; through the second, oxygen; and through the third, nitrous gas (deutoxide of azote). While the globe was kept cool, by being plunged in iced water, no sulphuric acid was formed, though all the ingredients essential to its production were present. But on exposing the globe to a temperature of 100° Fahr., the four bodies began immediately to react on each other, and oil of vitriol was condensed in visible _striæ_.

The introduction of steam is a modern invention, which has vastly facilitated and increased the production of oil of vitriol. It serves, by powerful agitation, not only to mix the different gaseous molecules intimately together, but to impel them against each other, and thus bring them within the sphere of their mutual chemical attraction. This is its mechanical effect. Its chemical agency is still more important. By supplying moisture at every point of the immense included space, it determines the formation of hydrous sulphuric acid, from the compound of nitric, nitrous, sulphurous, and dry sulphuric acids. No sooner is this reaction accomplished, than the nitrous gas resumes its oxygen, from the continuous atmospherical current, and becomes again fit to operate a like round of transmutations with sulphurous acid, steam, and oxygen. The nitrogen (azote), which ought to be the only residuum in a _perfectly_ regulated vitriol chamber, escapes, by its relative lightness, at the opening _c_, in the roof, or, more properly speaking, is displaced by the influx of the heavier gases at the entrance-pipe.

On the intermittent plan, after the consumption of each charge, and condensation of the product, the chamber was opened, and freely ventilated, so as to expel the residuary azote, and replenish it with fresh atmospheric air. In this system there were four distinct stages or periods:--1. Combustion for two hours; 2. Admission of steam, and settling, for an hour and a half; 3. Conversion, for three hours, during which interval the drops of strong acid were heard falling like heavy hailstones on the bottom; 4. Purging of the chamber, for three quarters of an hour.

By the continuous method, sulphuric acid may be currently obtained in the chambers, of the specific gravity 1·350, or 1·450 at most; for, when stronger, it absorbs and retains permanently much nitrous acid gas; but by the intermittent, so dense as 1·550, or even 1·620; whence in a district where fuel is high priced, as near Paris, this method recommended itself by economy in the concentration of the acid. In Great Britain, and even in most parts of France, however, where time, workmen’s wages, and interest of capital, are the paramount considerations, manufacturers do not find it for their interest in general to raise the density of the acid in the chambers above 1·400, or at most 1·500; as the further increase goes on at a retarded rate, and its concentration from 1·400 to 1·600, in leaden pans, costs very little.

At about the specific gravity of 1·35, in Great Britain, the liquid of the chambers is run off, by the syphon above described, into a leaden gutter or spout, which discharges it into a series of rectangular vessels made of large sheets of lead, of 12 or 14 lbs. to the square foot, simply folded up at the angles into pans 8 or 10 inches deep, resting upon a grate made of a pretty close row of wrought-iron bars of considerable strength, under which the flame of a furnace plays. Where coals are very cheap, each pan may have a separate fire; but where they are somewhat dear, the flame, after passing under the lowest pan of the range, which contains the strongest acid (at about 1·600), proceeds upwards with a slight slope to heat the pans of weaker acid, which, as it concentrates, is gradually run down by syphons to replenish the lower pans, in proportion as their aqueous matter is dissipated. The 3 or 4 pans constituting the range are thus placed in a straight line, but each at a different level, terrace-like; _en gradins_, as the French say.

When the acid has thereby acquired the density of 1·650, or 1·700 at most, it must be removed from the leaden evaporators, because, when of greater strength, it would begin to corrode them; and it is transferred into leaden coolers, or run through a long refrigeratory worm-pipe surrounded by cold water. In this state it is introduced into glass or platinum retorts, to undergo a final concentration, up to the specific gravity of 1·842, or even occasionally 1·845, in consequence of slight saline impurities. When glass retorts are used, they are set in a long sand-bath over a gallery furnace, resting on fire tiles, under which a powerful flame plays; and as the flue gradually ascends from the fireplace, near to which it is most distant from the tiles; to the remoter end, the heat acts with tolerable equality on the first and last retort in the range. When platinum stills are employed, they are fitted into the inside of cast-iron pots, which protect the thin bottom and sides of the precious metal. The fire being applied directly to the iron, causes a safe, rapid, and economical concentration of the acid. The iron pots, with their platinum interior, filled with concentrated boiling-hot oil of vitriol, are lifted out of the fire-seat by tackle, and let down into a cistern of cold water, to effect the speedy refrigeration of the acid, and facilitate its transvasion into carboys packed in osier baskets lined with straw. Sometimes, however, the acid is cooled by running it slowly off through a long platinum syphon, surrounded by another pipe filled with cold water. _Fig._ 1102. shows my contrivance for this purpose.

The under stopcock _a_, being shut, and the leg _b_, being plunged to nearly the bottom of the still, the worm is to be filled with concentrated cold acid through the funnel _c_. If that stopcock is now shut, and _a_ opened, the acid will flow out in such quantity as to rarefy the small portion of air in the upper part of the pipe _b_, sufficiently to make the hot acid rise up over the bend, and set the syphon in action. The flow of the fluid is to be so regulated by the stopcock _a_, that it may be greatly cooled in its passage by the surrounding cold water in the vessel _f_, which may be replenished by means of the tube and funnel _d_, and overflow at _e_.

A manufacturer of acid in Scotland, who burns in each chamber 210 pounds of sulphur in 24 hours, being at the rate of 420 pounds for 20,000 cubic feet (= nearly 2000 metres cube) has a product of nearly 3 pounds of concentrated oil of vitriol for every pound of sulphur and twelfth of a pound of nitre. The advantage of his process results, I conceive, from the lower concentration of the acid in the chambers, which favours its more rapid production.

The platinum retort admits of from 4 to 6 operations in a day, when it is well mounted and managed. It has a capital of platinum, furnished with a short neck, which conducts the disengaged vapours into a lead worm of condensation; and the liquid thus obtained is returned into the lead pans. Great care must be taken to prevent any particles of lead from getting into the platinum vessel, since at the temperature of boiling sulphuric acid, the lead unites with the precious metal, and thus causes holes in the retort. These must be repaired by soldering-on a plate of platinum with gold.

Before the separate oven or hearth for burning the sulphur in contact with the nitre was adopted, this combustible mixture was introduced into the chamber itself, spread on iron trays or earthen pans, supported above the water on iron stands. But this plan was very laborious and unproductive. It is no longer followed.

One of the characters of the good quality of sulphuric acid, is its dissolving indigo without altering its fine blue colour.

Sulphuric acid, when well prepared, is a colourless and inodorous liquid, of an oily aspect, possessing a specific gravity, in its most concentrated state, of 1·842, when redistilled, but as found in commerce, of 1·845. It is eminently acid and corrosive, so that a single drop will communicate the power of reddening litmus to a gallon of water, and will produce an ulcer of the skin when allowed to remain upon it. If swallowed in its strongest state, in even a small quantity, it acts so furiously on the throat and stomach as to cause intolerable agony and speedy death. Watery diluents, mixed with chalk or magnesia, are the readiest antidotes. At a temperature of about 600° F., or a few degrees below the melting point of lead, it boils and distils over like water. This is the best method of procuring sulphuric acid free from the saline and metallic matters with which it is sometimes contaminated.

The affinity of sulphuric acid for water is so strong that, when exposed in an open saucer, it imbibes one-third of its weight from the atmosphere in 24 hours, and fully six times its weight in a few months. Hence it should be kept excluded from the air. If four parts, by weight, of the strongest acid be suddenly mixed with one part of water, both being at 50° F., the temperature of the mixture will rise to 300°; while, on the other hand, if four parts of ice be mixed with one of sulphuric acid, they immediately liquefy and sink the thermometer to 4° below zero. From the great attraction existing between this acid and water, a saucer of it is employed to effect the rapid condensation of aqueous vapour as it exhales from a cup of water placed over it; both standing under the exhausted receiver of an air-pump. By the cold produced by this unchecked evaporation in vacuo, the water is speedily frozen.

To determine the purity of sulphuric acid, let it be slowly heated to the boiling point of water, and if any volatile acid matter be present, it will evaporate, with its characteristic smell. The presence of saline impurity, which is the common one, is discovered by evaporating a given weight of it in a small capsule of platinum placed on red-hot cinders. If more than two grains remain out of 500, the acid may be reckoned to be impure. The best test for sulphuric acid, and the soluble salts into which it enters, is the nitrate of baryta, of which 182 parts are equivalent to 49 of the strongest liquid acid, or to 40 of the dry, as it exists in crystallized sulphate of potassa. One twenty thousandth part of a grain of the acid may be detected by the grayish-white cloud which baryta forms with it. 100 parts of the concentrated acid are neutralized by 143 parts of dry carbonate of potassa, and by 110 of dry carbonate of soda, both perfectly pure.

Of all the acids, the sulphuric is most extensively used in the arts, and is, in fact, the primary agent for obtaining almost all the others, by disengaging them from their saline combinations. In this way, nitric, muriatic, tartaric, acetic, and many other acids, are procured. It is employed in the direct formation of alum, of the sulphates of copper, zinc, potassa, soda; in that of sulphuric ether, of sugar by the saccharification of starch, and in the preparation of phosphorus, &c. It serves also for opening the pores of skins in tanning, for clearing the surfaces of metals, for determining the nature of several salts by the acid characters that are disengaged, &c.

According to the analysis of Dr. Thomson, the crystalline compound deposited occasionally in the leaden chambers above described consists of--

Sulphurous acid 0·6387, or 3 atoms. Sulphuric acid 0·5290 2 Nitric acid 0·3450 1 atom. Water 0·0733 1 Sulphate of lead 0·0140.

He admits that the proportion of water is a little uncertain; and that the presence of sulphurous acid was not proved by direct analysis. When heated with water, the crystalline matter disengages nitrous gas in abundance; lets fall some sulphate of lead; and the liquid is found to be sulphuric acid. When heated without water, it is decomposed with emission of nitrous gas and fuming nitric acid; leaving a liquid which, mixed with water, produces a brisk effervescence, consisting chiefly of nitrous gas.

The following TABLE shows the quantity of concentrated and dry sulphuric acid in 100 parts of dilute, at different densities, by my experiments, published in the Quarterly Journal of Science, for October, 1817:--

+-------+---------+-------+ |Liquid.|Sp. grav.| Dry. | +-------+---------+-------+ | 100 | 1·8460 |81·54 | | 99 | 1·8438 |80·72 | | 98 | 1·8415 |79·90 | | 97 | 1·8391 |79·09 | | 96 | 1·8366 |78·28 | | 95 | 1·8340 |77·46 | | 94 | 1·8288 |76·65 | | 93 | 1·8235 |75·83 | | 92 | 1·8181 |75·02 | | 91 | 1·8026 |74·20 | | 90 | 1·8070 |73·39 | | 89 | 1·7986 |72·57 | | 88 | 1·7901 |71·75 | | 87 | 1·7815 |70·94 | | 86 | 1·7728 |70·12 | | 85 | 1·7640 |69·31 | | 84 | 1·7540 |68·49 | | 83 | 1·7425 |67·68 | | 82 | 1·7315 |66·86 | | 81 | 1·7200 |66·05 | | 80 | 1·7080 |65·23 | | 79 | 1·6972 |64·42 | | 78 | 1·6860 |63·60 | | 77 | 1·6744 |62·78 | | 76 | 1·6624 |61·97 | | 75 | 1·6500 |61·15 | | 74 | 1·6415 |60·34 | | 73 | 1·6321 |59·52 | | 72 | 1·6204 |58·71 | | 71 | 1·6090 |57·89 | | 70 | 1·5975 |57·08 | | 69 | 1·5868 |56·26 | | 68 | 1·5760 |55·45 | | 67 | 1·5648 |54·63 | | 66 | 1·5503 |53·82 | | 65 | 1·5390 |53·00 | | 64 | 1·5280 |52·18 | | 63 | 1·5170 |51·37 | | 62 | 1·5066 |50·55 | | 61 | 1·4960 |49·74 | | 60 | 1·4860 |48·92 | | 59 | 1·4760 |48·11 | | 58 | 1·4660 |47·29 | | 57 | 1·4560 |46·48 | | 56 | 1·4460 |45·66 | | 55 | 1·4360 |44·85 | | 54 | 1·4265 |44·03 | | 53 | 1·4170 |43·22 | | 52 | 1·4073 |42·40 | | 51 | 1·3977 |41·58 | | 50 | 1·3884 |40·77 | | 49 | 1·3788 |39·95 | | 48 | 1·3697 |39·14 | | 47 | 1·3612 |38·32 | | 46 | 1·3530 |37·51 | | 45 | 1·3440 |36·69 | | 44 | 1·3345 |35·88 | | 43 | 1·3255 |35·06 | | 42 | 1·3165 |34·25 | | 41 | 1·3080 |33·43 | | 40 | 1·2999 |32·61 | | 39 | 1·2913 |31·80 | | 38 | 1·2826 |30·98 | | 37 | 1·2740 |30·17 | | 36 | 1·2654 |29·35 | | 35 | 1·2572 |28·54 | | 34 | 1·2490 |27·72 | | 33 | 1·2409 |26·91 | | 32 | 1·2334 |26·09 | | 31 | 1·2260 |25·28 | | 30 | 1·2184 |24·46 | | 29 | 1·2108 |23·65 | | 28 | 1·2032 |22·83 | | 27 | 1·1956 |22·01 | | 26 | 1·1876 |21·20 | | 25 | 1·1792 |20·38 | | 24 | 1·1706 |19·57 | | 23 | 1·1626 |18·75 | | 22 | 1·1549 |17·94 | | 21 | 1·1480 |17·12 | | 20 | 1·1410 |16·31 | | 19 | 1·1330 |15·49 | | 18 | 1·1246 |14·68 | | 17 | 1·1165 |13·86 | | 16 | 1·1090 |13·05 | | 15 | 1·1019 |12·23 | | 14 | 1·0953 |11·41 | | 13 | 1·0887 |10·60 | | 12 | 1·0809 | 9·78 | | 11 | 1·0743 | 8·97 | | 10 | 1·0682 | 8·15 | | 9 | 1·0614 | 7·34 | | 8 | 1·0544 | 6·52 | | 7 | 1·0477 | 5·71 | | 6 | 1·0405 | 4·89 | | 5 | 1·0336 | 4·08 | | 4 | 1·0268 | 3·26 | | 3 | 1·0206 | 2·446 | | 2 | 1·0140 | 1·63 | | 1 | 1·0074 | 0·8154| +-------+---------+-------+

SUMACH (Eng. and Fr.; _Schmack_, Germ.); is the powder of the leaves, peduncles, and young branches of the _Rhus coriaria_, and _Rhus cotinus_, shrubs which grow in Hungary, the Bannat, and the Illyrian provinces. Both kinds contain tannin, with a little yellow colouring-matter, and are a good deal employed for tanning light-coloured leathers; but the first is the best. With mordants, it dyes nearly the same colours as galls. In calico-printing, sumach affords, with a mordant of tin, a yellow colour; with acetate of iron, weak or strong, a gray or black; and with sulphate of zinc, a brownish-yellow. A decoction of sumach reddens litmus paper strongly; gives white flocks with the protomuriate of tin; pale-yellow flocks with alum; blue flocks with red sulphate of iron, with an abundant precipitate. In the south of France, the twigs and leaves of the _Coriaria myrthifolia_ are used for dyeing, under the name of _rédoul_, or _rodou_.

SWEEP-WASHER, is the person who extracts from the sweepings, potsherds, &c., of refineries of silver and gold, the small residuum of precious metal.

SYNTHESIS, is a Greek word, which signifies combination, and is applied to the chemical action which unites dissimilar bodies into a uniform compound; as sulphuric acid and lime, into gypsum; or chlorine and sodium, into culinary salt.

SYRUP, is a solution of sugar in water. Cane-juice, concentrated to a density of 1·300, forms a syrup which does not ferment in the transport home from the West Indies, and may be boiled and refined at one step into superior sugar-loaves, with eminent advantage to the planter, the refiner, and the revenue.

T.

TABBYING, or WATERING, is the process of giving stuffs a wavy appearance with the calender.

TACAMAHAC, is a resin obtained from the _Fagura octandra_, a tree which grows in Mexico and the West Indies. It occurs in yellowish pieces, of a strong smell, and a bitterish aromatic taste. That from the island of Madagascar has a greenish tint.

TAFFETY, is a light silk fabric, with a considerable lustre or gloss.

TAFIA, is a variety of rum.

TALC, is a mineral genus, which is divided into two species, the common and the indurated. The first occurs massive, disseminated in plates, imitative, or crystallized in small six-sided tables. It is splendent, pearly, or semi-metallic, translucent, flexible, but not elastic. It yields to the nail; spec. gray. 2·77. Before the blowpipe, it first whitens, and then fuses into an enamel globule. It consists of--silica, 62; magnesia, 27; alumina, 1·5; oxide of iron, 3·5; water, 6. Klaproth found 2-1/2 per cent. of potash in it. It is found in beds of clay-slate and mica-slate, in Aberdeenshire, Banffshire, Perthshire, Salzburg, the Tyrol, and St. Gothard. It is an ingredient in rouge for the toilette, communicating softness to the skin. It gives the flesh polish to soft alabaster figures, and is also used in porcelain paste.

The second species, or talc-slate, has a greenish-gray colour; is massive, with tabular fragments, translucent on the edges, soft, with a white streak; easily cut or broken, but is not flexible; and has a greasy feel. It occurs in the same localities as the preceding. It is employed in the porcelain and crayon manufactures; as also as a crayon itself, by carpenters, tailors, and glaziers.

TALLOW (_Suif_, Fr.; _Talg_, Germ.); is the concrete fat of quadrupeds and man. That of the ox consists of 76 parts of stearine, and 24 of oleine; that of the sheep contains somewhat more stearine. See FAT and STEARINE.

Tallow imported into the United Kingdom, in 1836, 1,186,364 cwts. 1 qr. 4 lbs.; in 1837, 1,308,734 cwts. 1 qr. 4 lbs. Retained for home consumption, in 1836, 1,318,678 cwts. 1 qr. 25 lbs.; in 1837, 1,294,009 cwts. 2 qrs. 21 lbs. Duty received, in 1836, _£_208,284; in 1837, _£_204,377.

TALLOW, PINEY. See PINEY TALLOW.

TAMPING, is a term used by miners to express the filling up of the hole which they have bored in a rock, for the purpose of blasting it with gunpowder. See MINES.

TAN, or TANNIC ACID. (_Tannin_, Fr.; _Gerbstoff_, Germ.) See its preparation and properties described under GALLS.

The barks replete with this principle should be stripped with hatchets and bills, from the trunk and branches of trees, not less than 30 years of age, in spring, when their sap flows most freely. Trees are also sometimes barked in autumn, and left standing, whereby they cease to vegetate, and perish ere long; but afford, it is thought, a more compact timber. This operation is, however, too troublesome to be generally practised, and therefore the bark is commonly obtained from felled trees; and it is richer in tannin the older they are. The bark mill is described in Gregory’s _Mechanics_, and other similar works.

The following TABLE shows the quantity of extractive matter and tan in 100 parts of the several substances:--

+----------------------------------+--------+----------+-------------+ | Substances. |In 480, |In about |In 100 parts,| | |by Davy.|8 oz., by |by Cadet de | | | |Biggins. |Gassincourt. | +----------------------------------+--------+----------+-------------+ |White inner bark of old oak | 72 | | 21 | | Do. young oak | 77 | | | | Do. Spanish chestnut | 63 | 30 | | | Do. Leicester willow | 79 | | | |Coloured or middle bark of oak | 19 | | | | Do. Spanish chestnut | 14 | | | | Do. Leicester willow | 16 | | | |Entire bark of oak | 29 | | | | Do. Spanish chestnut | 21 | | | | Do. Leicester willow | 33 | 109 | | | Do. Elm | 13 | 28 | | | Do. Common willow | 11 |boughs, 31| | |Sicilian sumach | 78 | 158 | | |Malaga sumach | 79 | | | |Souchong tea | 48 | | | |Green tea | 41 | | | |Bombay catechu | 261 | | | |Bengal catechu | 231 | | | |Nut-galls | 127 | | 46 | |Bark of oak, cut in winter | -- | 30 | | | Do. beech | -- | 31 | | | Do. Elder | -- | 41 | | | Do. Plum-tree | -- | 58 | | |Bark of the trunk of Willow | -- | 52 | | | Do. Sycamore | -- | 53 | 16 | |Bark of Birch | -- | 54 | | |Bark of Cherry-tree | -- | 59 | 24 | | Do. Sallow | -- | 59 | | | Do. Poplar | -- | 76 | | | Do. Hazel | -- | 79 | | | Do. Ash | -- | 82 | | | Do. trunk of Span. chestnut | -- | 98 | | | Do. Smooth oak | -- | 104 | | | Do. Oak, cut in spring | -- | 108 | | |Root of Tormentil | -- | | 46 | |Cornus sanguinea of Canada | -- | | 44 | |Bark of Alder | -- | | 36 | | Do. Apricot | -- | | 32 | | Do. Pomegranate | -- | | 32 | | Do. Cornish cherry-tree | -- | | 19 | | Do. Weeping willow | -- | | 16 | | Do. Bohemian olive | -- | | 14 | | Do. Tan shrub with myrtle leaves| -- | | 13 | | Do. Virginian sumach | -- | | 10 | | Do. Green oak | -- | | 10 | | Do. Service-tree | -- | | 8 | | Do. Rose chestnut of Amer. | -- | | 8 | | Do. Rose chestnut | -- | | 6 | | Do. Rose chestnut of Carolina | -- | | 6 | | Do. Sumach of Carolina | -- | | 5 | +----------------------------------+--------+----------+-------------+

TANNING (_Tanner_, Fr.; _Gärberei_, Germ.); is the art of converting skin into LEATHER, which see. It has been ascertained, beyond a doubt, that “the saturated infusions of astringent barks contain much less extractive matter, in proportion to their tannin, than the weak infusions; and when skin is quickly tanned (in the former), common experience shows that it produces leather less durable than leather slowly formed.”[66] The older tanners, who prided themselves on producing a substantial article, were so much impressed with the advantages of slowly impregnating skin with astringent matter, that they employed no concentrated infusion (ooze) in their pits, but stratified the skins with abundance of ground bark, and covered them with soft water, knowing that its active principles are very soluble, and that, by being gradually extracted, they would penetrate uniformly the whole of the animal fibres, instead of acting chiefly upon the surface, and making brittle leather, as the strong infusions never fail to do. In fact, 100 pounds of skin, quickly tanned in a strong infusion of bark, produce 137 of leather; while 100 pounds, slowly tanned in a weak infusion, produce only 117-1/2. The additional 19-1/2 pounds weight in the former case serve merely to swell the tanner’s bill, while they deteriorate his leather, and cause it to contain much less of the textile animal solid. Leather thus highly charged with tannin, is, moreover, so spongy as to allow moisture to pass readily through its pores, to the great discomfort and danger of persons who wear shoes made of it. That the saving of time, and the increase of product, are temptations strong enough to induce many modern tanners to steep their skins in a succession of strong infusions of bark, is sufficiently intelligible; but that any shoemaker should be so ignorant or so foolish as to proclaim that his leather is made by a process so injurious to its quality, is unaccountably stupid.

[66] Sir H. Davy, on the Operation of Astringent Vegetables in Tanning.--_Phil. Trans._ 1803.

TANTALUM, is the rare metal; also called COLUMBIUM.

TAPESTRY, is an ornamental figured textile fabric of worsted or silk, for lining the walls of apartments; of which the most famous is that of the Gobelins Royal Manufactory, near Paris.

TAPIOCA, is a modification of starch, partially converted into gum, by heating and stirring cassava upon iron plates. See CASSAVA and STARCH.

TAR (_Goudron_, Fr.; _Ther_, Germ.); is the viscid, brown-black, resino-oleaginous compound, obtained by distilling wood in close vessels, or in ovens of a peculiar construction. See CHARCOAL, PITCOAL, COKING OF, and PYROLIGNOUS ACID. According to Reichenbach, tar contains the peculiar proximate principles, _paraffine_, _eupion_, _creosote_, _picamar_, _pittacal_, besides pyrogenous resin, or _pyretine_, pyrogenous oil, or _pyroleine_, and vinegar. The resin, oil, and vinegar are called empyreumatic, in common language.

Tar imported into the United Kingdom, in 1836, 9,797 lsts. 8 brls.; in 1837, 11,480 lsts. 1 brl. Retained for home consumption, in 1836, 9,639 lsts. 8 brls.; in 1837, 11,686 lsts. 8 brls. Duty received, in 1836, _£_7,231; in 1837, _£_8,775.

TARRAS; see CEMENT, and MORTAR, HYDRAULIC.

TARTAR (_Tartre_, Fr.; _Weinstein_, Germ.); called also argal or argol; is the crude bitartrate of potassa, which exists in the juice of the grape, and is deposited from wines in their fermenting casks, being precipitated in proportion as the alcohol is formed, in consequence of its insolubility in that liquid. There are two sorts of argal known in commerce, the white, and the red; the former, which is of a pale-pinkish colour, is the crust let fall by white wines; the latter is a dark-red, from red wines.

The crude tartar is purified, or converted into cream of tartar, at Montpellier, by the following process:--

The argal having been ground under vertical mill-stones, and sifted, one part of it is boiled with 15 of water, in conical copper kettles, tinned on the inside. As soon as it is dissolved, 3-1/2 parts of ground pipe-clay are introduced. The solution being well stirred, and then settled, is drawn off into crystallizing vessels, to cool; the crystals found concreted on the sides and bottom are picked out, washed with water, and dried. The mother-water is employed upon a fresh portion of argal. The crystals of the first crop are re-dissolved, re-crystallized, and exposed upon stretched canvas to the sun and air, to be bleached. The clay serves to abstract the colouring-matter. The crystals formed upon the surface are the whitest, whence the name cream of tartar is derived.

Purified tartar, the bitartrate of potassa, is thus obtained in hard clusters of small colourless crystals, which, examined by a lens, are seen to be transparent 4-sided prisms. It has no smell, but a feebly acid taste; is unchangeable in the air, has a specific gravity of 1·953, dissolves in 16 parts of boiling water, and in 200 parts at 60° F. It is insoluble in alcohol. It consists of 24·956 potassa, 70·276 tartaric acid, and 4·768 water. It affords, by dry distillation, pyrotartaric acid, and an empyreumatic oil; while carbonate of potassa remains associated with much charcoal in the retort, constituting black flux. Tartar is used in dyeing, medicine, and for extracting--

TARTARIC ACID. (_Acide tartarique_, Fr.; _Weinsteinsäure_, Germ.) This is prepared by adding gradually to a boiling-hot solution of 100 parts of tartar, in a large copper boiler, 26 of chalk, made into a smooth pap with water. A brisk effervescence ensues, by the disengagement of the carbonic acid of the chalk, while its base combines with the acid excess in the tartar, and forms an insoluble precipitate of tartrate of lime. The supernatant liquor, which is a solution of neutral tartrate of potassa, must be drawn off by a syphon, and decomposed by a solution of chloride of calcium (muriate of lime). 28-1/2 parts of the dry chloride are sufficient for 100 of tartar. The tartrate of lime, from both processes, is to be washed with water, drained, and then subjected, in a leaden cistern, to the action of 49 parts of sulphuric acid, previously diluted with 8 times its weight of water: 100 of dry tartrate take 75 of oil of vitriol. This mixture, after digestion for a few days, is converted into sulphate of lime and tartaric acid. The latter is to be separated from the former by decantation, filtration through canvas, and edulcoration of the sulphate of lime upon the filter.

The clear acid is to be concentrated in leaden pans, by a moderate heat, till it acquires the density of 40° B. (spec. grav. 1·38), and then it is run off, clear from any sediment, into leaden or stoneware vessels, which are set in a dry stove-room for it to crystallize. The crystals, being re-dissolved and re-crystallized, become colourless 6-sided prisms. In decomposing the tartrate of lime, a very slight excess of sulphuric acid must be employed; because pure tartaric acid would dissolve any tartrate of lime that may escape decomposition. Bone black, previously freed from its carbonate and phosphate of lime, by muriatic acid, is sometimes employed to blanch the coloured solutions of the first crystals. Tartaric acid contains nearly 9 per cent. of combined water. It is soluble in two parts of water at 60°, and in its own weight of boiling water. In its dry state, as it exists in the tartrate of lime or lead, it consists of 36·8 of carbon, 3 of hydrogen, and 60·2 of oxygen. It is much employed in calico-printing, and for making sodaic powders.

TARTRATES, are salts composed of tartaric acid, and oxidized bases, in equivalent proportions.

TAWING, is the process of preparing the white skins of the sheep doe, &c. See LEATHER.

TEA, _green_, contains 34·6 parts of tannin, 5·9 of gum, 5·7 of vegetable albumine, 51·3 of ligneous fibre, with 2·5 of loss; and _black_ tea contains 40·6 of tannin, 6·3 of gum, 6·4 of vegetable albumine, 44·8 of ligneous fibre, with 2 of loss. The ashes contain silica, carbonate of lime, magnesia, and chloride of potassium.--_Frank._ Davy obtained 32·5 of extract from Souchong tea; of which 10 were precipitated by gelatine. He found 8·5 only of tannin in green tea. The latter chemist is most to be depended upon. Chemical analysis has not yet discovered that principle in tea, to which its exciting property is due.

_The Chinese method of making Black Tea in Upper Assam._[67]--In the first place, the youngest and most tender leaves are gathered; but when there are many hands and a great quantity of leaves to be collected, the people employed nip off with the forefinger and thumb the fine end of the branch with about four leaves on, and sometimes even more, if they look tender. These are all brought to the place where they are to be converted into tea; they are then put into a large, circular, open-worked bamboo basket, having a rim all round, two fingers broad. The leaves are thinly scattered in these baskets, and then placed in a framework of bamboo, in all appearance like the side of an Indian hut without grass, resting on posts, 2 feet from the ground, with an angle of about 25°. The baskets with leaves are put in this frame to dry in the sun, and are pushed up and brought down by a long bamboo with a circular piece of wood at the end. The leaves are permitted to dry about two hours, being occasionally turned; but the time required for this process depends on the heat of the sun. When they begin to have a slightly withered appearance, they are taken down and brought into the house, where they are placed on a frame to cool for half an hour. They are then put into smaller baskets of the same kind as the former, and placed on a stand. People are now employed to soften the leaves still more, by gently clapping them between their hands, with their fingers and thumb extended, and tossing them up and letting them fall, for about five or ten minutes. They are then again put on the frame during half an hour, and brought down and clapped with the hands as before. This is done three successive times, until the leaves become to the touch like soft leather; the beating and putting away being said to give the tea the black colour and bitter flavour. After this the tea is put into hot cast-iron pans, which are fixed in a circular mud fireplace, so that the flame cannot ascend round the pan to incommode the operator. This pan is well heated by a straw or bamboo fire to a certain degree. About two pounds of the leaves are then put into each hot pan, and spread in such a manner that all the leaves may get the same degree of heat. They are every now and then briskly turned with the naked hand, to prevent a leaf from being burnt. When the leaves become inconveniently hot to the hand, they are quickly taken out and delivered to another man with a close-worked bamboo basket ready to receive them. A few leaves that may have been left behind are smartly brushed out with a bamboo broom; all this time a brisk fire is kept up under the pan. After the pan has been used in this manner three or four times, a bucket of cold water is thrown in, and a soft brickbat and bamboo broom used, to give it a good scouring out; the water is thrown out of the pan by the brush on one side, the pan itself being never taken off. The leaves, all hot on the bamboo basket, are laid on a table that has a narrow rim on its back, to prevent these baskets from slipping off when pushed against it. The two pounds of hot leaves are now divided into two or three parcels, and distributed to as many men, who stand up to the table with the leaves right before them, and each placing his legs close together; the leaves are next collected into a ball, which he gently grasps in his left hand, with the thumb extended, the fingers close together, and the hand resting on the little finger. The right hand must be extended in the same manner as the left, but with the palm turned downwards, resting on the top of the ball of tea leaves. Both hands are now employed to roll and propel the ball along; the left hand pushing it on, and allowing it to revolve as it moves; the right hand also pushes it forward, resting on it with some force, and keeping it down to express the juice which the leaves contain. The art lies here in giving the ball a circular motion, and permitting it to turn under and in the hand two or three whole revolutions, before the arms are extended to their full length, and drawing the ball of leaves quickly back without leaving a leaf behind, being rolled for about five minutes in this way. The ball of tea leaves is from time to time gently and delicately opened with the fingers, lifted as high as the face, and then allowed to fall again. This is done two or three times, to separate the leaves; and afterwards the basket with the leaves is lifted up as often, and receives a circular shake to bring these towards the centre. The leaves are now taken back to the hot pans, and spread out in them as before, being again turned with the naked hand, and when hot taken out and rolled; after which they are put into the drying basket, and spread on a sieve which is in the centre of the basket, and the whole placed over a charcoal fire. The fire is very nicely regulated; there must not be the least smoke, and the charcoal should be well picked.

[67] By C. A. Bruce, superintendent of tea culture.

When the fire is lighted, it is fanned until it gets a fine red glare, and the smoke is all gone off; being every now and then stirred and the coals brought into the centre, so as to leave the outer edge low. When the leaves are put into the drying basket, they are gently separated by lifting them up with the fingers of both hands extended far apart, and allowing them to fall down again; they are placed 3 or 4 inches deep on the sieve, leaving a passage in the centre for the hot air to pass. Before it is put over the fire, the drying basket receives a smart slap with both hands in the act of lifting it up, which is done to shake down any leaves that might otherwise drop through the sieve, or to prevent them from falling into the fire and occasioning a smoke, which would affect and spoil the tea. This slap on the basket is invariably applied throughout the stages of the tea manufacture. There is always a large basket underneath to receive the small leaves that fall, which are afterwards collected, dried, and added to the other tea; in no case are the baskets or sieves permitted to touch or remain on the ground, but always laid on a receiver with three legs. After the leaves have been half dried in the drying basket, and while they are still soft, they are taken off the fire and put into large open-worked baskets, and then put on the shelf, in order that the tea may improve in colour.

Next day the leaves are all sorted into large, middling, and small; sometimes there are four sorts. All these, the Chinese informed me, become so many different kinds of teas; the smallest leaves they called Pha-ho, the second Pow-chong, the third Su-chong, and the fourth, or the largest leaves, Toy-chong. After this assortment they are again put on the sieve in the drying basket (taking great care not to mix the sorts), and on the fire, as on the preceding day; but now very little more than will cover the bottom of the sieve is put in at one time, the same care of the fire is taken as before, and the same precaution of tapping the drying basket every now and then. The tea is taken off the fire with the nicest care, for fear of any particle of the tea falling into it. Whenever the drying basket is taken off, it is put on the receiver, the sieve in the drying basket taken out, the tea turned over, the sieve replaced, the tap given, and the basket placed again over the fire. As the tea becomes crisp, it is taken out and thrown into a large receiving basket, until all the quantity on hand has become alike dried and crisp; from which basket it is again removed into the drying basket, but now in much larger quantities. It is then piled up eight and ten inches high on the sieve in the drying basket; in the centre a small passage is left for the hot air to ascend; the fire that was before bright and clear, has now ashes thrown on it to deaden its effect, and the shakings that have been collected are put on the top of all; the tap is given, and the basket with the greatest care is put over the fire. Another basket is placed over the whole, to throw back any heat that may ascend. Now and then it is taken off, and put on the receiver; the hands, with the fingers wide apart, are run down the sides of the basket to the sieve, and the tea gently turned over, the passage in the centre again made, &c., and the basket again placed on the fire. It is from time to time examined, and when the leaves have become so crisp that they break by the slightest pressure of the fingers, it is taken off, when the tea is ready. All the different kinds of leaves underwent the same operation. The tea is now little by little put into boxes, and first pressed down with the hands and then with the feet (clean stockings having been previously put on).

There is a small room inside of the tea-house, 7 cubits square and 5 high, having bamboos laid across on the top to support a net work of bamboo, and the sides of the room smeared with mud to exclude the air. When there is wet weather, and the leaves cannot be dried in the sun, they are laid out on the top of this room, on the network, on an iron pan, the same as is used to heat the leaves; some fire is put into it, either of grass or bamboo, so that the flame may ascend high; the pan is put on a square wooden frame, that has wooden rollers on its legs, and pushed round and round this little room by one man, while another feeds the fire, the leaves on the top being occasionally turned; when they are a little withered, the fire is taken away, and the leaves brought down and manufactured into tea, in the same manner as if it had been dried in the sun. But this is not a good plan, and never had recourse to, if it can possibly be avoided.

Tea imported into the United Kingdom, in 1836, 49,307,701 lbs.; in 1837, 36,765,735 lbs. Retained for home consumption, in 1836, 49,841,507 lbs.; in 1837, 31,872 lbs. Duty received, in 1836, _£_4,728,600; in 1837, _£_3,319,665.

TEASEL, the head of the thistle (_Dipsacus_), is employed to raise the nap of cloth. See WOOLLEN MANUFACTURE.

TEETH. See BONES.

TELLURIUM, is a metal, too rare and high-priced to be used in the arts.

TERRA-COTTA, literally baked clay, is the name given to statues, architectural decorations, figures, vases, &c., modelled or cast in a paste made of pipe or potter’s clay and a fine-grained colourless sand, from Ryegate, with pulverized potsherds, slowly dried in the air, and afterwards fired to a stony hardness in a proper kiln. See STONE, ARTIFICIAL.

TERRA DI SIENA, is a brown ferruginous ochre, employed in painting.

TESTS, are chemical reagents of any kind, which indicate, by special characters, the nature of any substance, simple or compound. See ASSAY, the several metals, acids, &c.

TEXTILE FABRICS. The first business of the weaver is to adapt those parts of his loom which move the warp, to the formation of the various kinds of ornamental figures which the cloth is intended to exhibit. This subject is called the _draught_, drawing or reading in, and the cording of looms. In every species of weaving, whether direct or cross, the whole difference of pattern or effect is produced, either by the succession in which the threads of warp are introduced into the heddles, or by the succession in which those heddles are moved in the working. The heddles being stretched between two shafts of wood, all the heddles connected by the same shafts are called a leaf; and as the operation of introducing the warp into any number of leaves is called drawing a warp, the plan of succession is called the draught. When this operation has been performed correctly, the next part of the weaver’s business is to connect the different leaves with the levers or treddles by which they are to be moved, so that one or more may be raised or sunk by every treddle successively, as may be required to produce the peculiar pattern. These connections being made by coupling the different parts of the apparatus by cords, this operation is called the cording. In order to direct the operator in this part of his business, especially if previously unacquainted with the particular pattern upon which he is employed, plans are drawn upon paper, specimens of which will be found in _figs._ 1103, 1104., &c. These plans are horizontal sections of a loom, the heddles being represented across the paper at _a_, and the treddles under them, and crossing them at right angles, at _b_. In _figs._ 1103. and 1104. they are represented as if they were distinct pieces of wood, those across being the under shaft of each leaf of heddles, and those at the left hand the treddles. See WEAVING. In actual weaving, the treddles are placed at right angles to the heddles, the sinking cords descending perpendicularly as nearly as possible to the centre of the latter. Placing them at the left hand, therefore, is only for ready inspection, and for practical convenience. At _c_ a few threads of warp are shown as they pass through the heddles, and the thick lines denote the leaf with which each thread is connected. Thus, in _fig._ 1103., the right-hand thread, next to _a_, passes through the eye of a heddle upon the back leaf, and is disconnected with all the other leaves; the next thread passes through a heddle on the second leaf; the third, through the third leaf; the fourth, through the fourth leaf; and the fifth, through the fifth or front leaf. One set of the draught being now completed, the weaver recommences with the back leaf, and proceeds in the same succession again to the front. Two sets of the draught are represented in this figure, and the same succession, it is understood by weavers (who seldom draw more than one set), must be repeated until all the warp is included. When they proceed to apply the cords, the right-hand part of the plan at _b_ serves as a guide. In all the plans shown by these figures, excepting one which shall be noticed, a connexion must be formed, by cording, between every leaf of heddles and every treddle; for all the leaves must either rise or sink. The raising motion is effected by coupling the leaf to one end of its correspondent top lever; the other end of this lever is tied to the long march below, and this to the treddle. The sinking connexion is carried directly from under the leaf to the treddle. To direct a weaver which of these connexions is to be formed with each treddle, a black spot is placed when a leaf is to be raised, where the leaf and treddle intersect each other upon the plan, and the sinking connexions are left blank. For example, to cord, the treddle 1, to the back leaf, put a raising cord, and to each of the other four, sinking cords; for the treddle 2, raise the second leaf, and sink the remaining four, and so of the rest; the spot always denoting the leaf or leaves to be raised. The _figs._ 1103. and 1104. are drawn for the purpose of rendering the general principle of this kind of plans familiar to those who have not been previously acquainted with them; but those who have been accustomed to manufacture and weave ornamented cloths, never consume time by representing either heddles or treddles as solid or distinct bodies. They content themselves with ruling a number of lines across a piece of paper, sufficient to make the intervals between these lines represent the number of leaves required. Upon these intervals, they merely mark the succession of the draught, without producing every line to resemble a thread of warp. At the left hand, they draw as many lines across the former as will afford an interval for each treddle; and in the squares produced by the intersections of these lines, they place the dots, spots, or ciphers which denote the raising cords. It is also common to continue the cross lines which denote the treddle a considerable length beyond the intersections, and to mark by dots, placed diagonally in the intervals, the order or succession in which the treddles are to be pressed down in weaving. The former of these modes has been adopted in the remaining _figs._ to 1112.; but to save room, the latter has been avoided, and the succession marked by the order of the figures under the intervals which denote the treddles.

Some explanation of the various kinds of fanciful cloths represented by these plans, may serve further to illustrate this subject, which is, perhaps, the most important of any connected with the manufacture of cloth, and will also enable a person who thoroughly studies them, readily to acquire a competent knowledge of the other varieties in weaving, which are boundless. _Figs._ 1103. and 1104. represent the draught and cording of the two varieties of tweeled cloth wrought with five leaves of heddles. The first is the regular or run tweel, which, as every leaf rises in regular succession, while the rest are sunk, interweaves the warp and woof only at every fifth interval, and as the succession is uniform, the cloth when woven, presents the appearance of parallel diagonal lines, at an angle of about 45° over the whole surface. A tweel may have the regularity of its diagonal lines broken by applying the cording as in _fig._ 1104. It will be observed, that in both figures the draught of the warp is precisely the same, and that the whole difference of the two plans consists in the order of placing the spots denoting the raising cords, the first being regular and successive, and the second alternate.

_Figs._ 1105. and 1106. are the regular and broken tweels which may be produced with eight leaves. This properly is the tweel denominated satin in the silk manufacture, although many webs of silk wrought with only five leaves receive that appellation. Some of the finest Florentine silks are tweeled with sixteen leaves. When the broken tweel of eight leaves is used, the effect is much superior to what could be produced by a smaller number; for in this, two leaves are passed in every interval, which gives a much nearer resemblance to plain cloth than the others. For this reason it is preferred in weaving the finest damasks. The draught of the eight-leaf tweel differs in nothing from the others, excepting in the number of leaves. The difference of the cording in the broken tweel, will appear by inspecting the cyphers which mark the raising cords, and comparing them with those of the broken tweel of five leaves. _Fig._ 1107. represents the draught and cording of striped dimity of a tweel of five leaves. This is the most simple species of fanciful tweeling. It consists of ten leaves, or double the number of the common tweel. These ten leaves are moved by only five treddles, in the same manner as a common tweel. The stripe is formed by one set, of the leaves flushing the warp, and the other set, the woof. The figure represents a stripe formed by ten threads, alternately drawn through each of the two sets of leaves. In this case, the stripe and the intervals will be equally broad, and what is the stripe upon one side of the cloth, will be the interval upon the other, and _vice versâ_. But great variety of patterns may be introduced by drawing the warp in greater or smaller portions through either set. The tweel is of the regular kind, but may be broken by placing the cording as in _fig._ 1104. It will be observed that the cording-marks of the lower or front leaves are exactly the converse of the other set; for where a raising mark is placed upon one, it is marked for sinking in the other; that is to say, the mark is omitted; and all leaves which sink in the one, are marked for raising in the other: thus, one thread rises in succession in the back set, and four sink; but in the front set, four rise, and only one sinks. The woof, of course, passing over the four sunk threads, and under the raised one, in the first instance, is flushed above; but where the reverse takes place, as in the second, it is flushed below; and thus the appearance of a stripe is formed. The analogy subsisting between striped dimity and dornock, is so great, that before noticing the plan for fancy dimity, it may be proper to allude to the dornock, the plan of which is represented by _fig._ 1108.

The draught of dornock is precisely the same in every respect with that of striped dimity. It also consists of two sets of tweeling-heddles, whether three, four, or five leaves are used for each set. The right-hand set of treddles is also corded exactly in the same way, as will appear by comparing them. But as the dimity is a continued stripe from the beginning to the end of the web, only five treddles are required to move ten leaves. The dornock being checker-work, the weaver must possess the power of reversing this at pleasure. He therefore adds five more treddles, the cording of which is exactly the reverse of the former; that is to say, the back leaves, in the former case, having one leaf raised, and four sunk, have, by working with these additional treddles, one leaf sunk and four leaves raised. The front leaves are in the same manner reversed, and the mounting is complete. So long as the weaver continues to work with either set, a stripe will be formed, as in the dimity; but when he changes his feet from one set to the other, the whole effect is reversed, and the checkers formed. The dornock pattern upon the design-paper, _fig._ 1108., may be thus explained: let every square of the design represent five threads upon either set of the heddles, which are said by weavers to be once over the draught, supposing the tweel to be one of five leaves; draw three parallel lines, as under, to form two intervals, each representing one of the sets; the draught will then be as follows:--

+-------------------------------+ | 4 1 4 1 1 4 1 | +-------------------------------+ | 4 4 1 1 1 4 4 | +-------------------------------+

The above is exactly so much of the pattern as is there laid down, to show its appearance; but one whole range of the pattern is completed by the figure 1, nearest to the right hand upon the lower interval between the lines, and the remaining figures, nearer to the right, form the beginning of a second range or set. These are to be repeated in the same way across the whole warp. The lower interval represents the five front leaves; the upper interval, the five back ones. The first figure 4, denotes that five threads are to be successively drawn upon the back leaves, and this operation repeated four times. The first figure 4, in the lower interval, expresses that the same is to be done upon the front leaves; and each figure, by its diagonal position, shows how often, and in what succession, five threads are to be drawn upon the leaves which the interval in which it is placed represents.

Dornocks of more extensive patterns are sometimes woven with 3, 4, 5, and even 6 sets of leaves; but after the leaves exceed 15 in number, they both occupy an inconvenient space, and are very unwieldy to work. For these reasons the diaper harness is in almost every instance preferred.

_Fig._ 1109. represents the draught and cording of a fanciful species of dimity, in which it will be observed that the warp is not drawn directly from the back to the front leaf, as in the former examples; but when it has arrived at either external leaf, the draught is reversed, and returns gradually to the other. The same draught is frequently used in tweeling, when it is wished that the diagonal lines should appear upon the cloth in a zigzag direction. This plan exhibits the draught and cording which will produce the pattern upon the design-paper in _fig._ 1103. _a_. Were all the squares produced by the intersection of the lines denoting the leaves and treddles, where the raised dots are placed, filled the same as on the design, they would produce the effect of exactly one-fourth of that pattern. This is caused by the reversing of the draught, which gives the other side reversed as on the design; and when all the treddles, from 1 to 16, have been successively used in the working, one-half of the pattern will become complete. The weaver then goes again over his treddles, in the reversed order of the numbers, from 17 to 30, when the other half of the pattern will be completed. From this similarity of the cording to the design, it is easy, when a design is given, to make out the draught and cording proper to work it; and when the cording is given, to see its effect upon the design.

_Fig._ 1110. represents the draught of the diaper mounting, and the cording of the front leaves, which are moved by treddles. From the plan, it will appear that 5 threads are included in every mail of the harness, and that these are drawn in single threads through the front leaves. The cording forms an exception to the general rules, that when one or more leaves are raised, all the rest must be sunk; for in this instance, one leaf rises, one sinks, and three remain stationary. An additional mark, therefore, is used in this plan. The dots, as formerly, denote raising cords; the blanks, sinking cords; and where the cord is to be totally omitted, the cross marks × are placed.

_Fig._ 1111. is the draught and cording of a spot whose two sides are similar, but reversed. That upon the plan forms a diamond, similar to the one drawn upon the design paper in the diagram, but smaller in size. The draught here is reversed, as in the dimity plan, and the treading is also to be reversed, after arriving at 6, to complete the diamond. Like it, too, the raising marks form one-fourth of the pattern. In weaving spots, they are commonly placed at intervals, with a portion of plain cloth between them, and in alternate rows, the spots of one row being between those of the other. But as intervals of plain cloth must take place, both by the warp and woof, 2 leaves are added for that purpose. The front, or ground leaf, includes every second thread of the whole warp; the second, or plain leaf, that part which forms the intervals by the warp. The remaining leaves form the spots; the first six being allotted to one row of spots, and the second six to the next row; where each spot is in the centre between the former. The reversed draught of the first is shown entire, and is succeeded by 12 threads of plain. One-half of the draught of the next row is then given, which is to be completed exactly like the first, and succeeded by 12 threads more of plain; when, one set of the pattern being finished, the same succession is to be repeated over the whole warp. As spots are formed by inserting woof of coarser dimensions than that which forms the fabric, every second thread only is allotted for the spotting. Those included in the front, or ground leaf, are represented by lines, and the spot threads between them, by marks in the intervals, as in the other plans.

The treddles necessary to work this spot are, in number, 14. Of these, the two in the centre, _a_, _b_, when pressed alternately, will produce plain cloth; for _b_ raises the front leaf, which includes half of the warp, and sinks all the rest; while _a_ exactly reverses the operation. The spot-treddles on the right hand work the row contained in the first six spot-leaves; and those upon the left hand, the row contained in the second six. In working spots, one thread, or shot of spotting-woof, and two of plain, are successively inserted, by means of two separate shuttles.

Dissimilar spots, are those whose sides are quite different from each other. The draught only of these is represented by _fig._ 1112. The cording depends entirely upon the figure.

_Fig._ 1113. represents any solid body composed of parts _lashed_ together. If the darkened squares be supposed to be beams of wood, connected by cordage, they will give a precise idea of textile fabric. The beams cannot come into actual contact, because, if the _lashing_ cords were as fine even as human hairs, they must still require space. The thickness is that of one beam and one cord; but if the cords touch each other, it may then be one beam and two cords; but it is not possible in practical weaving to bring every thread of weft into actual contact. It may therefore be assumed, that the thickness is equal to the diameter of one thread of the warp, added to that of one yarn of the weft; and when these are equal, the thickness of the cloth is double of that diameter. Denser cloth would not be sufficiently pliant or flexible.

_Fig._ 1114. is a representation of a section of cloth of an open fabric, where the round dots which represent the warp are placed at a considerable distance from each other.

_Fig._ 1115. may be supposed a plain fabric of that description which approaches the most nearly to any idea we can form of the most dense or close contact of which yarn can be made susceptible. Here the warp is supposed to be so tightly stretched in the loom as to retain entirely the parallel state, without any curvature, and the whole flexure is therefore given to the woof. This mode of weaving can never really exist; but if the warp be sufficiently strong to bear any tight stretching, and the woof be spun very soft and flexible, something very near it may be produced. This way of making cloth is well fitted for those goods which require to give considerable warmth; but they are sometimes the means of very gross fraud and imposition; for if the warp is made of very slender threads, and the woof of slackly twisted cotton or woollen yarn, where the fibrils of the stuff, being but slightly brought into contact, are rough and oozy, a great appearance of thickness and strength may be given to the eye, when the cloth is absolutely so flimsy, that it may be torn asunder as easily as a sheet of writing-paper. Many frauds of this kind are practised.

In _fig._ 1116. is given a representation of the position of a fabric of cloth in section, as it is in the loom before the warp has been closed upon the woof, which still appears as a straight line. This figure may usefully illustrate the direction and ratio of contraction which must unavoidably take place in every kind of cloth, according to the density of the texture, the dimensions of the threads, and the description of the cloth. Let A, B, represent one thread of woof completely stretched by the velocity of the shuttle in passing between the threads of warp which are represented by the round dots 1, 2, &c., and those distinguished by 8, 9, &c. When these threads are closed by the operation of the heddles to form the inner texture, the first tendency will be to move in the direction 1 _b_, 2 _b_, &c., for those above, and in that of 8 _a_, 9 _a_, &c., for those below; but the contraction for A, B, by its deviation from a straight to a curved line, in consequence of the compression of the warp threads 1 _b_, 2 _b_, &c., and 1 _a_, 2 _a_, &c., in closing, will produce, by the action of the two powers at right angles to each other, the oblique or diagonal direction denoted by the lines 1, 8-2, 9, to the left, for the threads above, and that expressed by the lines 2, 8-3, 9, &c., to the right, for the threads below. Now, as the whole deviation is produced by the flexure of the thread A, B, if A is supposed to be placed at the middle of the cloth, equidistant from the two extremities, or _selvages_ as they are called by weavers, the thread at 1 may be supposed to move really in the direction 1 _b_, and all the others to approach to it in the directions represented, whilst those to the right would approach in the same ratio, but the line of approximation would be inverted. _Fig._ 1117. represents that common fabric used for lawns, muslins, and the middle kind of goods, the excellence of which neither consists in the greatest strength, nor in the greatest transparency. It is entirely a medium between _fig._ 1114. and _fig._ 1115.

In the efforts to give great strength and thickness to cloth, it will be obvious that the common mode of weaving, by constant intersection of warp and woof, although it may be perhaps the best which can be devised for the former, presents invincible obstructions to the latter, beyond a certain limit. To remedy this, two modes of weaving are in common use, which, while they add to the power of compressing a great quantity of materials in a small compass, possess the additional advantage of affording much facility for adding ornament to the superficies of the fabric. The first of these is double cloth, or two webs woven together, and joined by the operation. This is chiefly used for carpets; and its geometrical principles are entirely the same as those of plain cloth, supposing the webs to be sewed together. A section of the cloth will be found in _fig._ 1118. See CARPET.

Of the simplest kind of tweeled fabrics, a section is given in _fig._ 1119.

The great and prominent advantage of the tweeled fabric, in point of texture, arises from the facility with which a very great quantity of materials may be put closely together. In the figure, the warp is represented by the dots in the same straight line as in the plain fabrics; but if we consider the direction and ratio of contraction, upon principles similar to those laid down in the explanation given of _fig._ 1116., we shall readily discover the very different way in which the tweeled fabric is affected.

When the dotted lines are drawn at _a_, _b_, _c_, _d_, their direction of contraction, instead of being upon every second or alternate thread, is only upon every fifth thread, and the natural tendency would consequently be, to bring the whole into the form represented by the lines and dotted circles at _a_, _b_, _c_, _d_. In point, then, of thickness, from the upper to the under superficies, it is evident that the whole fabric has increased in the ratio of nearly three to one. On the other hand, it will appear, that four threads or cylinders being thus put together in one solid mass, might be supposed only one thread, or like the strands of a rope before it is twisted; but, to remedy this, the thread being shifted every time, the whole forms a body in which much aggregate matter is compressed; but where, being less firmly united, the accession of strength acquired by the accumulation of materials is partially counteracted by the want of equal firmness of junction.

The second quality of the tweeled fabric, _susceptibility of receiving ornament_, arises from its capability of being inverted at pleasure, as in _fig._ 1120. In this figure we have, as before, four threads, and one alternately intersected; but here the four threads marked 1 and 2 are under the woof, while those marked 3 and 4 are above.

_Fig._ 1121. represents that kind of tweeled work which produces an ornamental effect, and adds even to the strength of a fabric, in so far as accumulation of matter can be considered in that light. The figure represents a piece of velvet cut in section, and of that kind which, being woven upon a tweeled ground, is known by the name of Genoa velvet. 1st. Because, by combining a great quantity of material in a small compass, they afford great warmth. 2nd. From the great resistance which they oppose to external friction, they are very durable. And, 3rd. Because, from the very nature of the texture, they afford the finest means of rich ornamental decoration.

The use of velvet cloths in cold weather is a sufficient proof of the truth of the first. The manufacture of plush, corduroy, and other stuffs for the dress of those exposed to the accidents of laborious employment, evinces the second; and the ornamented velvets and Wilton carpeting, are demonstrative of the third of these positions.

In the figure, the diagonal form which both the warp and woof of cloth assume, is very apparent from the smallness of the scale. Besides what this adds to the strength of the cloth, the flushed part, which appears interwoven at the darkly shaded intervals 1, 2, &c., forms, when finished, the whole covering or upper surface. The principle, in so far as regards texture, is entirely the same as any other tweeled fabric.

_Fig._ 1122., which represents corduroy, or king’s cord, is merely striped velvet. The principle is the same, and the figure shows that the one is a copy of the other. The remaining figures represent those kinds of work which are of the most flimsy and open description of texture; those in which neither strength, warmth, nor durability are much required, and of which openness and transparency are the chief recommendations.

_Fig._ 1123. represents common gauze, or _linau_, a substance very much used for various purposes. The essential difference between this description of cloth and all others, consists in the warp being turned or twisted like a rope during the operation of weaving, and hence it bears a considerable analogy to _lace_. The twining of gauze is not continued in the same direction, but is alternately from right to left, and _vice versâ_, between every intersection of the woof. The fabric of gauze is always open, flimsy, and transparent; but, from the turning of the warp, it possesses an uncommon degree of strength and tenacity in proportion to the quantity of material which it contains. This quality, together with the transparency of the fabric, renders it peculiarly adapted for ornamental purposes of various kinds, particularly for flowering or figuring, either in the loom; or by the needle. In the warp of gauze; there arises a much greater degree of contraction during the weaving, than in any other species of cloth; and this is produced by the turning. The twisting between every intersection of weft amounts precisely to one complete revolution of both threads; hence this difference exists between this and every other species of weaving, namely, that the one thread of warp is always above the woof, and the contiguous thread is always below.

_Fig._ 1124. represents a section of another species of twisted cloth, which is known by the name of catgut, and which differs from the gauze only, by being subjected to a greater degree of twine in weaving; for in place of one revolution between each intersection, a revolution and a half is always given; and thus the warp is alternately above and below, as in other kinds of weaving.

_Fig._ 1125. is a superficial representation of the most simple kind of ornamental network produced in the loom. It is called a whip-net by weavers, who use the term whip for any substance interwoven in cloth for ornamental purposes, when it is distinct from the ground of the fabric. In this, the difference is merely in the crossing of the warp; for it is very evident that the crossings at 1, 2, 3, 4, and 5, are of different threads from those at 6, 7, 8, and 9.

_Fig._ 1126. represents, superficially, what is called the mail-net, and is merely a combination of common gauze and the whip-net in the same fabric. The gauze here being in the same direction as the dotted line in the former figure, the whole fabric is evidently a continued succession of right-angled triangles, of which the woof forms the basis, the gauze part the perpendiculars, and the whip part the hypothenuses. The contraction here being very different, it is necessary that the gauze and whip parts should be stretched upon separate beams.

In order to design ornamental figures upon cloths, the lines which are drawn from the top to the bottom of the paper may be supposed to represent the warp; and those drawn across, the woof of the web; any number of threads being supposed to be included between every two lines. The paper thus forms a double scale, by which, in the first instance, the size and form of the pattern may be determined with great precision; and the whole subsequent operations of the weaver regulated, both in mounting and working his loom. To enable the projector of a new pattern to judge properly of its effects, when transferred from the paper to the cloth, it will be essentially necessary that he should bear constantly in his view the comparative scale of magnitude which the design will bear in each, regulating his ideas always by square or superficial measurement. Thus, in the large design, _fig._ 1127., representing a bird perched upon the branch of a tree, it will be proper, in the first place, to count the number of spaces from the point of the bill to the extremity of the tail; and to render this the more easy, it is to be observed that every tenth line is drawn considerably bolder than the others. This number in the design is 135 spaces. Counting again, from the stem of the branch to the upper part of the bird’s head, he will find 76 spaces. Between these spaces, therefore, the whole superficial measure of the pattern is contained. By the measure of the paper, this may be easily tried with a pair of compasses, and will be found to be nearly 6-5/10 inches in length, by 3-3/16 inches in breadth. Now, if this is to be woven in a reed containing 800 intervals in 37 inches, and if every interval contains five threads, supposed to be contained between every two parallel lines, the length will be 6·24 inches, and the breadth 3·52 inches nearly; so that the figure upon the cloth would be very nearly of the same dimensions as that upon the paper; but if a 1200 reed were used, instead of an 800, the dimensions would be proportionally contracted.

A correct idea being formed of the design, the weaver may proceed to mount his loom according to the pattern; and this is done by two persons, one of whom takes from the design the instructions necessary for the other to follow in tying his cords.

_Fig._ 1128. is a representation of the most simple species of table-linen, which is merely an imitation of checker-work of various sizes; and is known in Scotland, where the manufacture is chiefly practised, by the name of Dornock. When a pattern is formed upon tweeled cloth, by reversing the flushing, the two sides of the fabric being dissimilar, one may be supposed to be represented by the black marks, and the other by the part of the figure which is left uncoloured. For such a pattern as this, two sets of common tweel-heddles, moved in the ordinary way, by a double succession of heddles, are sufficient. The other part of _fig._ 1128. is a design of that intermediate kind of ornamental work which is called diaper, and which partakes partly of the nature of the dornock, and partly of that of the damask and tapestry. The principle upon which all these descriptions of goods are woven is entirely the same, and the only difference is in the extent of the design, and the means by which it is executed. _Fig._ 1129. is a design for a border of a handkerchief or napkin, which may be executed either in the manner of damask, or as the spotting is practised in the lighter fabrics.

THENARD’S BLUE, or COBALT BLUE, is prepared by digesting the oxide of cobalt used in the potteries, with nitric acid, evaporating the nitrate almost to dryness, diluting it with water, and filtering, to separate some arseniate of iron, which usually precipitates. The clear liquor is to be poured into a solution of phosphate of soda, whence an insoluble phosphate of cobalt falls. This being well washed, is to be intimately mixed in its soft state with eight times its weight of well-washed gelatinous alumina, which has been obtained by pouring a solution of alum into water of ammonia in excess. The uniformly coloured paste is to be spread upon plates, dried in a stove, then bruised dry in a mortar, enclosed in a crucible, and subjected to a cherry-red heat for half an hour. On taking out the crucible, and letting it cool, the fine blue pigment is to be removed into a bottle, which is to be stoppered till used.

The arseniate of cobalt may be substituted, in the above process, for the phosphate, but it must be mixed with sixteen times its weight of the washed gelatinous alumina. The arseniate is procured by pouring the dilute nitrate of cobalt into a solution of arseniate of potassa. If nitrate of cobalt be mixed with the alumina, and the mixture be treated as above described, a blue pigment will also be obtained, but paler than the preceding, showing that the colour consists essentially of alumina stained with oxide of cobalt.

THERMOMETER, signifies the measure of heat. Its description belongs to a treatise on chemical physics.

THERMOSTAT, is the name of an apparatus for regulating temperature, in vaporization, distillation, heating baths or hothouses, arid ventilating apartments, &c.; for which I obtained a patent in the year 1831. It operates upon the physical principle, that when two thin metallic bars of different expansibilities are riveted or soldered facewise together, any change of temperature in them will cause a sensible movement of flexure in the compound bar, to one side or other; which movement may be made to operate, by the intervention of levers, &c., in any desired degree, upon valves, stopcocks, stove-registers, air-ventilators, &c.; so as to regulate the temperature of the media in which the said compound bars are placed. Two long rulers, one of steel, and one of hard hammered brass, riveted together, answer very well; the object being not simply to _indicate_, but to _control_ or _modify_ temperature. The following diagrams will illustrate a few out of the numerous applications of this instrument:--

_Fig._ 1130. _a_, _b_, is a single thermostatic bar, consisting of two or more bars or rulers of differently expansible solids (of which, in certain cases, wood may be one): these bars or rulers are firmly riveted or soldered together, face to face. One end of the compound bar is fixed by bolts at _a_, to the interior of the containing cistern, boiler, or apartment, _a_, _l_, _m_, _b_, whereof the temperature has to be regulated, and the other end of the compound bar at _b_, is left free to move down towards _c_, by the flexure which will take place when its temperature is raised.

The end _b_, is connected by a link, _b_, _d_, with a lever _d_, _e_, which is moved by the flexure into the dotted position _b_, _g_, causing the turning-valve, air-ventilator, or register, _o_, _n_, to revolve with a corresponding angular motion, whereby the lever will raise the equipoised slide-damper _k_, _i_, which is suspended by a link from the end _e_, of the lever _e_, _d_, into the position _k_, _h_. Thus a hothouse or a water-bath may have its temperature regulated by the contemporaneous admission of warm, and discharge of cold air, or water.

_Fig._ 1131. _a_, _b_, _c_, is a thermostatic hoop, immersed horizontally beneath the surface of the water-bath of a still. The hoop is fixed at _a_, and the two ends _b_, _c_, are connected by two links _b d_, _c d_, with a straight sliding rod _d_, _h_, to which the hoop will give an endwise motion, when its temperature is altered; _e_; is an adjusting screw-nut on the rod _d_, _h_, for setting the lever _f_, _g_, which is fixed on the axis of the turning-valve or cock _f_; at any desired position, so that the valve may be opened or shut at any desired temperature, corresponding to the widening of the points _b_, _c_, and the consentaneous retraction of the point _d_, towards the circumference _a_, _b_, _c_, of the hoop. _g_, _h_, is an arc graduated by a thermometer, after the screw-piece _e_ has been adjusted. Through a hole at _h_, the guide-rod passes. _i_, is the cold-water cistern; _i_, _f_, _k_, the pipe to admit cold water; _l_, the overflow pipe, at which the excess of hot water runs off.

_Fig._ 1132. shows a pair of thermostatic bars, bolted fast together at the ends _a_. The free ends _b_, _c_, are of unequal length, so as to act by the cross links _d_, _f_, on the stopcock _e_. The links are jointed to the handle of the turning plug of the cock, on opposite sides of its centre; whereby that plug will be turned round in proportion to the widening of the points _b_, _c_. _h_, _g_, is the pipe communicating with the stopcock.

Suppose that for certain purposes in pharmacy, dyeing, or any other chemical art, a water-bath is required to be maintained steadily at a temperature of 150° F.: let the combined thermostatic bars, hinged together at _e_, _f_, _fig._ 1133., be placed in the bath, between the outer and inner vessels _a_, _b_, _c_, _d_, being bolted fast to the inner vessel at _g_; and have their sliding rod _k_, connected by a link with a lever fixed upon the turning plug of the stopcock _i_, which introduces cold water from a cistern _m_, through a pipe _m_, _i_, _n_, into the bottom part of the bath. The length of the link must be so adjusted that the flexure of the bars, when they are at a temperature of 150°, will open the said stopcock, and admit cold water to pass into the bottom of the bath through the pipe _i_, _n_, whereby hot water will be displaced at the top of the bath through an open overflow-pipe at _q_. An oil bath may be regulated on the same plan; the hot oil overflowing from _q_, into a refrigeratory worm, from which it may be restored to the cistern _m_. When a water bath is heated by the distribution of a tortuous steam pipe through it, as _i_, _n_, _o_, _p_, it will be necessary to connect the link of the thermostatic bars with the lever of the turning plug of the steam-cock, or of the throttle valve _i_, in order that the bars, by their flexure, may shut or open the steam passage more or less, according as the temperature of the water in the bath shall tend more or less to deviate from the pitch to which the apparatus has been adjusted. The water of the condensed steam will pass off from the sloping winding-pipe _i_, _n_, _o_, _p_, through the sloping orifice _p_. A saline, acid, or alkaline bath has a boiling temperature proportional to its degree of concentration, and may therefore have its heat regulated by immersing a thermostat in it, and connecting the working part of the instrument with a stopcock _i_, which will admit water to dilute the bath whenever by evaporation it has become concentrated, and has acquired a higher boiling point. The space for the bath, between the outer and inner pans, should communicate by one pipe with the water-cistern _m_; and by another pipe, with a safety cistern _r_, into which the bath may be allowed to overflow during any sudden excess of ebullition.

_Fig._ 1136. is a thermostatic apparatus, composed of three pairs of bars _d_, _d_, _d_, which are represented in a state of flexure by heat; but they become nearly straight and parallel when cold, _a_, _b_, _c_, is a guide rod, fixed at one end by an adjusting screw _e_, in the strong frame _f_, _e_, having deep guide grooves at the sides. _f_, _g_, is the working-rod, which moves endways when the bars _d_, _d_, _d_, operate by heat or cold. A square register-plate _h_, _g_, may be affixed to the rod _f_, _g_, so as to be moved backwards and forwards thereby, according to the variations of temperature; or the rod _f_, _g_, may cause the circular turning air-register _i_, to revolve by rack and wheel-work, or by a chain and pulley. The register-plate _h_, _g_, or turning register _i_, is situated at the ceiling or upper part of the chamber, and serves to let out hot air. _k_, is a pulley, over which a cord runs to raise or lower a hot-air register _l_, which may be situated near the floor of the apartment or hothouse, to admit hot air into the room. _c_, is a milled head, for adjusting the thermostat, by means of the screw at _e_, in order that it may regulate the temperature to any degree.

_Fig._ 1137. represents a chimney, furnished with a _pyrostat_ _a_, _b_, _c_, acting by the links _b_, _d_, _e_, _c_, on a damper _f_, _h_, _g_. The more expansible metal is in the present example supposed to be on the outside. The plane of the damper-plate will, in this case, be turned more directly into the passage of the draught through the chimney by increase of temperature.

_Fig._ 1135. represents a circular turning register, such as is used for a stove, or stove-grate, or for ventilating apartments; it is furnished with a series of spiral thermostatic bars, each bar being fixed fast at the circumference of the circle _b_, _c_, of the fixed plate of the air-register; and all the bars act in concert at the centre _a_, of the twining part of the register, by their ends being inserted between the teeth of a small pinion, or by being jointed to the central part of the turning plate by small pins.

_Fig._ 1134. represents another arrangement of my thermostatic apparatus applied to a circular turning register, like the preceding, for ventilating apartments. Two pairs of compound bars are applied so as to act in concert, by means of the links _a c_, _b c_, on the opposite ends of a short lever, which is fixed on the central part of the turning plate of the air-register. The two pairs of compound bars _a_, _b_, are fastened to the circumference of the fixed plate of the turning register, by two sliding rods _a d_, _b e_, which are furnished with adjusting screws. Their motion or flexure is transmitted by the links _a c_, and _b c_, to the turning plate, about its centre, for the purpose of shutting or opening the ventilating sectorial apertures, more or less, according to the temperature of the air which surrounds the thermostatic turning register. By adjusting the screws _a d_, and _b c_, the turning register is made to close all its apertures at any desired degree of temperature; but whenever the air is above that temperature, the flexure of the compound bars will open the apertures.

THIMBLE (_Dé à coudre_, Fr.; _Fingerhut_ (_fingerhat_), Germ.); is a small truncated metallic cone, deviating little from a cylinder, smooth within, and symmetrically pitted on the outside with numerous rows of indentations, which is put upon the tip of the middle finger of the right hand, to enable it to push the needle readily and safely through cloth or leather, in the act of sewing. This little instrument is fashioned in two ways; either with a pitted round end, or without one; the latter, called the open thimble, being employed by tailors, upholsterers, and, generally speaking, by _needle-men_. The following ingenious process for making this essential implement, the contrivance of M. M. Rouy and Berthier, of Paris, has been much celebrated, and very successful. Sheet-iron, one twenty-fourth of an inch thick, is cut into strips, of dimensions suited to the intended size of the thimbles. These strips are passed under a punch-press, whereby they are cut into discs of about 2 inches diameter, tagged together by a tail. Each strip contains one dozen of these blanks. A child is employed to make them red-hot, and to lay them on a mandril nicely fitted to their size. The workman now strikes the middle of each with a round-faced punch, about the thickness of his finger, and thus sinks it into the concavity of the first mandril. He then transfers it successively to another mandril, which has five hollows of successively increasing depth; and, by striking it into them, brings it to the proper shape.

A second workman takes this rude thimble, sticks it in the chuck of his lathe, in order to polish it within, then turns it outside, marks the circles for the gold ornament, and indents the pits most cleverly with a kind of milling tool. The thimbles are next annealed, brightened, and gilt inside, with a very thin cone of gold leaf, which is firmly united to the surface of the iron, simply by the strong pressure of a smooth steel mandril. A gold fillet is applied to the outside, in an annular space turned to receive it, being fixed, by pressure at the edges, into a minute groove formed on the lathe.

Thimbles are made in this country by means of moulds in the stamping-machine. See STAMPING OF METALS.

THORINA, is a primitive earth, with a metallic basis, discovered in 1828, by Berzelius. It was extracted from the mineral _thorite_, of which it constitutes 58 per cent., and where it is associated with the oxides of iron, lead, manganese, tin, and uranium, besides earths and alkalis, in all 12 substances. Pure thorina is a white powder, without taste, smell, or alkaline reaction on litmus. When dried and calcined, it is not affected by either the nitric or muriatic acid. It may be fused with borax into a transparent glass, but not with potash or soda. Fresh precipitated thorina is a hydrate, which dissolves readily in the above acids, as well as in solutions of the carbonates of potash, soda, and ammonia, but not in these alkalis in a pure state. This earth consists of 74·5 parts of the metal _thorinum_, combined with 100 of oxygen. Its hydrate contains one equivalent prime of water. It is hitherto merely a chemical curiosity, remarkable chiefly for a density of 9·402, far greater than that of all the earths, and even of copper.

THREAD MANUFACTURE. The doubling and twisting of cotton or linen yarn into a compact thread, for weaving bobbin-net, or for sewing garments, is performed by a machine resembling the throstle of the cotton-spinner. _Fig._ 1138. shows the thread-frame in a transverse section, perpendicular to its length. _a_, is the strong framing of cast iron; _b_, is the _creel_, or shelf, in which the bobbins of yarn _l_, _l_, are set loosely upon their respective skewers, along the whole line of the machine, their lower ends turning in oiled steps, and their upper in wire eyes; _c_, is a glass rod, across which the yarn runs as it is unwound; _d_, _d_, are oblong narrow troughs, lined with lead, and filled with water, for moistening the thread during its torsion; the threads being made to pass through eyes at the bottom of the fork _e_, which has an upright stem for lifting it out, without wetting the fingers, when any thing goes amiss; _f_, _f_, are the pressing rollers, the under one _g_, being of smooth iron, and the upper one _h_, of box-wood; the former extends from end to end of the frame, in lengths comprehending 18 threads, which are joined by square pieces, as in the drawing-rollers of the mule-jenny. The necks of the under rollers are supported, at the ends and the middle, by the standards _i_, secured to square bases _j_, both made of cast iron. The upper cylinder has an iron axis, and is formed of as many rollers as there are threads; each roller being kept in its place upon the lower one by the guides _k_, whose vertical slots receive the ends of the axes.

The yarn delivered by the bobbin _l_, glides over the rod _c_, and descends into the trough _d_, _e_, where it gets wetted; on emerging, it goes along the bottom of the roller _g_, turns up, so as to pass between it and _h_, then turns round the top of _h_, and finally proceeds obliquely downwards, to be wound upon the bobbin _m_, after traversing the guide-eye _n_. These guides are fixed to the end of a plate, which may be turned up by a hinge-joint at _o_, to make room for the bobbins to be changed.

There are three distinct simultaneous movements to be considered in this machine: 1. that of the rollers, or rather of the under roller, for the upper one revolves merely by friction; 2. that of the spindles _m_, _s´_; 3. the up-and-down motion of the bobbins upon the spindles.

The first of these motions is produced by means of toothed wheels, upon the right hand of the under set of rollers. The second motion, that of the spindles, is effected by the drum _z_, which extends the whole length of the frame, turning upon the shaft _v_, and communicating its rotatory movement (derived from the steam pulley) to the whorl _b´_, of the spindles, by means of the endless band or cord _a´_. Each of these cords turns four spindles, two upon each side of the frame. They are kept in a proper state of tension by the weights _c´_, which act tangentially upon the circular arc _d´_, fixed to the extremity of the bell-crank lever _e´ f´ g´_, and draw in a horizontal direction the tension pulleys _h_, embraced by the cords. The third movement, or the vertical traverse of the bobbins, along the spindles _m_, takes place as follows:--

The end of one of the under rollers carries a pinion, which takes into a carrier wheel, that communicates motion to a pinion upon the extremity of the shaft _m´_, of the heart-shaped pulley _n´_. As this eccentric revolves, it gives a reciprocating motion to the levers _o´_, _o´_, which oscillate in a vertical plane round the points, _p´_, _p´_. The extremities of these levers, on either side, act by means of the links _q´_, upon the arms of the sliding sockets _r´_, and cause the vertical rod _s´_, to slide up and down in guide-holes at _t´_, _u´_, along with the cast-iron step _v´_, which bears the bottom washer of the bobbins. The periphery of the heart-wheel _n´_, is seen to bear upon friction wheels _x_, _x´_, set in frames adjusted by screws upon the lower end of the bent levers, at such a distance from the point _p´_, as that the traverse of the bobbins may be equal to the length of their barrel.

By adapting change pinions and their corresponding wheels to the rollers, the delivery of the yarn may be increased or diminished in any degree, so as to vary the degree of twist put into it by the uniform rotation of the drum and spindles. The heart motion being derived from that of the rollers, will necessarily vary with it.

Silk thread is commonly twisted in lengths of from 50 to 100 feet, with hand reels, somewhat similar to those employed for making ropes by hand.

TILES. See BRICKS.

TILTING OF STEEL. See STEEL. Rees’s Cyclopædia contains an excellent article on this subject.

TIN (_Etain_, Fr.; _Zinn_, Germ.); in its pure state, has nearly the colour and lustre of silver. In hardness it is intermediate between gold and lead; it is very malleable, and may be laminated into foil less than the thousandth of an inch in thickness; it has an unpleasant taste, and exhales on friction a peculiar odour; it is flexible in rods or straps of considerable strength, and emits in the act of bending a crackling sound, as if sandy particles were intermixed, called the creaking of tin. A small quantity of lead, or other metal, deprives it of this characteristic quality. Tin melts at 442° Fahr., and is very fixed in the fire at higher heats. Its specific gravity is 7·29. When heated to redness with free access of air, it absorbs oxygen with rapidity, and changes first into a pulverulent gray protoxide, and by longer ignition, into a yellow-white powder, called _putty_ of tin. This is the peroxide, consisting of 100 of metal + 27·2 of oxygen.

Tin has been known from the most remote antiquity; being mentioned in the books of Moses. The Phœnicians carried on a lucrative trade in it with Spain and Cornwall.

There are only two ores of tin; the peroxide, or tin-stone, and tin pyrites; the former of which alone has been found in sufficient abundance for metallurgic purposes. The external aspect of tin-stone has nothing very remarkable. It occurs sometimes in twin crystals; its lustre is adamantine; its colours are very various, as white, gray, yellow, red, brown, black; specific gravity 6·9 at least; which is, perhaps, its most striking feature. It does not melt by itself before the blowpipe; but is reducible in the smoky flame or on charcoal. It is insoluble in acids. It has somewhat of a greasy aspect; and strikes fire with steel.

Tin-stone occurs disseminated in the antient rocks, particularly granite; also in beds and veins, in large irregular masses, called _stockwerks_; and in pebbles, an assemblage of which is called stream-works, where it occasionally takes a ligneous aspect, and is termed _wood-tin_.

This ore has been found in few countries in a workable quantity. Its principal localities are, Cornwall, Bohemia, Saxony, in Europe; and Malacca and Banca, in Asia. The tin-mines of the Malay peninsula lie between the 10th and 6th degree of south latitude; and are most productive in the island of Junck-Ceylon, where they yield sometimes 800 tons per annum, which are sold at the rate of 48_l._ each. The ores are found in large caves near the surface; and though actively mined for many centuries, still there is easy access to the unexhausted parts. The mines in the island of Banca, to the east of Sumatra, discovered in 1710, are said to have furnished, in some years, nearly 3500 tons of tin. Small quantities occur in Gallicia in Spain, in the department of Haute Vienne in France, and in the mountain chains of the Fichtel and Riesengebürge in Germany. The columnar pieces of pyramidal tin-ore from Mexico and Chile, are products of stream-works. Small groups of black twin crystals have been lately discovered in the albite rock of Chesterfield in Massachusetts.

The Cornish ores occur--1. in small strata or veins, or in masses; 2. in stockwerks, or congeries of small veins; 3. in large veins; 4. disseminated in alluvial deposits.

The stanniferous small veins, or thin flat masses, though of small extent, are sometimes very numerous, interposed between certain rocks, parallel to their beds, and are commonly called tin-floors. The same name is occasionally given to stockwerks. In the mine of Bottalack, a _tin-floor_ has been found in the killas (primitive schistose rock), thirty-six fathoms below the level of the sea; it is about a foot and a half thick, and occupies the space between a principal vein and its ramification; but there seems to be no connexion between the _floor_ and the great vein.

2. Stockwerks occur in granite and in the felspar porphyry, called in Cornwall, _elvan_. The most remarkable of these in the granite, is at the tin-mine of Carclase, near _St. Austle_. The works are carried on in the open air, in a friable granite, containing felspar disintegrated into _kaolin_, or china clay, which is traversed by a great many small veins, composed of tourmaline, quartz, and a little tin-stone, that form black delineations on the face of the light-gray granite. The thickness of these little veins rarely exceeds 6 inches, including the adhering solidified granite, and is occasionally much less. Some of them run nearly east and west, with an almost vertical dip; others, with the same direction, incline to the south at an angle with the horizon of 70 degrees.

Stanniferous stockwerks are much more frequent in the elvan (porphyry); of which the mine of Trewidden-ball is a remarkable example. It is worked among flattened masses of _elvan_, separated by strata of _killas_, which dip to the east-north-east at a considerable angle. The tin ore occurs in small veins, varying in thickness from half an inch to 8 or 9 inches, which are irregular, and so much interrupted, that it is difficult to determine either their direction or their inclination.

3. The large and proper metalliferous veins are not equally distributed over the surface of Cornwall and the adjoining part of Devonshire; but are grouped into three districts; namely, 1. In the south-west of Cornwall, beyond Truro; 2. In the neighbourhood of St. Austle; and 3. In the neighbourhood of Tavistock in Devonshire.

The first group is by far the richest, and the best explored. The formation most abundant in tin mines is principally granitic; whilst that of the copper mines is most frequently schistose or killas; though with numerous exceptions. The great tin veins are the most antient metalliferous veins in Cornwall; yet they are not all of one formation, but belong to two different systems. Their direction is, however, nearly the same, but some of them dip towards the north, and others towards the south. The first are older than the second; for in all the mines where these two sets of veins are associated, the one which dips to the north, cuts across and throws out the one which dips to the south. See MINES, p. 835.

At Trevannance mines, the two systems of tin veins are both intersected by the oldest of the copper veins; indicating the prior existence of the tin veins. In _fig._ 1139. _b_, marks the first system of tin veins; _c_, the second; and _d_, the east and west copper veins. Some of these tin veins, as at Poldice, have been traced over an extent of two miles; and they vary in thickness from a small fraction of an inch to several feet, the average width being from 2 to 4 feet; though this does not continue uniform for any length, as these veins are subject to continual narrowings and expansions. The gangue is quartz, chlorite, tourmaline, and sometimes decomposed granite and fluor spar.

4. _Alluvial tin ore, stream tin._--Peroxide of tin occurs disseminated both in the _alluvium_ which covers the gentle slopes of the hills adjoining the rich tin-mines, and also in the alluvium which fills the valleys that wind round their base; but in these numerous deposits the tin-stone is rarely distributed in sufficient quantities to make it worth the working. The most important explorations of _alluvial tin ore_ are grouped in the environs of St. Just and St. Austle; where they are called _stream-works_; because water is the principal agent employed to separate the metallic oxide from the sand and gravel.

The tin mine of Altenberg, in Saxony (_fig._ 1140., which is a vertical projection in a plane passing from west to east,) is remarkable for a stockwerke, or interlaced mass of ramifying veins, which has been worked ever since the year 1458. The including rock is a primitive porphyry, superposed upon gneiss; becoming very quartzose as it approaches the lode. This is usually disseminated in minute particles, and accompanied with wolfram, copper and arsenical pyrites, _fer oligiste_, sulphuret of molybdenum, and bismuth, having gangues of lithomarge, fluor spar, mica, and felspar. The space which the ore occupies in the heart of the quartz, is a kind of dædalus, the former being often so dispersed among the latter as to seem to merge into it; whence it is called by the workmen _zwitter_, or _ambiguous_. In 1620, the mine was worked by 21 independent companies, in a most irregular manner, whereby it was damaged to a depth of 170 fathoms by a dreadful downfall of the roofs. This happened on a Sunday, providentially, when the pious miners were all at church. The depth of this abyss, marked by the curved line _b_, _b_, _b_, is 66 fathoms; but the devastation is manifest to a depth of 95 fathoms below that curve, and 35 fathoms below the actual workings, represented at the bottom of the shaft under B. The parts excavated are shaded black in the figure. There are two masses of ore, one under the shaft B, and another under the shaft C; which at the levels 5 and 10 are in communication, but not at 6, 7. There is a direct descent from 8 to 9. The deposits are by no means in one vertical plane, but at a considerable horizontal distance from each other. A is the descending shaft; B is the extraction shaft, near the mouth of which there is a water-wheel; C is another extraction shaft, worked also by means of a water-wheel. A and C are furnished with ladders, but for B the ladders are placed in an accessory shaft _b´_; under D, a shaft is sunk for pumping out the water, by means of an hydraulic wheel at D; E is the gallery or drift for admitting the water which drives the wheels. This falls 300 feet, and ought to be applied to a water-pressure engine, instead of the paddles of a wheel. At D, is the gallery of discharge for the waters, which serves also to ventilate the mine, being cut to the day, through 936 toises of syenitic porphyry and gneiss. J, is a great vaulted excavation. The mine has 13 stages of galleries, of which 11 serve for extracting the ore; 1 is the mill-course; the rest are marked with the numbers 2, 3, 4, &c.; each having besides a characteristic German name. The rare mineral called _topaz pycnite_ is found in this mine, above 10, between the shafts C and D.

The only rule observed in taking ore from this mine, has been to work as much out of each of these levels as is possible, without endangering the superincumbent or collateral galleries; on which account many pillars are constructed to support the roofs. The mine yields annually 1600 quintals (Leipzick) of tin, being four-fifths of the whole furnished by the district of Altenberg; to produce which, 400,000 quintals of ore are raised. 1000 parts of the rock yield 8 of concentrated schlich, equivalent to only 4 of metal; being only 1 in 250 parts.

But the most extensive and productive stream-works, are those of Pentowan, near St. Austle.

_Fig._ 1141. represents a vertical section of the Pentowan mine, taken from the _stream-work_, _Happy Union_. A vast excavation, R, T, U, S, has been hollowed out in the open air, in quest of the alluvial tin ore T, which occurs here at an unusual depth, below the level of the strata R, S. Before getting at this deposit, several successive layers had to be sunk through; namely, 1, 2, 3; the gravel, containing in its middle a band of ochreous earth 2, or ferruginous clay; 4, a black peat, perfectly combustible, of a coarse texture, composed of reeds and woody fibres, cemented into a mass by a fine loam; 5, coarse sea-sand, mingled with marine shells; 6, a blackish marine mud, filled with shells. Below these the deposit of tin-stone occurs, including fragments of various size, of clay slate, flinty slate, quartz, iron ore, jasper; in a word, of all the rocks and gangues to be met with in the surrounding territory, with the exception of granite. Among these fragments there occur, in rounded particles, a coarse quartzose sand, and the tin-stone, commonly in small grains and crystals. Beneath the bed T, the clay slate occurs, called _killas_ (A, X, Y), which supports all the deposits of more recent formation.

The system of mining is very simple. The successive beds, whose thickness is shown in the figure, are visibly cut out into steps or platforms. By a level or gallery of efflux _k_, the waters flow into the bottom of the well _l_, _m_, which contains the drainage pumps; and these are put in action by a machine _j_, moved by a water-wheel. The extraction of the ore is effected by an inclined plane _i_, cut out of one of the sides of the excavation, at an angle of about 45 degrees. At the lower end of this sloping pathway there is a place of loading; and at its upper end _h_, a horse-gin, for alternately raising and lowering the two baskets of extraction on the pathway _i_.

_Mine tin_ requires peculiar care in its mechanical preparation or dressing, on account of the presence of foreign metals, from which, as we have stated, the stream tin is free.

1. As the mine tin is for the most part extremely dispersed through the gangue, it must be all stamped and reduced to a very fine powder, to allow the metallic particles to be separated from the stony matters.

2. As the density of tin-stone is much greater than that of most other metallic ores, it is less apt to run off in the washing; and may, therefore, be dressed so as to be completely stripped of every matter not chemically combined.

3. As the peroxide of tin is not affected by a moderate heat, it may be exposed to calcination; whereby the specific gravity of the associated sulphurets and arseniurets is so diminished as to facilitate their separation.

We may therefore conclude, that tin ore should be first of all pounded very fine in the stamp-mill, then subjected to reiterated washings, and afterwards calcined. The order of proceeding in Cornwall is as follows:--

1. _Cleaning the ore._--This is usually done at the mouth of the gallery of efflux, by agitating the ore in the stream of water as it runs out. Sometimes the ore is laid on a grating, under a fall of water.

2. _Sorting._--The ore thus cleaned, is sorted on the grate, into four heaps: 1. stones rich in tin; 2. stones containing both tin and copper ore; 3. copper ore; 4. sterile pieces, composed in a great measure of stony gangue, with iron and arsenical pyrites. In those veins where there is no copper ore, the second and third heaps are obviously absent. When present, the compound ore is broken into smaller pieces with a mallet, and the fragments are sorted anew.

3. _Stamping._--The stanniferous fragments (No. 1.) are stamped into a sand, of greater or less fineness, according to the dissemination of the tin-stone in the gangue. The determination of the size of the sand, is an object of great importance. It is regulated by a copper plate pierced with small holes, through which every thing from the stamping-mill must run off with the rapid stream introduced for this purpose. This plate forms the front of the stamp cistern.

Several years ago, all the stamp mills were driven by water-wheels, which limited the quantity of ore that could be worked to the hydraulic power of the stream or waterfall; but since the steam engine has been applied to this purpose, the annual product of tin has been greatly increased. On the mine of Huel Vor, there are three steam engines appropriated to the stamping-mills. Their force is 25 horses at least. One of these machines, called _south stamps_, drives 48 pestles; a second, called _old stamps_, drives 36; and a third, 24. The weight of these pestles varies from 370 to 387 pounds; and they generally rise through a space of 10-1/2 inches. The machine called _south stamps_, the strongest of the three, gives 17-1/2 blows in the minute, each pestle being lifted twice for every stroke of the piston. The steam engine of this mill has a power of 25 horses, and it consumes 1062 bushels of coals in the month. Three pestles constitute a battery, or stamp-box.

_Washing and stamping of tin ores at Polgooth, near St. Austle._--The stamps or pestles are of wood, 6 inches by 5-1/2 in the square: they carry lifting bars _b_, secured with a wooden wedge and a bolt of iron, and they terminate below in a lump of cast iron A, called the head, which is fastened to them by a tail, and weighs about 2-1/2 cwts. The shank of the pestle is strengthened with iron hoops. A turning-shaft communicates motion to the stamps by cams stuck round its circumference, so arranged that the second falls while the first and third of each set are uplifted. There are 4 cams on one periphery, and the shaft makes 7 turns in the minute. Each stamp, therefore, gives 28 strokes per minute, and falls through a space of 7-1/2 inches. The stamp chest is open behind, so that the ore slips away under the pestles, by its weight, along the inclined plane with the stream of water. The bottom of the troughs consists of stamped ores. With 6 batteries of 6 pestles each, at Poldice, near Redruth, 120 bags of ore are stamped in 12 hours; each bag containing 18 gallons of 282 cubic inches; measuring altogether 352 cubic feet, and 864 cubic inches.

The openings in the front sides of the troughs are nearly 8 inches by 7-1/2: they are fitted with an iron frame, which is closed with sheet iron, pierced with about 160 holes in the square inch, bored conically, being narrower within. The ore, on issuing, deposits its _rough_ in the first basin, and its slimes in the following basins. The rough is washed in _buddles_ (see LEAD, page 751), and in _tossing tubs_; the slimes in _trunks_, and upon a kind of twin tables, called _racks_. Into the _tossing-tub_, or _dolly_, _fig._ 1143., the stamped ore is thrown, along with a certain quantity of water, and a workman stirs it about with an iron shovel for three or four minutes. He then removes a little of the water with a handled pitcher, and strikes the sides of the tub for 8 or 10 minutes with a hammer, which hastens the subsidence of the denser parts. The water is next poured off by inclining the tub to one side. In one operation of this kind, four distinct strata of the ores may be procured, as indicated by the lines _a b_, _c d_, _e f g_, _h i k_, in the figure. The portion A is to be washed again in the _trunking-box_, _figs._ 1144, 1145.; B is to be washed upon the German chests or racks, _fig._ 1146.; C, the most considerable, is put aside, as schlich fit for the market; D, forming a nucleus the centre of the tub, is to be passed through sieves of copper wire, having 18 meshes in the square inch. This product thus affords a portion D´, which passes through the sieve, and D´´ which remains upon it; the latter is sometimes thrown away, and at others is subjected to the operation called the _tie_, viz., a washing upon the sloping bottom of a long trough.

The slimes are freed from the lighter mud in the trunking-box, _figs._ 1144, 1145.; which is from 7 to 8 feet long. Being accumulated at M, the workman pushes them back with a shovel from _a_ towards _b_. The metallic portion is carried off, and deposited by the stream of water upon the table; but the earthy matters are floated along into a basin beyond it. The product collected in the chest is divided into two portions; the one of which is washed once, and the other twice, upon the _rack_, _fig._ 1146. This is composed of a frame C, which carries a sloping board or table, susceptible of turning round to the right or left upon two pivots, K, K. The head of the table is the inclined plane T. A small board P, which is attached by a band of leather L, forms the communication with the lower table C, whose slope is generally 5 inches in its whole length of 9 feet; but this may vary with the nature of the ore, being somewhat less when it is finely pulverized. The ore is thrown upon T, in small portions of 20 or 25 lbs. A woman spreads it with a rake, while a stream of water sweeps a part of it upon the table, where it gets washed. The fine mud falls through a cross slit near the lower end, into a basin B. After working for a few minutes, should the schlich seem tolerably rich, the operative turns the table round its axis K, K, so as to tumble it into the boxes below. The mud is in B; an impure schlich in B´, which must be washed again upon the _rack_; and a schlich fit for roasting in B´´.

The slope of the rack-table for washing the _roasted_ tin ore, is 7-3/4 inches in the 9 feet.

_Crushing rolls at the Pembroke mines._--Waggons, moved on a railway by an endless rope, bring the ore to be crushed, immediately over the rolls, as shown in _fig._ 1147. A trap being opened in the side of the waggon, the ore falls into the hopper T, whence it passes directly between the twin cylinders C, C, and next upon the sieve D, which receives a seesaw motion horizontally, by means of the rod L, and the crank of the upright turning-shaft. The finer portion of ore, which passes through that sieve, forms the heap S. The coarser portion is tossed over the edge of the sieve, and falls between the cylinders C´ C´, upon a lower level, and forms the second heap S´ of sifted, and S´´ of unsifted, ore.

The holes of the sieves D, D´, being of the same size, the products S, S´, are of the same fineness. S´´ is ground again, being mixed, in the uppermost hopper T, along with the lumps from the waggons.

The diameter and length of the under rolls (see _fig._ 1148.) are each 16 inches. _a b_, is the square end of the gudgeon _t_, which prevents the shaft shifting laterally out of its place. The diameter of the upper rolls is 18 inches, but their length is the same. Both are made of white cast iron, _chilled_ or case-hardened by being cast in iron moulds instead of sand; and they last a month, at least, when of good quality. They make from 10 to 15 turns in a minute, according to the hardness of the ores of tin or copper; and can grind about 50 tons of rich copper ore in 12 hours; but less of the poorer sort.

The next process is the calcination in the _burning-house_; which includes several reverberatory furnaces. At the mine of Poldice, they are 4 or 5 yards long, by from 2-1/2 to 3 yards wide. Their hearth is horizontal; the elevation, about 26 inches high near the fireplace, sinks slightly towards the chimney. There is but one opening, which is in the front; it is closed by a plate-iron door, turning on hinges. Above the door there is a chimney, to let the sulphureous and arsenical vapours fly off, which escape out of the hearth, without annoying the workmen. This chimney leads to horizontal flues, in which the arsenious acid is condensed.

Six hundred weight of ore are introduced; the calcination of which takes from 12 to 18 hours, according to the quantity of pyrites contained in the ore. At the beginning of the operation, a moderate heat is applied, after which it is pushed to a dull red, and kept so during several hours. The door is shut; the materials are stirred from time to time with an iron rake, to expose new surfaces, and prevent them from agglutinating or _kerning_, as the workmen say. The more pyrites is present, the more turning is necessary. Should the ore contain black oxide of iron, it becomes peroxidized, and is then easily removed by a subsequent washing.

_Figs._ 1149, 1150. represent the furnace employed at Altenberg, in Saxony, for roasting tin ores. _a_ is the grate; _b_, the sole of the roasting hearth; _c_, an opening in the arched roof for introducing the dried schlich (the ground and elutriated ore); _d_, is the smoke-mantle or chimney-hood, at the end of the furnace, under which the workmen turn over the spread schlich, with long iron rods bent at their ends; _e_, is the poison vent, which conducts the arsenical vapours to the poison chamber (_gifthaus_) of condensation.

When the ore is sufficiently calcined, as is shown by its ceasing to exhale vapours, it is taken out, and exposed for some days to the action of the air, which decomposes the sulphurets, or changes them into sulphates. The ore is next put into a tub filled with water, stirred up with a wooden rake, and left to settle; by which means the sulphate of copper that may have been formed, is dissolved out. After some time, this water is drawn off into a large tank, and its copper recovered by precipitation with pieces of old iron. In this way, almost all the copper contained in the tin ore is extracted.

The calcined ore is sifted, and treated again on the racks, as above described. The pure schlich, called _black tin_, is sold under this name to the smelters; and that which collects on the middle part of the inclined wash-tables, being much mixed with wolfram, is called _mock lead_. This is passed once more through the stamps, and washed; when it also is sold as _black tin_.

Stream tin is dressed by similar methods: 1. by washing in a trunking-box, of such dimensions that the workman stands upon it in thick boots, and makes a skilful use of the rake; 2. by separating the larger conglomerate pebbles from the smaller pure ones; picking, stamping, and washing, on a kind of _sleeping-tables_. See METALLURGY, _figs._ 677, 678.

The tin ores of Cornwall and Devonshire are all reduced within the counties where they are mined, as the laws prohibit their exportation out of them. Private interests suffer no injury from this prohibition; because the vessels which bring the fuel from Wales, for smelting these ores, return to Swansea and Neath loaded with copper ores.

The smelting-works belong in general to individuals who possess no tin mines, but who purchase at the cheapest rate the ores from the mining proprietors. The ores are appraised according to their contents in metal, and its fineness; conditions which they determine by the following mode of assay. When a certain number of bags of ore, of nearly the same quality, are brought to the works, a small sample is taken from each bag, and the whole are well blended. Two ounces of this average ore are mixed with about 4 per cent. of ground coal, put into an open earthen crucible, and heated in an air furnace (in area about 10 inches square) till reduction takes place. As the furnace is very hot when the crucible is introduced, the assay is finished in about a quarter of an hour. The metal thus revived, is poured into a mould, and what remains in the crucible is pounded in a mortar, that the grains of tin may be added to the ingot.

This method, though imperfect in a chemical point of view, serves the smelter’s purpose, as it affords him a similar result to what he would get on the great scale. A more exact assay would be obtained by fusing, in a crucible lined with hard-rammed charcoal, the ore mixed with 5 per cent. of ground glass of borax. To the crucible a gentle heat should be applied during the first hour, then a strong heat during the second hour, and, lastly, an intense heat for a quarter of an hour. This process brings out from 4 to 5 per cent. more tin than the other; but it has the inconvenience of reducing the iron, should any be present; which by subsequent solution in nitric acid will be readily shown. This assay would be too tedious for the smelter, who may have occasion to try a great many samples in one day.

The smelting of tin ores is effected by two different methods:--

In the first, a mixture of the ore with charcoal is exposed to heat on the hearth of a reverberatory furnace fired with coal.

In the second, the tin ore is fused in a blast furnace, called a blowing-house, supplied with wood charcoal. This method is practised in only a few works, in order to obtain a very pure quality of tin, called _grain tin_ in England, and _étain en larmes_ in France; a metal required for certain arts, as dyeing, &c. This method is applied merely to stream tin.

In the _smelting-houses_, where the tin is worked in reverberatories, two kinds of furnaces are employed; the reduction and the refining furnaces.

_Figs._ 1151, 1152. represent the furnaces for smelting tin at St. Austle, in Cornwall; the former being a longitudinal section, the latter a ground plan, _a_ is the fire-door, through which pitcoal is laid upon the grate _b_; _c_ is the fire-bridge; _d_, the door for introducing the ore; _e_, the door through which the ore is worked upon the hearth _f_; _g_, the stoke-hole; _h_, an aperture in the vault or roof, which is opened at the discharge of the waste schlich, to secure the free escape of the fumes up the chimney; _i_, _i_, air channels, for admitting cold air under the fire-bridge and the sole of the hearth, with the view of protecting them from injury by the intensity of the heat above. _k_, _k_, are basins into which the melted tin is drawn off; _l_, the flue; _m_, the chimney, from 35 to 50 feet high. The roasted and washed schlich is mixed with small coal or culm, along with a little slaked lime, or fluor spar, as a flux; each charge of ore amounts to from 15 to 24 cwt., and contains from 60 to 70 per cent. of metal.

_Fig._ 1153. represents in a vertical section through the tuyère, and _fig._ 1154. in a horizontal section, in the dotted line _x_, _x_, of _fig._ 1153., the furnace employed for smelting tin at the Erzgebirge mines, in Saxony. _a_, are the furnace pillars, of gneiss; _b_, _b_, are shrouding or casing walls; _c_, the tuyère wall; _d_, front wall, both of granite; as also the tuyère _e_. _f_, the sole-stone, of granite, hewn out basin-shaped; _g_, the _eye_, through which the tin and slag are drawn off into the fore-hearth _h_; _i_, the stoke-hearth; _k_, _k_, the light ash chambers; _l_, the arch of the tuyère; _m_, _m_, the common flue, which is placed under the furnace and the hearths, and has its outlet under the vault of the tuyère.

In the smelting furnaces at Geyer the following dimensions are preferred:--Length of the tuyère wall, 11 inches; of the breast wall, 11 inches; depth of the furnace, 17 inches. High chimney-stalks are advantageous where a great quantity of ores is to be reduced, but not otherwise.

The _refining furnaces_ are similar to those which serve for reducing the ore; only, instead of a basin of reception, they have a refining basin placed alongside, into which the tin is run. This basin is about 4 feet in diameter, and 32 inches deep; it consists of an iron pan, placed over a grate, in which a fire may be kindled. Above this pan there is a turning gib, by means of which a billet of wood may be thrust down into the bath of metal, and kept there by wheeling the gibbet over it, lowering a rod, and fixing it in that position.

The works in which the blast furnaces are employed, are called _blowing-houses_. The smelting furnaces are 6 feet high, from the bottom of the crucible (concave hearth) to the throat, which is placed at the origin of a long and narrow chimney, interrupted by a chamber, where the metallic dust, carried off by the blast, is deposited. This chamber is not placed vertically over the furnace; but the lower portion of the chimney has an oblique direction from it. The furnace is lined with an upright cylinder of cast iron, coated internally with loam, with an opening in it for the blast. This opening, which corresponds to the lateral face opposite to the charging side, receives a _tuyère_, in which the nozzles of two cylinder single bellows, driven by a water-wheel, are planted. The _tuyère_ opens at a small height above the sole of the furnace. On a level with the sole, the iron cylinder presents a slope, below which is the hemispherical basin of reception, set partly beneath the interior space of the furnace, and partly without. Near the corner of the building there is a second basin of reception, larger than the first, which can discharge itself into the former by a sloping gutter. Near this basin there is another, for the refining operation. These are all made either of brick or cast iron.

The quality of the average ground-tin ore prepared for smelting is such, that 20 parts of it yield from 12-1/2 to 13 of metallic tin, (62-1/2 to 65 per cent.) The treatment consists of two operations, _smelting_ and _refining_.

_First operation; deoxidization of the ore, and fusion of the tin._--Before throwing the ore into the smelting furnace, it is mixed with from one-fifth to one-eighth of its weight of _blind coal_, in powder, called _culm_; and a little slaked lime is sometimes added, to render the ore more fusible. These matters are carefully blended, and damped with water, to render the charging easier, and to prevent the blast from sweeping any of it away at the commencement. From 12 to 16 cwt. are introduced at a charge; and the doors are immediately closed and luted, while the heat is progressively raised. Were the fire too strong at first, the tin oxide would unite with the quartz of the gangue, and form an enamel. The heat is applied for 6 or 8 hours, during which the doors are not opened; of course the materials are not stirred. By this time the reduction is, in general, finished; the door of the furnace is removed, and the melted mass is worked up to complete the separation of the tin from the scoriæ, and to ascertain if the operation be in sufficient forwardness. When the reduction seems to be finished, the scoriæ are taken out at the same door, with an iron rake, and divided into three sorts; those of the first class A, which constitute at least three-fourths of the whole, are as poor as possible, and may be thrown away; the scoriæ of the second class B, which contain some small grains of tin, are sent to the stamps; those of the third class C, which are last removed from the surface of the bath of tin, are set apart, and re-smelted, as containing a considerable quantity of metal in the form of grain tin. These scoriæ are in small quantity. The stamp slag contains fully 5 per cent. of metallic tin.

As soon as the scoriæ are cleared away, the channel is opened which leads to the basin of reception, into which the tin consequently flows out. Here it is left for some time, that the scoriæ which may be still mixed with the metal, may separate, in virtue of the difference of their specific gravities. When the tin has sufficiently settled, it is lifted out with ladles, and poured into cast-iron moulds, in each of which a bit of wood is fixed, to form a hole in the ingot, for the purpose of drawing it out when it becomes cold.

_Refining of tin._--The object of this operation is to separate from the tin, as completely as possible, the metals reduced and alloyed along with it. These are, principally, iron, copper, arsenic, and tungsten; to which are joined, in small quantities, some sulphurets and arseniurets that have escaped decomposition, a little unreduced oxide of tin, and also some earthy matters which have not passed off with the scoriæ.

_Liquation._--The refining of tin consists of two operations; the first being a liquation, which, in the interior, is effected in a reverberatory furnace, similar to that employed in smelting the ore. (_figs._ 1151, 1152.) The blocks being arranged on the hearth of the furnace, near the bridge, are moderately heated; the tin melts, and flows away into the refining-basin; but, after a certain time, the blocks cease to afford tin, and leave on the hearth a residuum, consisting of a very ferruginous alloy.

Fresh tin blocks are now arranged on the remains of the first; and thus the liquation is continued till the refining-basin be sufficiently full, when it contains about 5 tons. The residuums are set aside, to be treated as shall be presently pointed out.

_Refining proper._--Now begins the second part of the process. Into the tin-bath, billets of green wood are plunged, by aid of the gibbet above described. The disengagement of gas from the green wood produces a constant ebullition in the tin; bringing up to its surface a species of froth, and causing the impurest and densest parts to fall to the bottom. That froth, composed almost wholly of the oxides of tin and foreign metals, is successively skimmed off, and thrown back into the furnace. When it is judged that the tin has boiled long enough, the green wood is lifted out, and the bath is allowed to settle. It separates into different zones, the upper being the purest; those of the middle are charged with a little of the foreign metals; and the lower are much contaminated with them. When the tin begins to cool, and when a more complete separation of its different qualities cannot be looked for, it is lifted out in ladles, and poured into cast-iron moulds. It is obvious, that the order in which the successive blocks are obtained, is that of their purity; those formed from the bottom of the basin being usually so impure, that they must be subjected anew to the refining process, as if they had been directly smelted from the ore.

The refining operation takes 5 or 6 hours; namely, an hour to fill the basin, three hours to boil the tin with the green wood, and from one to two hours for the subsidence.

Sometimes a simpler operation, called _tossing_, is substituted for the above artificial ebullition. To effect it, a workman lifts some tin in a ladle, and lets it fall back into the boiler, from a considerable height, so as to agitate the whole mass. He continues this manipulation for a certain time; after which, he skims with care the surface of the bath. The tin is afterwards poured into moulds, unless it be still impure. In this case, the separation of the metals is completed by keeping the tin in a fused state in the boiler for a certain period, without agitation; whereby the upper portion of the bath (at least one-half) is pure enough for the market.

The moulds into which the tin blocks are cast, are usually made of granite. Their capacity is such, that each block shall weigh a little more than three hundred weight. This metal is called block tin. The law requires them to be stamped or _coined_ by public officers, before being exposed to sale. The purest block tin is called refined tin.

The treatment just detailed gives rise to two stanniferous residuums, which have to be smelted again. These are--

1. The scoriæ B and C, which contain some granulated particles of tin.

2. The dross found on the bottom of the reverberatory furnace, after re-melting the tin to refine it.

The scoriæ C, are smelted without any preparation; but those marked B, are stamped in the mill, and washed, to concentrate the tin grains; and from this rich mixture, called _prillion_, smelted by itself, a tin is procured of very inferior quality. This may be readily imagined, since the metal which forms these granulations is what, being less fusible than the pure tin, solidified quickly, and could not flow off into the metallic bath.

Whenever all the tin blocks have thoroughly undergone the process of liquation, the fire is increased, to melt the less fusible residuary alloy of tin with iron and some other metals, and this is run out into a small basin, totally distinct from the refining basin. After this alloy has reposed for some time, the upper portion is lifted out into block moulds, as impure tin, which needs to be refined anew. On the bottom and sides of the basin there is deposited a white, brittle alloy, with a crystalline fracture, which contains so great a proportion of foreign metals, that no use can be made of it. About 3-1/2 tons of coal are consumed in producing 2 of tin.

_Smelting of tin by the blast furnace._--This mode of reduction employs only wood charcoal, and its object is to obtain tin of the maximum purity to which it can be brought by manufacturing processes. The better ores of the stream-works, and the finer tin sands, are selected for this operation. The washings being always well performed, the oxide of tin is exempt from every arsenical or sulphureous impurity, and is associated with nothing but a little hematite. It is therefore never calcined.

The smelting is effected without addition; only, in a few cases, some of the residuary matters of a former operation are added to the ore. About a ton and six-tenths of wood charcoal are burned for one ton of fine smelted tin. The only rule is, to keep the furnace always full of charcoal and ore. The revived tin is received immediately in the first basin; then run off into the second, where it is allowed to settle for some time. The scoriæ that run off into the first basin, are removed as soon as they fix. These scoriæ are divided into two classes; namely, such as still retain tin oxide, and such as hold none of the metal in that state, but only in granulations. The metallic bath is divided, by repose, into horizontal zones, of different degrees of purity; the more compound and denser matters falling naturally to the bottom of the basin. The tin which forms the superior zones, being judged to be pure enough, is transvased by ladles into the refining basin, previously heated, and under which, if it is of cast-iron, a moderate fire is applied. The tin near the bottom of the receiving basin is always laded out apart, to be again smelted; sometimes, indeed, when the furnace is turning out very impure tin, none of it is transvased into the second basin; but the whole is cast into moulds, to be again treated in the blast furnace.

In general they receive no other preparation, but the green wood ebullition, before passing into the market. Sometimes, however, the block of metal is heated till it becomes brittle, when it is lifted to a considerable height, and let fall, by which it is broken to pieces, and presents an agglomeration of elongated grains or _tears_; whence it is called _grain tin_.

On making a comparative estimate of the expense by the _blowing-house_ process, and by the reverberatory furnace, it has been found that the former yields about 66 per cent. of tin, in smelting the stream or alluvial ore, whose absolute contents are from 75 to 78 parts of metal in the hundred. One ton of tin consumes a ton and six-tenths of wood charcoal, and suffers a loss of 15 per cent. In working with the reverberatory furnace, it is calculated that ore whose mean contents by an exact analysis are 70 per cent., yields 65 per cent. on the great scale. The average value of tin ore, as sold to the smelter, is 50 pounds sterling per ton; but it fluctuates, of course, with the market prices. In 1824, the ore of inferior quality cost 30_l._, while the purest sold for 60_l._ One ton of tin, obtained from the reverberatory furnace, cost--

1-1/2 tons of ore, worth _£_75 0 0 1-3/4 tons of coals, at 10_s._ per ton 0 17 6 Wages of labour, interest on capital, &c. 3 0 0 --------- 78 17 6

On comparing these results with the former, we perceive that in a _blowing-house_ the loss of tin is 15 per cent., whereas it is only 5 in the reverberatory furnace. The expense in fuel is likewise much less relatively in the latter process; for only 1-3/4 tons of coals are consumed for one ton of tin; while a ton and six-tenths of wood charcoal are burned to obtain the same quantity of tin in the blowing-house; and it is admitted that one ton of wood charcoal is equivalent to two tons of coal, in calorific effect. Hence every thing conspires to turn the balance in favour of the reverberatory plan. The operation is also, in this way, much simpler, and may be carried on by itself. The scoriæ, besides, from the reverberatory hearth, contain less tin than those derived from the same ores treated with charcoal by the blast, as is done at Altenberg. It must be remembered, however, that the grain tin procured by the charcoal process is reckoned to be finer, and fetches a higher price; a superiority partly due to the purity of the ore reduced, and partly to the purity of the fuel.

To test the quality of tin, dissolve a certain weight of it with heat in muriatic acid; should it contain arsenic, brown-black flocks will be separated during the solution, and arseniuretted hydrogen gas will be disengaged, which, on being burned at a jet, will deposit the usual gray film of metallic arsenic upon a white saucer held a little way above the flame. Other metals present in the tin, are to be sought for, by treating the above solution with nitric acid of spec. grav. 1·16, first in the cold, and at last with heat and a small excess of acid. When the action is over, the supernatant liquid is to be decanted off the peroxidized tin, which is to be washed with very dilute nitric acid, and both liquors are to be evaporated to dissipate the acid excess. If, on the addition of water to the concentrated liquor, a white powder falls, it is a proof that the tin contains bismuth; if on adding sulphate of ammonia, a white precipitate appears, the tin contains lead; water of ammonia added to supersaturation, will occasion reddish-brown flocks, if iron is present; and on evaporating the supernatant liquid to dryness, the copper will be obtained.

The uses of tin are very numerous. Combined with copper, in different proportions, it forms bronze, and a series of other useful alloys; for an account of which see COPPER. With iron, it forms tin-plate; with lead, it constitutes pewter, and solder of various kinds (see LEAD). Tin-foil coated with quicksilver makes the reflecting surface of glass mirrors. (See GLASS.) Nitrate of tin affords the basis of the scarlet dye on wool, and of many bright colours to the calico-printer and the cotton-dyer. (See SCARLET and TIN MORDANTS.) A compound of tin with gold, gives the fine crimson and purple colours to stained glass and artificial gems. (See PURPLE OF CASSIUS.) Enamel is made by fusing oxide of tin with the materials of flint glass. This oxide is also an ingredient in the white and yellow glazes of pottery-ware.

An ACCOUNT of TIN coined in Cornwall and Devon, from 1817 to 1829 inclusive:--

+------+-------+---------+ |Years.|Blocks.|Tons. | +------+-------+---------+ | 1817 | 25,379|4,120 | | 1818 | 23,048|3,745-1/3| | 1819 | 18,881|3,065 | | 1820 | 17,084|2,773-1/2| | 1821 | 19,273|3,128 | | 1822 | 18,732|3,137 | | 1823 | 24,077|4,031 | | 1824 | 28,602|4,819 | | 1825 | 24,902|4,170 | | 1826 | 26,299|4,406 | | 1827 | 31,744|5,316 | | 1828 | 28,179|4,696 | | 1829 | 26,344|4,396 | +------+-------+---------+

+---------------------+-------------+ | Tin imported. |Tin exported.| |Duty, 50_s._ per cwt.| | +-------+-------------+-------------+ | | _Cwts._ | _Cwts._ | | 1827 | 2,217 | 2,938 | | 1828 | 3,386 | 3,258 | | 1829 | 2,674 | 2,581 | | 1830 | 15,539 | 10,426 | | 1831 | 8,099 | 12,226 | | 1832 | 29,203 | 21,720 | | 1833 | 35,124 | 39,850 | | 1834 | 46,769 | 46,685 | | 1835 | 17,705 | 23,796 | | 1836 | 23,236 | 17,231 | +-------+-------------+-------------+

The principal importations are from the East India Company’s territories and Ceylon:--they amounted in 1832 to 24,585 cwts.; in 1833 to 27,928; in 1834 to 33,611; in 1835 to 10,104; and in 1836 to 17,729. From Sumatra and Java 1961 cwts. were imported in 1832, and 1145 in 1834, but in the other years greatly less.

Declared } | | | | value of } 1827. | 1829. | 1831. | 1833. | 1835. tin and }302,255_l._|235,178_l._|239,143_l._|282,176_l._|381,076_l._ pewter } | | | | wares and } | | | | tin-plates} 1828. | 1830. | 1832. | 1834. | 1836. exported }266,651_l._|249,657_l._|243,259_l._|337,056_l._|387,951_l._ in } | | | |

Of these goods, from two-fifths to three-fifths go to the United States of America.

ABSTRACT of TIN coined in Cornwall and Devon, in the year ending June 30, 1835; from the _Mining Review_, vol. iii.

+---------------------------+-----------+-------------+------------+ | |Blocks of | Blocks of | | | |Grain Tin. | Common Tin. | Totals. | | Smelters. +-----+-----+------+------+------+-----+ | |1834.|1835.|1834. |1835. |1834. |1835.| +---------------------------+-----+-----+------+------+------+-----+ |Daubuz and Co. | 728 | 875 | 6114 | 4494 | 6842 | 5369| |Grenfell and Boase | 344 | 196 | 3776 | 3097 | 4120 | 3293| |Bolitho and Sons | 229 | 153 | 3829 | 3099 | 4058 | 3252| |R. and J. Michell | 101 | 75 | 709 | 575 | 810 | 650| |Wheal Vor Adventurers | -- | -- | 3925 | 4069 | 3925 | 4069| |Taylor, Sons and Co. | -- | 112 | -- | 1250 | -- | 1362| |John Batten and Son | 28 | 49 | 2352 | 2351 | 2380 | 2400| |Joseph Carne | -- | -- | 896 | 851 | 896 | 851| |William Cornish | -- | -- | 622 | 574 | 622 | 574| |Gill and Co. (at Morwelham)| -- | -- | 758 | -- | 758 | --| | Ditto (at Calstock) | 60 | -- | 605 | -- | 665 | --| |Rundle, Paul and Co. | -- | 12 | -- | 1545 | -- | 1557| | +-----+-----+------+------+------+-----+ | Total |1490 |1472 |23586 |21905 |25076 |23377| +---------------------------+-----+-----+------+------+------+-----+

Total, in 1834, 4180 tons; in 1835, 3899 tons. (6 blocks = 1 ton.)

TINCAL, crude borax.

TINCTORIAL MATTER. One of the most curious and valuable facts ascertained upon this subject, is, that madder kept in casks, in a warm place, undergoes a species of fermentation, which, by ripening or rather deoxidizing the colouring-matter, increases its dyeing power by no less than from 20 to 50 per cent. See M. H. Schlumberger’s memoir read to the _Société Industrielle de Mulhausen_, 24 November, 1837.

TINCTURE is a title used by apothecaries to designate alcohol, in a somewhat dilute state, impregnated with the active principles of either vegetable or animal substances.

TIN-GLASS, is a name of bismuth.

TIN MORDANTS, for dyeing scarlet:--

_Mordant_ A, as commonly made by the dyers, is composed of 8 parts of aquafortis, 1 part of common salt or sal ammoniac, and 1 of granulated tin. This preparation is very uncertain.

_Mordant_ B.--Pour into a glass globe with a long neck, 3 parts of pure nitric acid at 30° B.; and 1 part of muriatic acid at 17°; shake the globe gently, avoiding the corrosive vapours, and put a loose stopper in its mouth. Throw into this nitro-muriatic acid, one-eighth of its weight of pure tin, in small bits at a time. When the solution is complete, and settled, decant it into bottles, and close them with ground stoppers. It should be diluted only when about to be used.

_Mordant_ C, by Dambourney.--In two drams Fr. (144 grs.) of pure muriatic acid, dissolve 18 grains of Malacca tin. This is reckoned a good mordant for brightening or fixing the colour of peachwood.

_Mordant_ D, by Hellot.--Take 8 ounces of nitric acid, diluted with as much water; dissolve in it half an ounce of sal ammoniac, and 2 drams of nitre. In this acid solution dissolve one ounce of granulated tin of Cornwall, observing not to put in a fresh piece till the preceding be dissolved.

_Mordant_ E, by Scheffer.--Dissolve one part of tin in four of a nitro-muriatic acid, prepared with nitric acid diluted with its own weight of water, and one thirty-secondth of sal ammoniac.

_Mordant_ F, by Poërner.--Mix one pound of nitric acid with one pound of water, and dissolve in it an ounce and a half of sal ammoniac. Stir it well, and add, by very slow degrees, two ounces of tin turned into thin ribbons upon the lathe.

_Mordant_ G, by Berthollet.--Dissolve in nitric acid of 30° B., one-eighth of its weight of sal ammoniac, then add by degrees one-eighth of its weight of tin, and dilute the solution with one-fourth of its weight of water.

_Mordant_ K, by Dambourney.--In one dram (72 grs.) of muriatic acid at 17°, one of nitric acid at 30°, and 18 grains of water, dissolve, slowly and with some heat, 18 grains of fine Malacca tin.

_Mordant_ L, is the birch bark prescribed by Dambourney.--This bark, dried and ground, is said to be a very valuable substance for fixing the otherwise fugitive colours produced by woods, roots, archil, &c.

TIN-PLATE. The only alloy of iron interesting to the arts, is that with tin, in the formation of _tin-plate_, or _white-iron_.

The sheet iron intended for this manufacture is refined with charcoal instead of coke, subsequently rolled to various degrees of thinness, and cut into rectangles of different sizes, by means of a shearing-machine driven by a water-wheel, which will turn out 100 boxes a day, or four times the number cut by hand labour. The first step towards tinning, is to free the metallic surface from every particle of oxide or impurity, for any such would inevitably prevent the iron from alloying with the tin. The plates are next bent separately by hand into a saddle or Λ shape, and ranged in a reverberatory oven, so that the flame may play freely among them, and heat them to redness. They are then plunged into a bath, composed of four pounds of muriatic acid diluted with three gallons of water, for a few minutes, taken out and drained on the floor, and once more exposed to ignition in a furnace, whereby they are _scaled_, that is to say, cast their scales. The above bath will suffice for scaling 1800 plates. When taken out, they are beat level and smooth on a cast-iron block, after which they appear mottled blue and white, if the _scaling_ has been thoroughly done. They are next passed through _chilled_ rolls or cast-iron cylinders, rendered very hard by being cast in thick iron moulds, as has been long practised by the Scotch founders in casting bushes for cart-wheels. After this process of _cold rolling_, the plates are immersed, for ten or twelve hours, in an acidulous lye, made by fermenting bran-water, taking care to set them separately on edge, and to turn them at least once, so that each may receive a due share of the operation. From this lye-steep they are transferred into a leaden trough, divided by partitions, and charged with dilute sulphuric acid. Each compartment is called a _hole_ by the workmen, and is calculated to receive about 225 plates, the number afterwards packed up together in a _box_. In this liquid they are agitated about an hour, till they become perfectly bright, and free from such black spots as might stain their surface at the time of immersion. This process, called pickling, is both delicate and disagreeable, requiring a good workman, at high wages. The temperature of the two last steeps should be at least 90° or 100° F., which is kept up by stoves in the apartments. The plates are finally scoured with hemp and sand in a body of water, and then put aside for use in a vessel of pure water, under which they remain bright and free from rust for many months, a very remarkable circumstance.

The _tinning_ follows these preparatory steps. A range of rectangular cast-iron pots is set over a fire-flue in an apartment called the _stow_, the workmen stationing themselves opposite to the narrow ends. The first rectangle in the range is the tin-pot; the second is the wash-pot, with a partition in it; the third is the grease-pot; the fourth is the pan, grated at bottom; the fifth is the list-pot, and is greatly narrower than any of the rest: they are all of the same length.

The prepared plates, dried by rubbing bran upon them, are first immersed one by one in a pot filled with melted tallow alone, and are left there for nearly an hour. They are thence removed, with the adhering grease, into pot No. 1., filled with a melted mixture of block and grain tin, covered with about four inches of tallow, slightly carbonized. This pot is heated by a fire, playing under its bottom and round its sides, till the metal becomes so hot as nearly to inflame the grease. Here about 340 plates are exposed, upright, to the action of the tin for an hour and a half, or more, according to their thickness. They are next lifted out, and placed upon an iron grating, to let the superfluous metal drain off; but this is more completely removed in the next process, called _washing_.

Into the wash-pot, No. 2., filled with melted _grain_ tin, the workman puts the above plates, where the heat detaches the ribs, and drops. There is a longitudinal partition in it, for keeping the drop of tin that rises in washing from entering the vessel where the last dip is given. Indeed, the metal in the wash-pot, after having acted on 60 or 70 boxes, becomes so foul, that the weight of a block (300 cwt.) of it, is transferred into the tin-pot, No. 1., and replaced by a fresh block of grain tin. The plates being lifted out of the wash-pot, with tongs held in the left hand of the workman, are scrubbed on each side with a peculiar hempen brush, held in his right hand, then dipped for a moment in the hot tin, and forthwith immersed in the adjoining grease-pot, No. 3. This requires manual dexterity; and though only three-pence be paid for brushing and tin-washing 225 plates, yet a good workman can earn six shillings and three-pence in twelve hours, by putting 5625 plates through his hands. The final tin-dip is useful to remove the marks of the brush, and to make the surface uniformly bright. To regulate the temperature of the tallow-pot, and time during which the plates are left in it, requires great skill and circumspection on the part of the workman. If kept in it too long, they would be deprived to a certain extent of their silvery lustre; and if too short, streaks of tin would disfigure their surface. As a thick plate retains more heat after being lifted out of the washing-pot, it requires a proportionally cooler grease-pot. This pot has pins fixed within it, to keep the plates asunder; and whenever the workman has transferred five plates to it, a boy lifts the first out into the cold adjoining pan, No. 4.; as soon as the workman transfers a sixth plate, the boy removes the second; and so on. The manufacture is completed by removing the wire of tin left on the under edge of the plates, in consequence of their vertical position in the preceding operations. This is the business of the _list-boy_, who seizes the plates when they are cool enough to handle, and puts the lower edge of each, one by one, into the list-pot, No. 5., which contains a very little melted tin, not exceeding a quarter of an inch in depth. When he observes the wire-edge to be melted, he takes out the plate, and, striking it smartly with a thin stick, detaches the superfluous metal, which leaves merely a faint stripe where it lay. This mark may be perceived on every tin-plate in the market.

The plates are finally prepared for packing up in their boxes, by being well cleansed from the tallow, by friction with bran.

Mr. Thomas Morgan obtained a patent, in September, 1829, for clearing the sheet-iron plates with dilute sulphuric acid in a _hole_, instead of _scaling_ them in the usual way, previous to their being cold rolled, annealed, and tinned; whereby, he says, a better article is produced at a cheaper rate.

_Crystallized tin-plate_, see MOIRÉE METALLIQUE. It would seem that the acid merely lays bare the crystalline structure really present on every sheet, but masked by a film of redundant tin. Though this showy article has become of late years vulgarized by its cheapness, it is still interesting in the eyes of the practical chemist. The English tin-plates marked F, answer well for producing the _Moirée_, by the following process. Place the tin-plate, slightly heated, over a tub of water, and rub its surface with a sponge dipped in a liquor composed of four parts of aquafortis, and two of distilled water, holding one part of common salt or sal ammoniac in solution. Whenever the crystalline spangles seem to be thoroughly brought out, the plate must be immersed in water, washed either with a feather or a little cotton (taking care not to rub off the film of tin that forms the feathering), forthwith dried with a low heat, and coated with a lacquer varnish, otherwise it loses its lustre in the air. If the whole surface is not plunged at once in cold water, but if it be partially cooled by sprinkling water on it, the crystallization will be finely variegated with large and small figures. Similar results will be obtained by blowing cold air through a pipe on the tinned surface, while it is just passing from the fused to the solid state; or a variety of delineations may be traced, by playing over the surface of the plate with the pointed flame of a blowpipe.

The following TABLE shows the several sizes of tin-plates, the marks by which they are distinguished, and their current wholesale prices in London:--

+------------------+---------+----+------+--------+----------------+ |Names. |Sizes. |No. |Weight|Marks |Prices per | | | |in a|of |on the |box, in | | | |box.|each |boxes. +--------+-------+ | | | |box. | | 1823. | 1838. | +------------------+---------+----+------+--------+--------+-------+ | |_Inches._| |c q l| |_s._ |_s. d._| |Common, No. 1. |13-3/4 by| | | | | | | |10 | 225|1 0 0|CI. |47 | 35 | | Ditto 2. |13-1/4 --| | | | | | | | 9-1/4 | |0 3 21|CII. |45 | 33 6 | | Ditto 3. |12-3/4 --| | | | | | | | 9-1/2 | |0 3 16|CIII. |43 | 32 9 | |Cross, No. 1. |13-3/4 --| | | | | | | |10 | |1 1 0|XI. |53 | 40 2 | |Two crosses, 1. | | |1 1 21|XXI. |58 | 43 2 | |Three crosses, 1. | | |1 2 14|XXX. I. |63 | 47 | |Four crosses, 1. | | |1 3 7|XXXX. I.| | | |Common doubles |16-3/4 --| | | | | | | |12-1/2 | 100|0 3 21|CD. |64-6} | 48 6 | |Cross doubles | | |1 0 14|XD. |73-6}[A]| 56 | |Two cross do. | | |1 1 7|XXD. |81 } | 60 6 | |Three cross do. | | |1 2 0|XXXD. |88-6} | 65 | |Four cross do. | | |1 2 21|XXXXD. | | | |Com. small doubles| 5 -- 11| 200|1 2 0|CSD. |69 | 51 6 | |Cross do. do. | | |1 2 21|XSD. |75 | 56 0 | |Two cross do. | | |1 3 14|XXSD. |80 | 59 6 | |Three do. do. | | |2 0 7|XXXSD. | | | |Four do. do. | | |2 1 0|XXXXSD. | | | |Waster’s com. | 3-3/4 --| | | | | | |No. 1. |10 | 225|1 0 0|WCI. |44 | 32 9 | |Ditto cross, 1.| ditto | |1 1 0|WXI. |50 | 47 3 | +------------------+---------+----+------+--------+--------+-------+

c = _cwt._ q = _qrs._ l = _lbs._ [A] = 150 sheets in each.

These are the cash prices of one wholesale warehouse in Thames-street; an immediately adjoining warehouse charges fully 1_s._ more upon the standard CI, and proportionally upon the others.

TITANIUM, is a rare metal, discovered by Klaproth, in menachanite, in 1794. It has been detected since in the form of small cubes of a copper-red colour, in some of the blast furnaces in Yorkshire. According to Hassenfratz, its presence in small quantity does not impair the malleability of iron. It is very brittle, so hard as to scratch steel, and very light, having a specific gravity of only 5·3. It will not melt in the heat of any furnace, nor dissolve, when crystallized, even in nitro-muriatic acid; but only when in fine powder. By calcination with nitre, it becomes oxygenated, and forms titanate of potassa. Traces of this metal may be detected in many irons, both wrought and cast. The principal ores of titanium are _sphene_, common and foliated, _rutile_, _iserine_, _menachanite_, and _octahedrite_ or _pyramidal titanium ore_. None of them has been hitherto applied to any use.

TOBACCO. It is said that the name tobacco was given by the Spaniards to the plant, because it was first observed by them at Tabasco, or Tabaco, a province of Yucatan in Mexico. In 1560, Nicot, the French ambassador to Portugal, having received some tobacco from a Flemish merchant, showed it, on his arrival in Lisbon, to the grand prior, and, on his return into France, to Catherine of Medicis, whence it has been called Nicotiana by the botanists. Admiral Sir Francis Drake having, on his way home from the Spanish Main, in 1586, touched at Virginia, and brought away some forlorn colonists, is reported to have first imported tobacco into England. But, according to Lobel, this plant was cultivated in Britain before the year 1570; and was consumed by smoking in pipes by Sir Walter Raleigh, and companions, so early as the year 1584.

The plants are hung up to dry during four or five weeks; taken down out of the sheds in damp weather, for in dry they would be apt to crumble into pieces; stratified in heaps, covered up, and left to sweat for a week or two, according to their quality and the state of the season; during which time they must be examined frequently, opened up, and turned over, lest they become too hot, take fire, or run into putrefactive fermentation. This process needs to be conducted by skilful and attentive operatives. An experienced negro can form a sufficiently accurate judgment of the temperature, by thrusting his hand down into the heap.

The tobacco thus prepared, or often without fermentation, is sent into the market; but, before being sold, it must undergo the inspection of officers, appointed by the state with very liberal salaries, who determine its quality, and brand an appropriate stamp upon its casks, if it be sound; but if it be bad, it is burned.

Our respectable tobacconists are very careful to separate all the damaged leaves, before they proceed to their preparation, which they do by spreading them in a heap upon a stone pavement, watering each layer in succession, with a solution of sea salt, of spec. grav. 1·107, called _sauce_, till a ton or more be laid; and leaving their principles to react on each other for three or four days, according to the temperature, and the nature of the tobacco. It is highly probable that ammonia is the volatilizing agent of many odours, and especially of those of tobacco and musk. If a fresh green leaf of tobacco be crushed between the fingers, it emits merely the herbaceous smell common to many plants; but if it be triturated in a mortar, along with a little quicklime or caustic potash, it will immediately exhale the peculiar odour of snuff. Now analysis shows the presence of muriate of ammonia in this plant, and fermentation serves further to generate free ammonia in it; whence, by means of this process, and lime, the odoriferous vehicle is abundantly developed. If, on the other hand, the excess of alkaline matter in the tobacco of the shops be saturated by a mild dry acid, as the tartaric, its peculiar aroma will entirely disappear.

Tobacco contains a great quantity of an azotized principle, which by fermentation produces abundance of ammonia; the first portions of which saturate the acid juices of the plant, and the rest serve to volatilize its odorous principles. The salt water is useful chiefly in moderating the fermentation, and preventing it from passing into the putrefactive stage; just as salt is sometimes added to saccharine worts in tropical countries, to temper the fermentative action. The sea salt, or concentrated sea water, which contains some muriate of lime, tends to keep the tobacco moist, and is therefore preferable to pure chloride of sodium for this purpose. Some tobacconists mix molasses with the salt _sauce_, and ascribe to this addition the violet colour of the _macouba_ snuff of Martinique; and others add a solution of extract of liquorice. The following prescription is that used by a skilful manufacturer:--In a solution of the liquorice juice, a few figs are to be boiled for a couple of hours; to the decoction, while hot, a few bruised anise-seeds are to be added, and when cold, common salt to saturation. A little silent spirit of wine being poured in, the mixture is to be equably, but sparingly, sprinkled with the rose of a watering-pot, over the leaves of the tobacco, as they are successively stratified upon the preparation floor.

The fermented leaves, being next stripped of their middle ribs by the hands of children, are sorted anew, and the large ones are set apart for making cigars. Most of the tobaccos on sale in our shops are mixtures of different growths: one kind of smoking tobacco, for example, consists of 70 parts of Maryland, and 30 of meagre Virginia; and one kind of snuff consists of 80 parts of Virginia, and 30 parts of either Humesfort or Warwick. The Maryland is a very light tobacco, in thin yellow leaves; that of Virginia is in large brown leaves, unctuous or somewhat gluey on the surface, having a smell somewhat like the figs of Malaga; that of Havannah is in brownish, light leaves, of an agreeable and rather spicy smell; it forms the best cigars. The Carolina tobacco is less unctuous than the Virginian; but in the United States it ranks next to the Maryland.

The shag tobacco is dried to the proper point upon sheets of copper.

Tobacco is cut into what is called shag tobacco by knife-edged chopping stamps, a machine somewhat similar to that represented under METALLURGY, _fig._ 670. For grinding the tobacco leaves into snuff, conical mortars are employed, somewhat like that used by the Hindoos for grinding sugar-canes, _fig._ 1080.; but the sides of the snuff-mill have sharp ridges from the top to near the bottom.

Mr. L. W. Wright obtained a patent in August, 1827, for a tobacco-cutting machine, which bears a close resemblance to the well-known machines with revolving knives, for cutting straw into chaff. The tobacco, after being squeezed into cakes, is placed upon a smooth bed within a horizontal trough, and pressed by a follower and screws to keep it compact. These cakes are progressively advanced upon the bed, or fed in, to meet the revolving blades. The speed of the feeding-screw determines the degree of fineness of the sections or particles into which the tobacco is cut.

I was employed some years ago by the Excise, to analyze a quantity of snuff, seized on suspicion of having been adulterated by the manufacturer. I found it to be largely drugged with pearl-ashes, and to be thereby rendered very pungent, and absorbent of moisture; an economical method of rendering an effete article at the same time active and aqueous.

According to the recent analysis of Possett and Reimann, 10,000 parts of tobacco-leaves contain--6 of the peculiar chemical principle _nicotine_; 1 of _nicotianine_; 287 of slightly bitter extractive; 174 of gum, mixed with a little malic acid; 26·7 of a green resin; 26 of vegetable albumen; 104·8 of a substance analogous to gluten; 51 of malic acid; 12 of malate of ammonia; 4·8 of sulphate of potassa; 6·3 of chloride of potassium; 9·5 of potassa, which had been combined with malic and nitric acids; 16·6 of phosphate of lime; 24·2 of lime, which had been combined with malic acid; 8·8 of silica; 496·9 of fibrous or ligneous matter; traces of starch; and 88·28 of water.

_Nicotine_ is a transparent colourless liquid, of an alkaline nature. It may be distilled in a retort plunged into a bath heated to 290° Fahrenheit. It has a pricking, burning taste, which is very durable; and a pungent disagreeable smell. It burns by means of a wick, with the diffusion of a vivid light, and much smoke. It may be mixed with water in all proportions. It is soluble also in acetic acid, oil of almonds, alcohol, and ether, but not in oil of turpentine. It acts upon the animal economy with extreme violence; and in the dose of one drop it kills a dog. It forms salts with the acids. About one part of it may be obtained by very skilful treatment from one thousand of good tobacco.

Tobacco imported into the United Kingdom, viz.--unmanufactured, in 1836, 52,232,907 lbs.; in 1837, 27,070,448 lbs.;--manufactured, and snuff, in 1836, 182,248 lbs.; in 1837, 642,287 lbs. Retained for home consumption, unmanufactured, in 1836, 22,309,021 lbs.; in 1837, 22,504,343 lbs.:--manufactured, and snuff, in 1836, 159,226 lbs.; in 1837, 145,045 lbs. Duty received,--on unmanufactured tobacco, in 1836, _£_3,344,703; in 1837, _£_3,375,125; on manufactured tobacco, and snuff, in 1836, £71,560; in 1837, _£_65,220.

TOBACCO-PIPES. The practice of smoking tobacco has become so general in many nations as to render the manufacture of tobacco-pipes a considerable branch of industry. Some seek in the inhalation of tobacco-smoke a pleasurable narcotism; others imagine it to be beneficial to their health; but, in general, smoking is merely a dreamy resource against ennui, which ere long becomes an indispensable stimulus. The filthiness of this habit, the offensive odour which persons under its influence emit from their mouths and clothes, the stupor it too often occasions, as well as the sallow complexion, black or carious teeth, and impaired digestion, all prove the great consumption of tobacco to be akin in evil influence upon mankind to the use of ardent spirits.

Tobacco-pipes are made of a fine-grained plastic white clay, to which they have given the name. It is worked with water into a thin paste, which is allowed to settle in pits, or it may be passed through a sieve, to separate the siliceous or other stony impurities; the water is afterwards evaporated till the clay becomes of a doughy consistence, when it must be well kneaded to make it uniform. Pipe-clay is found chiefly in the isle of Purbeck and Dorsetshire. It is distinguished by its perfectly white colour, and its great adhesion to the tongue after it is baked; owing to the large proportion of alumina which it contains.

A child fashions a ball of clay from the heap, rolls it out into a slender cylinder upon a plank, with the palms of his hands, in order to form the stem of the pipe. He sticks a small lump to the end of the cylinder for forming the bowl; which having done, he lays the pieces aside for a day or two, to get more consistence. In proportion as he makes these rough figures, he arranges them by dozens on a board, and hands them to the pipemaker.

The pipe is finished by means of a folding brass or iron mould, channelled inside of the shape of the stem and the bowl, and capable of being opened at the two ends. It is formed of two pieces, each hollowed out like a half-pipe, cut as it were lengthwise; and these two jaws, when brought together, constitute the exact space for making one pipe. There are small pins in one side of the mould, corresponding to holes in the other, which serve as guides for applying the two together with precision.

The workman takes a long iron wire, with its end oiled, and pushes it through the soft clay in the direction of the stem, to form the bore, and he directs the wire by feeling with his left hand the progress of its point. He lays the pipe in the groove of one of the jaws of the mould, with the wire sticking in it; applies the other jaw, brings them smartly together, and unites them by a clamp or vice, which produces the external form. A lever is now brought down, which presses an oiled stopper into the bowl of the pipe, while it is in the mould, forcing it sufficiently down to form the cavity; the wire being meanwhile thrust backwards and forwards so as to pierce the tube completely through. The wire must become visible at the bottom of the bowl, otherwise the pipe will be imperfect. The wire is now withdrawn, the jaws of the mould opened, the pipe taken out, and the redundant clay removed with a knife. After drying for a day or two, the pipes are scraped, polished with a piece of hard wood, and the stems being bent into the desired form, they are carried to the baking kiln, which is capable of firing fifty gross in from 8 to 12 hours. A workman and a child can easily make five gross of pipes in a day.

No tobacco-pipes are so highly prized as those made in Natolia, in Turkey, out of meerschaum, a somewhat plastic magnesian stone, of a soft greasy feel, which is formed into pipes after having been softened with water. It becomes white and hard in the kiln.

A tobacco-pipe kiln should diffuse an equal heat to every part of its interior, while it excludes the smoke of the fire. The crucible, or large sagger, A, A, _figs._ 1155. and 1156., is a cylinder, covered in with a dome. It is placed over the fireplace B, and enclosed within a furnace of ordinary brickwork D, D, lined with fire-bricks E, E. Between this lining and the cylinder, a space of about 4 inches all round is left for the circulation of the flame. There are 12 supports or ribs between the cylinder and the furnace lining, which form so many flues, indicated by the dotted lines _x_, in _fig._ 1156. (the dotted circle representing the cylinder). These ribs are perforated with occasional apertures, as shown in _fig._ 1155., for the purpose of connecting the adjoining flues; but the main bearing of the hollow cylinder is given by five piers, _b_, _b_, _c_, formed of bricks projecting over and beyond each other. One of these piers _c_, is placed at the back of the fireplace, and the other four at the sides _b_, _b_. These project nearly into the centre, in order to support and strengthen the bottom; while the flues pass up between them, unite at the top of the cylinder in the dome L, and discharge the smoke by the chimney N.

The lining F, E, E, of the chimney is open on one side to form the door, by which the cylinder is charged and discharged. The opening is permanently closed as high as _k_, _fig._ 1155., by an iron plate plastered over with fire-clay; above this it is left open, and shut merely with temporary brickwork while the furnace is going. When this is removed, the furnace can be filled or emptied through the opening, the cylindric crucible having a correspondent aperture in its side, which is closed in the following ingenious way, while the furnace is in action. The workman first spreads a layer of clay round the edge of the opening, he then sticks the stems of broken pipes across from one side to the other, and plasters up the interstices with clay, exactly like the lath-and-plaster work of a ceiling. The whole of the cylinder, indeed, is constructed in this manner, the bottom being composed of a great many fragments of pipe stems, radiating to the centre; these are coated at the circumference with a layer of clay. A number of bowls of broken pipes are inserted in the clay; in these other fragments are placed upright to form the sides of the cylinder. The ribs round the outside, which form the flues, are made in the same way, as well as the dome L; by which means the cylindric case may be made very strong, and yet so thin as to require little clay in the building, a moderate fire to heat it, while it is not apt to split asunder. The pipes are arranged within, as shown in the figure, with their bowls resting against the circumference and their ends supported on circular pieces of clay _r_, which are set up in the centre for that purpose. Six small ribs are made to project inwards all round the crucible, at the proper heights, to support the different ranges of pipes, without having so many resting on each other as to endanger their being crushed by the weight. By this mode of distribution, the furnace may contain 50 gross, or 7200 pipes, all baked within 8 or 9 hours; the fire being gradually raised, or damped if occasion be, by a plate partially slid over the chimney top.

TODDY, _Sura_, _Mee-ra_, sweet juice.--The proprietors of coco-nut plantations in the peninsula of India, and in the Island of Ceylon, instead of collecting a crop of nuts, frequently reap the produce of the trees by extracting sweet juice from the flower-stalk. When the flowering branch is half shot, the toddy-drawers bind the stock round with a young coco-nut leaf in several places, and beat the spadix with a short baton of ebony. This beating is repeated daily for ten or twelve days, and about the end of that period a portion of the flower-stalk is cut off. The stump then begins to bleed, and an earthen vessel (chatty) or a calabash is suspended under it, to receive the juice, which is by the Europeans called _toddy_.

A thin slice is taken from the stump daily, and the toddy is removed twice a day. A coco-nut frequently pushes out a new _spadix_ once a month; and after each spadix begins to bleed, it continues to produce freely for a month, by which time another is ready to supply its place. The old spadix continues to give a little juice for another month, after which it withers; so that there are sometimes two pots attached to a tree at one time, but never more. Each of these spadices, if allowed to grow, would produce a bunch of nuts from two to twenty. Trees in a good soil produce twelve bunches in the year; but when less favourably situated, they often do not give more than six bunches. The quantity of six English pints of toddy is sometimes yielded by a tree daily.

Toddy is much in demand as a beverage in the neighbourhood of villages, especially where European troops are stationed. When it is drunk before sunrise, it is a cool, delicious, and particularly wholesome beverage; but by eight or nine o’clock fermentation has made some progress, and it is then highly intoxicating.[68]

[68] Contributions to the History of the Coco-nut Tree. By Henry Marshall, Esq., Deputy Inspector of Hospitals.

TOLU, is a brownish-red balsam, extracted from the stem of the _Myroxilon toluiferum_, a tree which grows in South America. It is composed of resin, oil, and benzoic acid. Having an agreeable odour, it is sometimes used in perfumery. It has a place in the Materia Medica, but for what good reason I know not.

TOMBAC, is a white alloy of copper.

TONKA BEAN, the fruit of the _Dipterix odorata_, affords a concrete crystalline volatile oil (_stearoptène_), called _coumarine_ by the French. It is extracted by digestion with alcohol, which dissolves the stearoptène, and leaves a fat oil. It has an agreeable smell, and a warm taste. It is fusible at 122° Fahrenheit, and volatile at higher heats.

TOPAZ. See LAPIDARY.

TORTOISE-SHELL, or rather scales, a horny substance, that covers the hard strong covering of a bony contexture, which encloses the _Testudo imbricata_, Linn. The lamellæ or plates of this tortoise are 13 in number, and may be readily separated from the bony part by placing fire beneath the shell, whereby they start asunder. They vary in thickness from one-eighth to one-quarter of an inch, according to the age and size of the animal, and weigh from 5 to 25 pounds. The larger the animal, the better is the shell. This substance may be softened by the heat of boiling water; and if compressed in this state by screws in iron or brass moulds, it may be bent into any shape. The moulds being then plunged in cold water, the shell becomes fixed in the form imparted by the mould. If the turnings or filings of tortoise-shell be subjected skilfully to gradually increased compression between moulds immersed in boiling water, compact objects of any desired ornamental figure or device may be produced. The soldering of two pieces of scale is easily effected, by placing their edges together, after they are nicely filed to one bevel, and then squeezing them strongly between the long flat jaws of hot iron pincers, made somewhat like a hairdresser’s curling-tongs. The pincers should be strong, thick, and just hot enough to brown paper slightly, without burning it. They may be soldered also by the heat of boiling water, applied along with skilful pressure. But in whatever way this process is attempted, the surfaces to be united should be made very smooth, level, and clean; the least foulness, even the touch of a finger, or breathing upon them, would prevent their coalescence. See HORN.

TOUCH-NEEDLES, and TOUCH-STONE, are means of ascertaining the quality of gold trinkets. See ASSAY.

TOW. See FLAX.

TRAGACANTH, GUM. (_Gomme adracante_, Fr.; _Traganth_, Germ.) See GUM.

TRAVERTINO. See TUFA.

TREACLE, is the viscid brown uncrystallizable syrup which drains from the sugar-refining moulds. Its specific gravity is generally 1·4, and it contains upon an average 75 per cent. of solid matter, by my experiments.

TRIPOLI (_Terre pourrie_, Fr.; _Tripel_, Germ.); rotten-stone; is a mineral of an earthy fracture, a yellowish-gray or white colour, composition impalpably fine, meagre to the touch, does not adhere to the tongue, and burns white. Its analogue, the _Polierschiefer_, occurs in thin flat foliated pieces, of the above colours, occasionally striped; soft, absorbent of water; spec. grav. 1·9. to 2·2.

M. Ehrenberg has shown that both of these friable homogeneous rocks, which consist almost entirely of silica, are actually composed of the exuviæ or rather the skeletons of infusoria (_animalcula_) of the family of _Barcillariæ_, and the genera _Cocconema_, _Gonphonema_, &c. They are recognised with such distinctness in the microscope, that their analogies with living species may be readily traced; and in many cases there are no appreciable differences between the living and the petrified. The species are distinguished by the number of partitions or transverse lines upon their bodies. The length is about 1/288 of a line. M. Ehrenberg made his observations upon the tripolis of Billen in Bohemia of Santafiora in Tuscany, of the Isle of France, and of Francisbad, near Eger.

The meadow iron ore (_Fer limoneux des marais_) is composed almost wholly of the _Gaellonella ferruginea_. Most of these infusoria are lacustrine; but others are marine, particularly the _tripolis_ of the Isle of France.

According to the chemical analysis of Bucholz, tripoli consists of--silica, 81; alumina, 1·5; oxide of iron, 8; sulphuric acid, 3·45; water, 4·55. This specimen was probably found in a coal-field. The tripoli of Corfu is reckoned the best for scouring or brightening brass and other metals. Mr. Phillips found in the Derbyshire rotten-stone (near Bakewell), 86 of alumina, 4 of silica, and 10 of carbon--being a remarkable difference in composition from the Bohemian.

TUFA, or TUF, is a gray deposit of calcareous carbonate, from springs and streams.

TULA METAL, is an alloy of silver, copper, and lead.

TUNGSTEN (Eng. and Fr.; _Wolfram_, Germ.); is a peculiar metal, which occurs in the state of an acid (the _tungstic_), combined with various bases, as with lime, the oxides of iron, manganese, and lead. The metal is obtained by reduction of the ore, or the deoxidizement of the acid, in the form of a dark steel-gray powder, which assumes under the burnisher a feeble metallic lustre. Its specific gravity is 17·22.

TURBITH MINERAL, is the yellow subsulphate of mercury.

TURF (_Peat_, Scotch; _Tourbe_, Fr.; _Torf_, Germ.); consists of vegetable matter, chiefly of the moss family, in a state of partial decomposition by the action of water. Cut, during summer, into brick-shaped pieces, and dried, it is extensively used as fuel by the peasantry in every region where it abounds. The dense black turf, which forms the lower stratum of a peat-moss, is much contaminated with iron, sulphur, sand, &c., while the lighter turf of the upper strata, though nearly pure vegetable matter, is too bulky for transportation, and too porous for factory fuel. These defects have been happily removed by Mr. Williams, managing director of the Dublin Steam Navigation Company, who has recently obtained a patent for a method of converting the lightest and purest beds of peat-moss, or bog, into the four following products: 1. A brown combustible solid, denser than oak; 2. A charcoal, twice as compact as that of hard wood; 3. A factitious coal; and 4. A factitious coke; each of which possesses very valuable properties.

Mr. D’Ernst, artificer of fire-works to Vauxhall, has proved, by the severe test of coloured fires, that the turf charcoal of Mr. Williams is 20 per cent. more combustible than that of oak. Mr. Oldham, engineer of the Bank of England, has applied it in softening his steel plates and dies, with remarkable success. But one of the most important results of Mr. Williams’s invention is, that with 10 cwts. of pitcoal, and 2-1/2 cwts. of his factitious coal, the same steam power is now obtained, in navigating the Company’s ships, as with 17-1/2 cwts. of pitcoal alone; thereby saving 30 per cent. in the stowage of fuel. What a prospect is thus opened up of turning to admirable account the unprofitable bogs of Ireland; and of producing, from their inexhaustible stores, a superior fuel for every purpose of arts and engineering.

The turf is treated as follows:--Immediately after being dug, it is triturated under revolving edge-wheels, faced with iron plates perforated all over their surface, and is forced by the pressure through these apertures, till it becomes a species of pap, which is freed from the greater part of its moisture by squeezing in a hydraulic press between layers of caya cloth, then dried, and coked in suitable ovens.--(See CHARCOAL, and PITCOAL, COKING OF.) Mr. Williams makes his factitious coal by incorporating with pitch or rosin, melted in a cauldron, as much of the above charcoal, ground to powder, as will form a doughy mass, which is moulded into bricks in its hot and plastic state. From the experiments of M. Le Sage, detailed in the 5th volume of “The Repertory of Arts,” charred ordinary turf seems to be capable of producing a far more intense heat than common charcoal. It has been found preferable to all other fuel for case-hardening iron, tempering steel, forging horseshoes, and welding gun-barrels. Since turf is partially carbonized in its native state, when it is condensed by the hydraulic press, and fully charred, it must evidently afford a charcoal very superior in calorific power to the porous substance generated from wood by fire.

TURKEY RED, is a brilliant dye produced on cotton goods by MADDER.

TURMERIC, _Curcuma_, _Terra merita_, (_Souchet_, or _Safran des Indes_, Fr.; _Gelbwurzel_, Germ.); is the root of the _Curcuma longa_ and _rotunda_, a plant which grows in the East Indies, where it is much employed in dyeing yellow, as also as a condiment in curry sauce or powder. The root is knotty, tubercular, oblong, and wrinkled; pale-yellow without, and brown-yellow within; of a peculiar smell, a taste bitterish and somewhat spicy. It contains a peculiar yellow principle, called _curcumine_, a brown, colouring-matter, a volatile oil, starch, &c. The yellow tint of turmeric is changed to brown-red by alkalis, alkaline earths, subacetate of lead, and several metallic oxides; for which reason, paper stained with it is employed as a chemical test.

Turmeric is employed by the wool-dyers for compound colours which require an admixture of yellow, as for cheap browns and olives. As a yellow dye, it is employed only upon silk. It is a very fugitive colour. A yellow lake may be made by boiling turmeric powder with a solution of alum, and pouring the filtered decoction upon pounded chalk.

TURNSOLE. See ARCHIL and LITMUS.

TURQUOIS. See LAPIDARY.

TURPENTINE (_Térébinthine_, Fr.; _Terpenthin_, Germ.); is a substance which flows out of incisions made in the stems of several species of pines. It has the consistence and gray-yellow colour of honey. It has a smell which is not disagreeable to many persons, a warm, sharp, bitterish taste; dries into a solid in the air, with the evaporation of its volatile oil. It becomes quite fluid at a moderate elevation of temperature, and burns at a higher heat, with a bright but very fuliginous flame. There are several varieties of turpentine.

1. _Common turpentine_, is extracted from incisions in the _Pinus abies_ and _Pinus silvestris_. It has little smell; but a bitter burning taste. It consists of the volatile oil of turpentine to the amount of from 5 to 25 per cent.; and of rosin or colophony.

2. _Venice turpentine_, is extracted from the _Pinus larix_ (larch), and the French turpentine from the _Pinus maritima_. The first comes from Styria, Hungary, the Tyrol, and Switzerland, and contains from 18 to 25 per cent. of oil; the second, from the south of France, and contains no more than 12 per cent. of oil. The oil of all the turpentines is extracted by distilling them along with water. They dissolve in all proportions in alcohol, without leaving any residuum. They also combine with alkaline lyes, and in general with the salifiable bases. Venice turpentine contains also succinic acid.

3. Turpentine of Strasbourg is extracted from the _Pinus picea_ and _Abies excelsa_. It affords 33·5 per cent. of volatile oil, and some volatile or crystallizable resin, with extractive matter and succinic acid.

4. Turpentine of the Carpathian mountains, and of Hungary; the first of which comes from the _Pinus cembra_, and the second from the _Pinus mugos_. They resemble that of Strasbourg.

5. Turpentine of Canada, called Canada balsam, is extracted from the _Pinus canadensis_ and _balsamea_. Its smell is much more agreeable than that of the preceding species.

6. Turpentine of Cyprus or Chio, is extracted from the _Pistacea terebinthus_. It has a yellow, greenish, or blue-green colour. Its smell is more agreeable, and taste less acrid, than those of the preceding sorts.

Common Turpentine imported into the United Kingdom, in 1836, 370,981 cwts. 1 qr. 26 lbs.; in 1837, 415,023 cwts. 1 qr. 10 lbs. Retained for home consumption, in 1836, 341,693 cwts. 18 lbs.; in 1837, 405,772 cwts. 2 qrs. 14 lbs. Duty received, in 1836, _£_74,052; in 1837, _£_87,918.

TURPENTINE, OIL OF, sometimes called essence of turpentine. As found in commerce, it contains more or less rosin, from which it may be freed by re-distillation along with water. It is colourless, limpid, very fluid, and possessed of a very peculiar smell. Its specific gravity, when pure, is 0·870; that of the oil commonly sold in London, is 0·875. It always reddens litmus paper, from containing a little succinic acid. According to Oppermann, the oil which has been repeatedly rectified over chloride of calcium, consists of 84·60 carbon, 11·735 hydrogen, and 3·67 oxygen. When oil of turpentine contains a little alcohol, it burns with a clear flame; but otherwise it affords a very smoky flame. Chlorine inflames this oil; and muriatic acid converts it into a crystalline substance, like camphor. It is employed extensively in varnishes, paints, &c., as also in medicine.

TUTENAG, is an alloy of copper and zinc.

TYPE, (_Caractère_, Fr.; _Druckbuchstabe_, Germ.) The first care of the letter-cutter is to prepare well-tempered steel punches, upon which he draws or marks the exact shape of the letter, with pen and ink if it be large, but with a smooth blunted point of a needle if it be small; and then, with a proper sized and shaped graver and sculpter, he digs or scoops out the metal between the strokes upon the face of the punch, leaving the marks untouched and prominent. He next works the outside with files till it be fit for the matrix. Punches are also made by hammering down the hollows, filing up the edges, and then hardening the soft steel. Before he proceeds to sink and justify the matrix, he provides a mould to justify them by, of which a good figure is shown in plate XV., _Miscellany_, _figs._ 2. 3. of _Rees’s Cyclopædia_.

A matrix is a piece of brass or copper, about an inch and a half long, and thick in proportion to the size of the letter which it is to contain. In this metal the face of the letter intended to be cast is sunk, by striking it with the punch to a depth of about one eighth of an inch. The mould, _fig._ 1157., in which the types are cast, is composed of two parts. The outer part is made of wood, the inner of steel. At the top it has a hopper-mouth _a_, into which the fused type-metal is poured. The interior cavity is as uniform as if it had been hollowed out of a single piece of steel; because each half, which forms two of the four sides of the letter, is exactly fitted to the other. The matrix is placed at the bottom of the mould, directly under the centre of the orifice, and is held in its position by a spring _b_. Every letter that is cast can be loosened from the matrix only by removing the pressure on the spring.

A good type-foundry is always provided with several furnaces, each surmounted with an iron pot containing the melted alloy, of 3 parts of lead and 1 of antimony. Into this pot the founder dips the very small iron ladle, to lift merely as much metal as will cast a single letter at a time. Having poured in the metal with his right hand, and returned the ladle to the melting-pot, the founder throws up his left hand, which holds the mould, above his head, with a sudden jerk, supporting it with his right hand. It is this movement which forces the metal into all the interstices of the matrix; for without it, the metal, especially in the smaller moulds, would not be able to expel the air and reach the bottom. The pouring in the metal, the throwing up the mould, the unclosing it, removing the pressure of the spring, picking out the cast letter, closing the mould again, and re-applying the spring to be ready for a new operation, are all performed with such astonishing rapidity and precision, that a skilful workman will turn out 500 good letters in an hour, being at the rate of one every eighth part of a minute. A considerable piece of metal remains attached to the end of the type as it quits the mould. There are nicks upon the lower edge of the types, to enable the compositor to place them upright, without looking at them.

From the table of the _caster_, the heap of types turned out of his mould, is transferred from time to time to another table, by a boy, whose business it is to break off the superfluous metal, and that he does so rapidly as to clear from 2000 to 5000 types in an hour; a very remarkable dispatch, since he must seize them by their edges, and not by their feeble flat sides. From the breaking-off boy, the types are taken to the _rubber_, a man who sits in the centre of the workshop with a grit-stone slab on a table before him, and having on the fore and middle finger of his right hand a piece of tarred leather, passes each broad side of the type smartly over the stone, turning it in the movement, and that so dexterously, as to be able to rub 2000 types in an hour.

From the rubber, the types are conveyed to a boy, who, with equal rapidity sets them up in lines, in a long shallow frame, with their faces uppermost and nicks outwards. This frame, containing a full line, is put into the dresser’s hands, who polishes them on each side, and turning them with their faces downwards, cuts a groove or channel in their bottom, to make them stand steadily on end. It is essential that each letter be perfectly symmetrical and square; the least inequality of their length would prevent them from making a fair impression; and were there the least obliquity in their sides, it would be quite impossible, when 200,000 single letters are combined, as in one side of the _Times_ newspaper, that they could hold together as they require to do, when wedged up in the chases, as securely as if that side of type form a solid plate of metal. Each letter is finally tied up in lines of convenient length, the proportionate numbers of each variety, small letters, points, large capitals, small capitals, and figures, being selected, when the fount of type is ready for delivery to the printer.

The sizes of types cast in this country vary, from the smallest, called diamond, of which 205 lines are contained in a foot length, to those letters employed in placards, of which a single letter may be 3 or 4 inches high. The names of the different letters and their dimensions, or the number of lines which each occupies in a foot, are stated in the following table:--

Double Pica 41-1/2 Paragon 44-1/2 Great Primer 51-1/4 English 64 Pica 71-1/2 Small Pica 83 Long Primer 89 Bourgeois 102-1/4 Brevier 112-1/2 Minion 128 Nonpareil 143 Pearl 178 Diamond 205

T. Aspinwall, Esq., the American consul, obtained, in May, 1828, a patent for an improved method of casting printing types by means of a mechanical process, being a communication from a foreigner residing abroad. The machine is described, with six explanatory figures, in the second series of Newton’s Journal, vol. v. page 212. The patentee does not claim, as his invention, any of the parts separately, but the general process and arrangement of machinery; more particularly the manner of suspending a swing table (upon which the working parts are mounted) out of the horizontal and perpendicular position; the mode of moving the table with the parts of the mould towards the melting-pot; the manner of bringing the parts of the mould together, and keeping them closed during the operation of casting the types. Several other mechanical schemes have been proposed for founding types, but I have been informed by very competent judges, Messrs. Clowes, that none of them can compete in practical utility with that dexterity and precision of handiwork, which I have often seen practised in their great printing establishment in Stamford-street.

U.

ULTRAMARINE (_Outremer_, Fr.; _Ultramarins_, Germ.); is a beautiful blue pigment obtained from the variegated blue mineral, called lazulite (_lapis lazuli_), by the following process:--Grind the stone to fragments, rejecting all the colourless bits, calcine at a red heat, quench in water, and then grind to an impalpable powder along with water, in a paint-mill, (see PAINTS, GRINDING OF,) or with a porphyry slab and muller. The paste being dried, is to be rubbed to powder, and passed through a silk sieve. 100 parts of it are to be mixed with 40 of rosin, 20 of white wax, 25 of linseed oil, and 15 of Burgundy pitch, previously melted together. This resinous compound is to be poured hot into cold water; kneaded well first with two spatulas, then with the hands, and then formed into one or more small rolls. Some persons prescribe leaving these pieces in the water during 15 days, and then kneading them in it, whereby they give out the blue pigment, apparently because the ultramarine matter adheres less strongly than the _gangue_, or merely siliceous matter of the mineral, to the resinous paste. MM. Clement and Desormes, who were the first to divine the true nature of this pigment, think that the soda contained in the lazulite, uniting with the oil and the rosin, forms a species of soap, which serves to wash out the colouring-matter. If it should not separate readily, water heated to about 150° F. should be had recourse to. When the water is sufficiently charged with blue colour, it is poured off and replaced by fresh water; and the kneading and change of water are repeated till the whole of the colour is extracted. Others knead the mixed resinous mass under a slender stream of water, which runs off with the colour into a large earthen pan. The first waters afford, by rest, a deposit of the finest ultramarine; the second, a somewhat inferior article, and so on. Each must be washed afterwards with several more waters, before they acquire the highest quality of tone; then dried separately, and freed from any adhering particles of the pitchy compound by digestion in alcohol. The remainder of the mass being melted with oil, and kneaded in water containing a little soda or potash, yields an inferior pigment, called _ultramarine ashes_. The best _ultramarine_ is a splendid blue pigment, which works well with oil, and is not liable to change by time. Its price in Italy was five guineas the ounce, a few years ago, but it is now greatly reduced.

The blue colour of _lazulite_ had been always ascribed to iron, till MM. Clement and Desormes, by a most careful analysis, showed it to consist of--silica, 34; alumina, 33; sulphur, 3; soda, 22; and that the iron, carbonate of lime, &c. were accidental ingredients, essential neither to the mineral, nor to the pigment made from it. By another analyst, the constituents are said to be--silica, 44; alumina, 35; and soda, 21; and by a third, potassa was found instead of soda, showing shades of difference in the composition of the stone.

Till a few years ago, every attempt failed to make ultramarine artificially. At length, in 1828, M. Guimet resolved the problem, guided by the analysis of MM. Clement and Desormes, and by an observation of M. Tassaert, that a blue substance like ultramarine was occasionally produced on the sandstone hearths of his reverberatory soda furnaces. Of M. Guimet’s finest pigment I received a bottle several years ago, from my friend M. Merimée, secretary of the _Ecole de Beaux Arts_, which has been found by artists little, if any, inferior to the lazulite ultramarine. M. Guimet sells it at 60 francs per pound French,--which is little more than two guineas the English pound. He has kept his process secret. But M. Gmelin, of Tübingen, has published a prescription for making it; which consists in enclosing carefully in a Hessian crucible a mixture of 2 parts of sulphur, and 1 of dry carbonate of soda, heating them gradually to redness till the mass fuses, and then sprinkling into it by degrees another mixture, of silicate of soda, and aluminate of soda; the first containing 72 parts of silica, and the second 70 parts of alumina. The crucible must be exposed after this for an hour to the fire. The ultramarine will be formed by this time; only it contains a little sulphur, which can be separated by means of water. M. Persoz, professor of chemistry at Strasbourg, has likewise succeeded in making an ultramarine, of perhaps still better quality than that of M. Guimet. Lastly, M. Robiquet has announced, that it is easy to form ultramarine, by heating to redness a proper mixture of kaolin (China clay), sulphur, and carbonate of soda. It would therefore appear, from the preceding details, that ultramarine may be regarded as a compound of silicate of alumina, silicate of soda, with sulphuret of sodium; and that to the reaction of the last constituent upon the former two, it owes its colour.

UMBER, is a massive mineral; fracture large and flat; conchoidal in the great, very fine earthy in the small; dull; colour, liver, chestnut,--dark yellowish brown; opaque; does not soil, but writes; adheres strongly to the tongue, feels a little rough and meagre, and is very soft; specific gravity 2·2. It occurs in beds with brown jasper in the Island of Cyprus, and is used by painters as a brown colour, and to make varnish dry quickly.

URANIUM, is a rare metal, first discovered by Klaproth, in the black mineral called _pechblende_, found in a mine near Johann-Georgen-Stadt, in Saxony, and which is a sulphuret of uranium. A double phosphate of uranium and copper, called _green uranite_, and _uran mica_, occurs in Cornwall. It has been reduced to the metallic state by various devices, but it has hardly the appearance of metal to the naked eye, and from the rarity of its ores is not likely to be of any importance in the arts.

URAO, is the native name of a sesquicarbonate of soda found at the bottom of certain lakes in Mexico, especially to the north of Zacatecas, and in several other provinces; also in South America at Columbia, 48 English miles from Merida.

V.

VALONIA, is a kind of acorn, imported from the Levant and the Morea for the use of tanners, as the husk or cup contains abundance of tannin. The quantity imported for home consumption in 1836, was 80,511 cwts.; of which Turkey furnished 58,724, Italy and the Italian islands, 7209.

VANADIUM, is a metal discovered by Sefström, in 1830, in a Swedish iron, remarkable for its ductility, extracted from the iron mine of Jaberg, not far from Jönköping. Its name is derived from Vanadis, a Scandinavian idol. This metal has been found in the state of vanadic acid, in a lead ore from Zimapan, in Mexico. The finery cinders of the Jaberg iron contain more vanadium than the metal itself. It exists in it as vanadic acid. For the reduction of this acid to vanadium, see Berzelius’s _Traité de Chimie_, vol. iv. p. 644. Vanadium is white, and when its surface is polished, it resembles silver or molybdenum more than any other metal. It combines with oxygen into two oxides and an acid.

The vanadate of ammonia, mixed with infusion of nutgalls, forms a black liquid, which is the best writing-ink hitherto known. The quantity of the salt requisite is so small as to be of no importance when the vanadium comes to be more extensively extracted. The writing is perfectly black. The acids colour it blue, but do not remove it, as they do tannate of iron: the alkalis, diluted so far as not to injure the paper, do not dissolve it; and chlorine, which destroys the black colour, does not, however, make the traces illegible, even when they are subsequently washed with a stream of water. It is perfectly fluent, and, being a chemical solution, stands in want of no viscid gum to suspend the colour, like common ink. The influence of time upon it remains to be tried.

VANILLA, is the oblong narrow pod of the _Epidendron vanilla_, Linn., of the natural family _Orchideæ_, which grows in Mexico, Colombia, Peru, and on the banks of the Oronoco.

The best comes from the forests round the village of Zentila, in the intendancy of Oaxaca.

The vanilla plant is cultivated in Brazil, in the West Indies, and some other tropical countries, but does not produce fruit of such a delicious aroma as in Mexico. It clings like a parasite to the trunks of old trees, and sucks the moisture which their bark derives from the lichens, and other cryptogamia, but without drawing nourishment from the tree itself, like the ivy and misletoe. The fruit is subcylindric, about 8 inches long, one-celled, siliquose, and pulpy within. It should be gathered before it is fully ripe.

When about 12000 of these pods are collected, they are strung like a garland by their lower end, as near as possible to the foot-stalk; the whole are plunged for an instant in boiling water to blanch them; they are then hung up in the open air, and exposed to the sun for a few hours. Next day they are lightly smeared with oil, by means of a feather, or the fingers; and are surrounded with oiled cotton, to prevent the valves from opening. As they become dry, on inverting their upper end, they discharge a viscid liquid from it, and they are pressed at several times with oiled fingers to promote its flow. The dried pods lose their appearance, grow brown, wrinkled, soft, and shrink into one-fourth of their original size. In this state they are touched a second time with oil, but very sparingly; because, with too much oil, they would lose much of their delicious perfume. They are then packed for the market, in small bundles of 50 or 100 in each, enclosed in lead foil, or tight metallic cases. As it comes to us, vanilla is a capsular fruit, of the thickness of a swan’s quill, straight, cylindrical, but somewhat flattened, truncated at the top, thinned off at the ends, glistening, wrinkled, furrowed lengthwise, flexible, from 5 to 10 inches long, and of a reddish-brown colour. It contains a pulpy parenchyma, soft, unctuous, very brown, in which are imbedded black, brilliant, very small seeds. Its smell is ambrosiacal and aromatic; its taste hot, and rather sweetish. These properties seem to depend upon an essential oil, and also upon benzoic acid, which forms efflorescences upon the surface of the fruit. The pulpy part possesses alone the aromatic quality; the pericarpium has hardly any smell.

The kind most esteemed in France, is called _leq_ vanilla; it is about 6 inches long, from 1/4 to 1/3 of an inch broad, narrowed at the two ends, and curved at the base; somewhat soft and viscid, of a dark-reddish colour, and of a most delicious flavour, like that of balsam of Peru. It is called vanilla _givrées_, when it is covered with efflorescences of benzoic acid, after having been kept in a dry place, and in vessels not hermetically closed.

The second sort, called _vanilla simarona_, or bastard, is a little smaller than the preceding, of a less deep brown hue, drier, less aromatic, destitute of efflorescence. It is said to be the produce of the wild plant, and is brought from St. Domingo.

A third sort, which comes from Brazil, is the _vanillon_, or large vanilla of the French market; the _vanilla pamprona_ or _bova_ of the Spaniards. Its length is from 5 to 6 inches; its breadth from one-half to three-quarters of an inch. It is brown, soft, viscid, almost always open, of a strong smell, but less agreeable than the _leq_. It is sometimes a little spoiled by an incipient fermentation. It is cured with sugar, and enclosed in tin-plate boxes, which contain from 20 to 60 pods.

Vanilla, as an aromatic, is much sought after by makers of chocolate, ices, and creams; by confectioners, perfumers, and liquorists, or distillers. It is difficultly reduced to fine particles; but it may be sufficiently attenuated by cutting it into small bits, and grinding these along with sugar. The odorous principle can, for some purposes, be extracted by alcohol. Their analysis by Bucholz is unsatisfactory, and refers obviously to the coarsest sort. Berzelius says that the efflorescences are not acid.

VAPOUR (_Vapeur_, Fr.; _Dampf_, Germ.); is the state of elastic or aeriform fluidity into which any substance, naturally solid or liquid at ordinary temperatures, may be converted by the agency of heat. See EVAPORATION.

VARNISH. (_Vernis_, Fr.; _Firniss_, Germ.); is a solution of resinous matter, which is spread over the surface of any body, in order to give it a shining, transparent, and hard coat, capable of resisting, in a greater or less degree, the influences of air and moisture. Such a coat consists of the resinous parts of the solution, which remain in a thin layer upon the surface, after the liquid solvent has either evaporated away, or has dried up. When large quantities of spirit varnish are to be made, a common still, mounted with its capital and worm, is the vessel employed for containing the materials, and it is placed in a steam or water bath. The capital should be provided with a stuffing-box, through which a stirring-rod may pass down to the bottom of the still, with a cross-piece at its lower end, and a handle or winch at its top. After heating the bath till the alcohol boils and begins to distil, the heat ought to be lowered, that the solution may continue to proceed in an equable manner, with as little evaporation of spirit as possible. The operation may be supposed to be complete when the rod can be easily turned round. The varnish must be passed through a silk sieve of proper fineness; then filtered through porous paper, or allowed to clear leisurely in stone jars. The alcohol which has come over should be added to the varnish, if the just proportions of the resins have been introduced at first. The following are reckoned good French recipes for varnishes:--

_White spirit varnish._--Sandarach, 250 parts; mastic in tears, 64; elemi resin, 32; turpentine (Venice), 64; alcohol, of 85 per cent., 1000 parts by measure.

The turpentine is to be added after the resins are dissolved. This is a brilliant varnish, but not so hard as to bear polishing.

_Varnish for the wood toys of Spa._--Tender copal, 75 parts; mastic, 12·5; Venice turpentine, 6·5; alcohol, of 95 per cent., 100 parts by measure; water ounces, for example, if the other parts be taken in ounces.

The alcohol must be first made to act upon the copal, with the aid of a little oil of lavender or camphor, if thought fit; and the solution being passed through a linen cloth, the mastic must be introduced. After it is dissolved, the Venice turpentine, previously melted in a water-bath, should be added; the lower the temperature at which these operations are carried on, the more beautiful will the varnish be. This varnish ought to be very white, very drying, and capable of being smoothed with pumice-stone and polished.

_Varnish for certain parts of carriages._--Sandarach, 190 parts; pale shellac, 95; rosin, 125; turpentine, 190; alcohol, at 85 per cent., 1000 parts by measure.

_Varnish for cabinet-makers._--Pale shellac, 750 parts; mastic, 64; alcohol, of 90 per cent., 1000 parts by measure. The solution is made in the cold, with the aid of frequent stirring. It is always muddy, and is employed without being filtered.

With the same resins and proof spirit a varnish is made for the bookbinders to do over their morocco leather.

_The varnish of Watin, for gilded articles._--Gum lac, in grain, 125 parts; gamboge, 125; dragon’s blood, 125; annotto, 125; saffron, 32. Each resin must be dissolved in 1000 parts by measure, of alcohol of 90 per cent.; two separate tinctures must be made with the dragon’s blood and annotto, in 1000 parts of such alcohol; and a proper proportion of each should be added to the varnish, according to the shade of golden colour wanted.

For fixing engravings or lithographs upon wood, a varnish called _mordant_ is used in France, which differs from others chiefly in containing more Venice turpentine, to make it sticky; it consists of--sandarach, 250 parts; mastic in tears, 64; rosin, 125; Venice turpentine, 250; alcohol, 1000 parts by measure.

_Copal varnish._--Hard copal, 300 parts; drying linseed or nut oil, from 125 to 250 parts; oil of turpentine, 500; these three substances are to be put into three separate vessels; the copal is to be fused by a somewhat sudden application of heat; the drying oil is to be heated to a temperature a little under ebullition, and it is to be added by small portions at a time to the melted copal. When this combination is made, and the heat a little abated, the essence of turpentine, likewise previously heated, is to be introduced by degrees: some of the volatile oil will be dissipated at first; but more being added, the union will take place. Great care must be taken to prevent the turpentine vapour from catching fire, which might occasion serious accidents to the operator. When the varnish is made, and has cooled down to about the 130th degree of Fahr., it may be strained through a filter, to separate the impurities and undissolved copal.

Almost all varnish-makers think it indispensable to combine the drying oil with the copal, before adding the oil of turpentine; but in this they are mistaken. Boiling oil of turpentine combines very readily with fused copal; and, in some cases, it would probably be preferable to commence the operation with it, adding it in successive small quantities. Indeed, the whitest copal varnish can be made only in this way; for if the drying oil have been heated to nearly its boiling point, it becomes coloured, and darkens the varnish.

This varnish improves in clearness by keeping. Its consistence may be varied by varying the proportions of the ingredients, within moderate limits. Good varnish, applied in summer, should become so dry in 24 hours that the dust will not stick to it, nor receive an impression from the fingers. To render it sufficiently dry and hard for polishing, it must be subjected for several days to the heat of a stove.

_Milk of wax_, is a valuable varnish, which may be prepared as follows:--Melt in a porcelain capsule a certain quantity of white wax, and add to it, while in fusion, an equal quantity of spirit of wine, of sp. gr. 0·830; stir the mixture, and pour it upon a large porphyry slab. The granular mass is to be converted into a paste by the muller, with the addition, from time to time, of a little alcohol; and as soon as it appears to be smooth and homogeneous, water is to be introduced in small quantities successively, to the amount of four times the weight of the wax. This emulsion is to be then passed through canvas, in order to separate such particles as may be imperfectly incorporated.

The _milk of wax_, thus prepared, may be spread with a smooth brush upon the surface of a painting, allowed to dry, and then fused by passing a hot iron (salamander) over its surface. When cold, it is to be rubbed with a linen cloth to bring out the lustre. It is to the unchangeable quality of an encaustic of this nature, that the antient paintings upon the walls of Herculaneum and Pompeii owe their freshness at the present day.

The most recent practical account of the manufacture of varnishes, is that communicated by Mr. J. Wilson Neil to the Society of Arts, and published in the 49th volume of their “Transactions.”

The building or shed wherein varnish is made, ought to be quite detached from any buildings whatever, to avoid accidents by fire. For general purposes, a building about 18 feet by 16 is sufficiently large for manufacturing 4000 gallons and upwards annually, provided there are other convenient buildings for the purpose of holding the utensils, and warehousing the necessary stock.

Procure a copper pan, made like a common washing-copper, which will contain from fifty to eighty gallons, as occasion may require; when wanted, set it upon the boiling furnace, and fill it up with linseed oil within five inches of the brim. Kindle a fire in the furnace underneath, and manage the fire so that the oil shall gradually, but slowly, increase in heat for the first two hours; then increase the heat to a gentle simmer; and if there is any scum on the surface, skim it off with a copper ladle, and put the skimming away. Let the oil boil gently for three hours longer; then introduce, by a little at a time, one quarter of an ounce of the best calcined magnesia for every gallon of oil, occasionally stirring the oil from the bottom. When the magnesia is all in, let the oil boil rather smartly for one hour; it will then be sufficient. Lay a cover over the oil, to keep out the dust while the fire is withdrawn and extinguished by water; next uncover the oil, and leave it till next morning; and then, while it is yet hot, ladle it into the carrying-jack, or let it out through the pipe and cock; carry it away, and deposit it in either a tin or leaden cistern, for wooden vessels will not hold it; let it remain to settle for at least three months. The magnesia will absorb all the acid and mucilage from the oil, and fall to the bottom of the cistern, leaving the oil clear and transparent, and fit for use. Recollect, when the oil is taken out, not to disturb the bottoms, which are only fit for black paint.

GENERAL OBSERVATIONS AND PRECAUTIONS TO BE OBSERVED IN MAKING VARNISHES.

Set on the boiling-pot with 8 gallons of oil; kindle the fire; then lay the fire in the gum-furnace; have as many 8lb. bags of gum-copal all ready weighed up, as will be wanted; put one 8lb. into the pot, put fire to the furnace, set on the gum-pot; in three minutes (if the fire is brisk) the gum will begin to fuse and give out its gas, steam, and acid; stir and divide the gum, and attend to the rising of it, as before directed. 8lbs. of copal take in general from sixteen to twenty minutes in fusing, from the beginning till it gets clear like oil, but the time depends very much on the heat of the fire, and the attention of the operator. During the first twelve minutes, while the gum is fusing, the assistant must look to the oil, and bring it to a smart simmer; for it ought to be neither too hot, nor yet too cold, but in appearance beginning to boil, which he is strictly to observe, and, when ready, to call out, “Bear a hand!” Then immediately both lay hold of a handle of the boiling-pot, lift it right up, so as to clear the plate, carry it out and place it on the ash-bed, the maker instantly returning to the gum-pot, while the assistant puts three copper ladlefuls of oil into the copper pouring-jack, bringing it in and placing it on the iron plate at the back of the gum-pot to keep hot until wanted. When the maker finds the gum is nearly all completely fused, and that it will in a few minutes be ready for the oil, let him call out, “Ready oil!” The assistant is then to lift up the oil-jack with both hands, one under the bottom and the other on the handle, laying the spout over the edge of the pot, and wait until the maker calls out, “Oil!” The assistant is then to pour in the oil as before directed, and the boiling to be continued until the oil and gum become concentrated, and the mixture looks clear on the glass; the gum-pot is now to be set upon the brick-stand until the assistant puts three more ladlefuls of hot oil into the pouring-jack, and three more into a spare tin for the third run of gum. There will remain in the boiling-pot still 3-1/2 gallons of oil. Let the maker put his right hand down the handle of the gum-pot near to the side, with his left hand near the end of the handle, and with a firm grip lift the gum-pot, and deliberately lay the edge of the gum-pot over the edge of the boiling-pot until all its contents run into the boiling-pot. Let the gum-pot be held, with its bottom turned upwards, for a minute right over the boiling-pot. Observe, that whenever the maker is beginning to pour, the assistant stands ready with a thick piece of old carpet, without holes, and sufficiently large to cover the mouth of the boiling-pot should it catch fire during the pouring, which will sometimes happen if the gum-pot is very hot; should the gum-pot fire, it has only to be kept bottom upwards, and it will go out of itself; but if the boiling-pot should catch fire, during the pouring, let the assistant throw the piece of carpet quickly over the blazing pot, holding it down all round the edges; in a few minutes it will be smothered. The moment the maker has emptied the gum-pot, he throws into it half a gallon of turpentine, and with the _swish_ immediately washes it from top to bottom, and instantly empties it into the flat tin jack: he wipes the pot dry, and puts in 8lbs. more gum, and sets it upon the furnace; proceeding with this run exactly as with the last, and afterwards with the third run. There will then be 8 gallons of oil and 24lbs. of gum in the boiling-pot, under which keep up a brisk strong fire until a scum or froth rises and covers all the surface of the contents, when it will begin to rise rapidly. Observe, when it rises near the rivets of the handles, carry it from the fire, and set it on the ash-bed, stir it down again, and scatter in the driers by a little at a time; keep stirring, and if the frothy head goes down, put it upon the furnace, and introduce _gradually_ the remainder of the driers, always carrying out the pot when the froth rises near the rivets. In general, if the fire be good, all the time a pot requires to boil, from the time of the last gum being poured in, is about three and a half or four hours; but _time_ is no criterion for a beginner to judge by, as it may vary according to the weather, the quality of the oil, the quality of the gum, the driers, or the heat of the fire, &c.; therefore, about the third hour of boiling, try it on a bit of glass, and keep it boiling until it feels strong and stringy between the fingers; it is then boiled sufficiently to carry it on the ash-bed, and to be stirred down until it is cold enough to mix, which will depend much on the weather, varying from half an hour, in dry frosty weather, to one hour in warm summer weather. Previous to beginning to mix, have a sufficient quantity of turpentine ready, fill the pot, and pour in, stirring all the time at the top or surface, as before directed, until there are fifteen gallons, or five tins of oil of turpentine introduced, which will leave it quite thick enough if the gum is good, and has been well run; but if the gum was of a weak quality, and has not been well fused, there ought to be no more than twelve gallons of turpentine mixed, and even that may be too much. Therefore, when twelve gallons of turpentine have been introduced, have a flat saucer at hand, and pour into it a portion of the varnish, and in two or three minutes it will show whether it is too thick; if not sufficiently thin, add a little more turpentine, and strain it off quickly. As soon as the whole is stored away, pour in the turpentine washings, with which the gum-pots have been washed, into the boiling-pot, and with the swish quickly wash down all the varnish from the pot sides; afterwards, with a large piece of woollen rag dipped in pumice-powder, wash and polish every part of the inside of the boiling-pot, performing the same operation on the ladle and stirrers; rinse them with the turpentine washings, and at last rinse them altogether in clean turpentine, which also put to the washings; wipe dry with a clean soft rag the pot, ladle, stirrer, and funnels, and lay the sieve so as to be completely covered with turpentine, which will always keep it from gumming up. The foregoing directions concerning running the gum, and pouring in the oil, and also boiling off and mixing, are, with very little difference, to be observed in the making of all sorts of copal varnishes, except the differences of the quantities of oil, gum, &c., which will be found under the various descriptions by name, which will be hereafter described.

The choice of linseed oil is of peculiar consequence to the varnish-maker. Oil from fine full-grown ripe seed, when viewed in a phial, will appear limpid, pale, and brilliant; it is mellow and sweet to the taste, has very little smell, is specifically lighter than impure oil, and, when clarified, dries quickly and firmly, and does not materially change the colour of the varnish when made, but appears limpid and brilliant.

_Copal varnishes for fine paintings, &c._--Fuse 8 lbs. of the very cleanest pale African gum copal, and, when completely run fluid, pour in two gallons of hot oil, old measure; let it boil until it will string very strong; and in about fifteen minutes, or while it is yet very hot, pour in three gallons of turpentine, old measure, and got from the top of a cistern. Perhaps during the mixing, a considerable quantity of the turpentine will escape; but the varnish will be so much the brighter, transparent, and fluid; and will work freer, dry more quickly, and be very solid and durable when dry. After the varnish has been strained, if it is found too thick, before it is quite cold, heat as much turpentine, and mix with it, as will bring it to a proper consistence.

_Cabinet varnish._--Fuse 7 lbs. of very fine African gum copal, and pour in half a gallon of pale clarified oil; in three or four minutes after, if it feel stringy, take it out of doors, or into another building where there is no fire, and mix with it three gallons of turpentine; afterwards strain it, and put it aside for use. This, if properly boiled, will dry in ten minutes; but if too strongly boiled, will not mix at all with the turpentine; and _sometimes_, when boiled with the turpentine, will mix, and yet refuse to incorporate with any other varnish less boiled than itself: therefore it requires a nicety which is only to be learned from practice. This varnish is chiefly intended for the use of japanners, cabinet-painters, coach-painters, &c.

_Best body copal varnish for coach-makers, &c._--This is intended for the body parts of coaches and other similar vehicles, intended for polishing.

Fuse 8 lbs. of fine African gum copal; add two gallons of clarified oil (old measure); boil it very slowly for four or five hours, until quite stringy; mix with three gallons and a half of turpentine; strain off, and pour it into a cistern. As they are too slow in drying, coach-makers, painters, and varnish-makers, have introduced to two pots of the preceding varnish, one made as follows:--

8 lbs. of fine pale gum animé; 2 gallons of clarified oil; 3-1/2 gallons of turpentine. To be boiled four hours.

_Quick drying body copal varnish, for coaches, &c._

(1.) 8 lbs. of the best African copal 2 gallons of clarified oil; 1/2 lb. of dried sugar of lead; 3-1/2 gallons of turpentine. Boiled till stringy, and mixed and strained.

(2.) 8 lbs. of fine gum animé; 2 gallons of clarified oil; 1/4 lb. of white copperas; 3-1/2 gallons of turpentine. Boiled as before.

To be mixed and strained while hot into the other pot. These two pots mixed together will dry in six hours in winter, and in four in summer; it is very useful for varnishing old work on dark colours, &c.

_Best pale carriage varnish._

(1.) 8 lbs. 2d sorted African copal; 2-1/2 gallons of clarified oil. Boiled till very stringy. 1/4 lb. of dried copperas; 1/4 lb. of litharge; 5-1/2 gallons of turpentine. Strained, &c.

(2.) 8 lbs. of 2d sorted gum animé; 2-1/2 gallons of clarified oil; 1/4 lb. of dried sugar of lead; 1/4 lb. of litharge; 5-1/2 gallons of turpentine. Mix this to the first while hot.

This varnish will dry hard, if well boiled, in four hours in summer, and in six in winter. As the name denotes, it is intended for the varnishing of the wheels, springs, and carriage parts of coaches, chaises, &c.; also, it is that description of varnish which is generally sold to and used by house-painters, decorators, &c., as from its drying quality and strong gloss, it suits their general purposes well.

_Second carriage varnish._

8 lbs. of 2d sorted gum animé; 2-3/4 gallons of fine clarified oil; 5-1/4 gallons of turpentine; 1/4 lb. of litharge; 1/4 lb. of dried sugar of lead; 1/4 lb. of dried copperas. Boiled and mixed as before.

_Wainscot varnish._

8 lbs. of 2d sorted gum animé; 3 gallons of clarified oil; 1/4 lb. of litharge; 1/4 lb. of dried sugar of lead; 5-1/2 gallons of turpentine. To be well boiled until it strings very strong, and then mixed and strained.

Mahogany varnish is made either with the same proportions, with a little darker gum; otherwise it is wainscot varnish, with a small portion of gold size.

_Black japan_, is made by putting into the set-pot 48 pounds of Naples, or any other of the foreign asphaltums (except the Egyptian). As soon as it is melted, pour in 10 gallons of raw linseed oil; keep a moderate fire, and fuse 8 pounds of dark gum animé in the gum-pot; mix it with 2 gallons of hot oil, and pour it into the set-pot. Afterwards fuse 10 pounds of dark or sea amber in the 10 gallon iron pot; keep stirring it while fusing; and whenever it appears to be overheated, and rising too high in the pot, lift it from the fire for a few minutes. When it appears completely fused, mix in 2 gallons of hot oil, and pour the mixture into the set-pot; continue the boiling for 3 hours longer, and during that time introduce the same quantity of driers as before directed: draw out the fire, and let it remain until morning; then boil it until it rolls hard, as before directed: leave it to cool, and afterwards mix with turpentine.

_Pale amber varnish._--Fuse 6 pounds of fine picked, very pale transparent amber in the gum-pot, and pour in 2 gallons of hot clarified oil. Boil it until it strings very strong. Mix with 4 gallons of turpentine. This will be as fine as body copal, will work very free, and flow well upon any work it is applied to: it becomes very hard, and is the most durable of all varnishes; it is very excellent to mix in copal varnishes, to give them a hard and durable quality. Observe; amber varnish will always require a long time before it is ready for polishing.

_Best Brunswick black._--In an iron pot, over a slow fire, boil 45 pounds of foreign asphaltum for at least 6 hours; and during the same time boil in another iron pot 6 gallons of oil which has been previously boiled. During the boiling of the 6 gallons, introduce 6 pounds of litharge gradually, and boil until it feels stringy between the fingers; then ladle or pour it into the pot containing the boiling asphaltum. Let the mixture boil until, upon trial, it will roll into hard pills; then let it cool, and mix it with 25 gallons of turpentine, or until it is of a proper consistence.

_Iron-work black._--Put 48 pounds of foreign asphaltum into an iron pot, and boil for 4 hours. During the first 2 hours, introduce 7 pounds of red lead, 7 pounds of litharge, 3 pounds of dried copperas, and 10 gallons of boiled oil; add 1 eight-pound run of dark gum, with 2 gallons of hot oil. After pouring the oil and gum, continue the boiling 2 hours, or until it will roll into hard pills like japan. When cool, thin it off with 30 gallons of turpentine, or until it is of a proper consistence. This varnish is intended for blacking the iron-work of coaches and other carriages, &c.

_A cheap Brunswick black._--Put 28 pounds of common black pitch, and 28 pounds of common asphaltum made from gas tar, into an iron pot; boil both for 8 or 10 hours, which will evaporate the gas and moisture; let it stand all night, and early next morning, as soon as it boils, put in 8 gallons of boiled oil; then introduce, gradually, 10 pounds of red lead, and 10 pounds of litharge, and boil for 3 hours, or until it will roll very hard. When ready for mixing, introduce 20 gallons of turpentine, or more, until of a proper consistence. This is intended for engineers, founders, ironmongers, &c.; it will dry in half an hour, or less, if properly boiled.

_Axioms observed in the making of copal varnishes._--The more minutely the gum is run, or fused, the greater the quantity, and the stronger the produce. The more regular and longer the boiling of the oil and gum together is continued, the more fluid or free the varnish will extend on whatever it is applied to. When the mixture of oil and gum is too suddenly brought to string by too strong a heat, the varnish requires more than its just proportion of turpentine to thin it, whereby its oily and gummy quality is reduced, which renders it less durable; neither will it flow so well in laying on. The greater proportion of oil there is used in varnishes, the less they are liable to crack, because the tougher and softer they are. By increasing the proportion of gum in varnishes, the thicker will be the stratum, the firmer they will set solid, and the quicker they will dry. When varnishes are quite new made, and must be sent out for use before they are of sufficient age, they must always be left thicker than if they were to be kept the proper time. Varnish made from African copal alone possesses the most elasticity and transparency. Too much driers in varnish render it opaque and unfit for delicate colours. Copperas does not combine with varnish, but only hardens it. Sugar of lead does combine with varnish. Turpentine improves by age; and varnish by being kept in a warm place. All copal or oil varnishes require age before they are used.

_Concluding observations._--All body varnishes are intended and ought to have 1-1/2 lbs. of gum to each gallon of varnish, when the varnish is strained off, and cold; but as the _thinning up_, or quantity of turpentine required to bring it to its proper consistence, depends very much upon the degree of boiling the varnish has undergone, therefore, when the gum and oil have not been strongly boiled, it requires less turpentine for that purpose; whereas, when the gum and oil are very strongly boiled together, a pot of 20 gallons will require perhaps 3 gallons above the regular proportionate quantity; and if mixing the turpentine is commenced too soon, and the pot not sufficiently cool, there will be frequently above a gallon and a half of turpentine lost by evaporation.

All carriage, wainscot, and mahogany varnish ought to have fully 1 pound of gum for each gallon, when strained and cold; and should one pot require more than its proportion of turpentine, the following pot can easily be left not quite so strongly boiled; then it will require less turpentine to thin it up.

Gold sizes, whether pale or dark, ought to have fully half a pound of good gum copal to each gallon, when it is finished; and the best black japan, to have half a pound of good gum, or upwards, besides the quantity of asphaltum.

_Fine mastic, or picture varnish._--Put 5 pounds of fine picked gum mastic into a new 4-gallon tin bottle; get ready 2 pounds of glass, bruised as small as barley; wash it several times; afterwards dry it perfectly, and put it into the bottle with 2 gallons of turpentine that has settled some time; put a piece of soft leather under the bung; lay the tin on a sack upon the counter, table, or any thing that stands solid; begin to agitate the tin, smartly rolling it backward and forward, causing the gum, glass, and turpentine, to work as if in a barrel-churn for at least 4 hours, when the varnish may be emptied out into any thing sufficiently clean, and large enough to hold it. If the gum is not all dissolved, return the whole into the bottle, and agitate as before, until all the gum is dissolved; then strain it through fine thin muslin into a clean tin bottle: leave it uncorked, so that the air can get in, but no dust; let it stand for 9 months, at least, before it is used; for the longer it is kept, the tougher it will be, and less liable to chill or bloom. To prevent mastic varnish from chilling, boil 1 quart of river sand with 2 ounces of pearl-ashes; afterwards wash the sand three or four times with hot water, straining it each time; put the sand on a soup-plate to dry, in an oven; and when it is of a good heat, pour half a pint of hot sand into each gallon of varnish, and shake it well for 5 minutes; it will soon settle, and carry down the moisture of the gum and turpentine, which is the general cause of mastic varnish chilling on paintings.

_Common mastic varnish._--Put as much gum mastic, unpicked, into the gum-pot as may be required, and to every 2-3/4 pounds of gum pour in 1 gallon of cold turpentine; set the pot over a very moderate fire, and stir it with the stirrer; be careful, when the steam of the turpentine rises near the mouth of the pot, to cover it with the carpet, and carry it out of doors, as the vapour is very apt to catch fire. A few minutes’ low heat will perfectly dissolve 8 pounds of gum, which will, with 4 gallons of turpentine, produce, when strained, 4-1/2 gallons of varnish; to which add, while yet hot, 5 pints of pale turpentine varnish, which improves the body and hardness of the mastic varnish.

_Crystal varnish_, may be made either in the varnish-house, drawing-room, or parlour. Procure a bottle of Canada balsam, which can be had at any druggist’s; draw out the cork, and set the bottle of balsam at a little distance from the fire, turning it round several times, until the heat has thinned it; then have something that will hold as much as double the quantity of balsam; carry the balsam from the fire, and, while fluid, mix it with the same quantity of good turpentine, and shake them together until they are well incorporated: in a few days the varnish is fit for use, particularly if it is poured into a half-gallon glass or stone bottle, and kept in a gentle warmth. This varnish is used for maps, prints, charts, drawings, paper ornaments, &c.; and when made upon a larger scale, requires only warming the balsam to mix with the turpentine.

_White hard spirit-of-wine varnish._--Put 5 pounds of gum sandarac into a 4-gallon tin bottle, with 2 gallons of spirits of wine, 60 over proof, and agitate it until dissolved, exactly as directed for the best mastic varnish, recollecting, if washed glass is used, that it is convenient to dip the bottle containing the gum and spirits into a copperful of hot water every 10 minutes--the bottle to be immersed only 2 minutes at a time--which will greatly assist the dissolving of the gum; but, above all, be careful to keep a firm hold over the cork of the bottle, otherwise the rarefaction will drive the cork out with the force of a shot, and perhaps set fire to the place. The bottle, every time it is heated, ought to be carried away from the fire; the cork should be eased a little, to allow the rarefied air to escape; then driven tight, and the agitation continued in this manner until all the gum is properly dissolved; which is easily known by having an empty tin can to pour the varnish into, until near the last, which is to be poured into a gallon measure. If the gum is not all dissolved, return the whole into the 4-gallon tin, and continue the agitation until it is ready to be strained, when every thing ought to be quite ready, and perfectly clean and dry, as oily tins, funnels, strainers, or any thing damp, or even cold weather, will chill and spoil the varnish. After it is strained off, put into the varnish 1 quart of very pale turpentine varnish, and shake and mix the two well together. Spirit varnishes should be kept well corked: they are fit to use the day after being made.

_Brown hard spirit varnish_--is made by putting into a bottle 3 pounds of gum sandarac, with 2 pounds of shellac, and 2 gallons of spirits of wine, 60 over proof; proceeding exactly as before directed for the white hard varnish, and agitating it when cold, which requires about 4 hours’ time, without any danger of fire; whereas, making any spirit varnish by heat is always attended with danger. No spirit varnish ought to be made either near a fire or by candle light. When this brown hard is strained, add 1 quart of turpentine varnish, and shake and mix it well: next day it is fit for use.

The _Chinese varnish_, comes from a tree, which grows in Cochin-China, China, and Siam. It forms the best of all varnishes.

_Gold lacker._--Put into a clean 4-gallon tin, 1 pound of ground turmeric, 1-1/2 ounces of powdered gamboge, 3-1/2 pounds of powdered gum sandarac, 3/4 of a pound of shellac, and 2 gallons of spirits of wine. After being agitated, dissolved, and strained, add 1 pint of turpentine varnish, well mixed.

_Red spirit lacker._

2 gallons of spirits of wine; 1 pound of dragon’s blood; 3 pounds of Spanish annotto; 3-1/4 pounds of gum sandarac; 2 pints of turpentine. Made exactly as the yellow gold lacker.

_Pale brass lacker._

2 gallons of spirits of wine; 3 ounces of Cape aloes, cut small; 1 pound of fine pale shellac; 1 ounce gamboge, cut small. No turpentine varnish. Made exactly as before.

But observe, that those who make lackers, frequently want some paler, and some darker, and sometimes inclining more to the particular tint of certain of the component ingredients. Therefore, if a 4-ounce phial of a strong solution of each ingredient be prepared, a lacker of any tint can be produced at any time.

_Preparation of linseed oil for making varnishes._--Put 25 gallons of linseed oil into an iron or copper pot that will hold at least 30 gallons; put a fire under, and gradually increase the heat, so that the oil may only simmer, for 2 hours; during that time the greatest part of its moisture evaporates; if any scum arises on the surface, skim it off, and put that aside for inferior purposes. Then increase the gradually, and sprinkle in, by a little at a time, 3 lbs. of scale litharge, 3 lbs. of good red lead, and 2 lbs. of Turkey umber, all well dried and free from moisture. If any moist driers are added, they will cause the oil to tumefy; and, at the same time, darken it, causing it to look opaque and thick, ropy and clammy, and hindering it from drying and hardening in proper time; besides, it will lie on the working painting like a piece of bladder skin, and be very apt to rise in blisters. As soon as all the driers are added to the oil, keep quietly stirring the driers from the bottom of the pot; otherwise they will burn, which will cause the oil to blacken and thicken before it is boiled enough. Let the fire be so regulated that the oil shall only boil slowly for three hours from the time all the driers were added; if it then ceases to throw up any scum, and emits little or no smoke, it is necessary to test its temperature by a few quill tops or feathers. Dip a quill top in the oil every two minutes, for when the oil is boiled enough, the quill top will crackle or curl up quite burnt; if so, draw out the fire immediately, and let the oil remain in the pot at least from 10 to 24 hours, or longer if convenient, for the driers settle much sooner when the oil is left to cool in the pot, than when it is immediately taken out.

_Poppy oil._--Into four pints of pure soft water, put two ounces of foreign white vitriol; warm the water in a clean copper pan, or glazed earthen jar, until the vitriol is dissolved; pour the mixture into a clean glass or stone bottle, large enough to contain three gallons; then add to the solution of vitriol one gallon and a half of poppy oil, cork and agitate the bottle regularly and smartly for at least two hours; then pour out the contents into a wide earthenware dish: leave it at rest for eight days, when the oil will be clean and brilliant on the surface, and may be taken off with a spoon or flat skimmer, and put up in a glass bottle and exposed to the light, which in a few weeks renders the oil exceedingly limpid and colourless.

_Nut-oil, or oil of walnuts_, is extracted by expression; and that which is extracted without heat, is certainly the most pale, pure, and nutritive seasoning, and retains an exquisite taste of the fruit. That designed for the arts is of inferior quality, and is plentifully imported to us from France; the heat it undergoes in its torrefaction, previous to its expression, disposes it to dry more quickly than that expressed by the cold process; but, at the same time, the heat, though it frees it from its unctuous quality, gives it more colour. When it has been extracted by the cold process, it may be prepared in the same way as directed for the poppy oil.

In the above article I have retained the workmen’s names--gum, white vitriol, &c., instead of resin, sulphate of zinc, &c.

VEINS (_Filons_, Fr.; _Gänge_, Germ.); are the fissures or rents in rocks, which are filled with peculiar mineral substances, most commonly metallic ores.

VEIN STONES, or GANGUES, are the mineral substances which accompany, and frequently enclose, the metallic ores.

VELLUM, is a fine sort of PARCHMENT, which see.

VELVET (_Velours_, Fr.; _Sammet_, Germ.); a peculiar stuff, the nature of which is explained under FUSTIAN and TEXTILE FABRICS.

VENETIAN CHALK, is STEATITE.

VENUS, is the mythological name of copper.

VENTILATION, or the renewal of fresh air in stagnant places, is nowhere exhibited to such advantage as in the coal mines of Northumberland and Durham, where Mr. Buddle has carried well nigh to systematic perfection the plan of coursing the air through the winding galleries, originally contrived about the year 1760, by Mr. James Spedding, of Workington, the ablest pitman of his day.[69] He converted the whole of the passages into air-pipes, so to speak, drew the current of air from the downcast pit, then traversed it up and down, and round about, through the several sheths of the workings, so that no particular gallery was left without a current of air. He thereby succeeded in actually expelling the noxious gases from the mines; those demons, which in Germany, at no remote era, were wont to be combated by the priests with impotent exorcisms or pious frauds. Before Mr. Buddle introduced his improvements, he has known the air to be led through a series of workings, thirty miles long, before it made its exit. There is in every coal mine an experienced corps, called wastemen, because they travel over the waste, or the exhausted regions, who can tell at once, by the whistling sound which the air makes at the crevices in certain partitions and doors, whether the ventilation be in good condition or not. They hear these stoppings begin to _sing_ or _call_, as they say, whenever an interruption takes place in any point of the labyrinthian line. Another indication of something being wrong, is when the doors get so heavy, that the boys in attendance upon them find them difficult to shut or open. The instant such a defect is discovered by any one, he cries aloud, “Holloa, there is something wrong--the doors are calling!”

[69] Mining engineers use the term _good pitman_, as admirals do _good seaman_, to denote a proficient in his calling.

In Mr. Spedding’s system, the whole of the return air came in one current to his rarefying furnace (see letter C, _fig._ 1158.), whether it was at the explosive point or not. This distribution was often fraught with such danger, that a torrent of water had to be kept in readiness, under the name of the waterfall, to be let down to extinguish the fire in a moment. Many explosions at that time occurred, from the furnaces below, and also down through tubes from the furnaces above-ground.

About the year 1807, Mr. Buddle had his attention intensely occupied with this most important object, and then devised his plan of a divided current, carrying that portion through the active furnace C, _fig._ 1158., and the portion of the air from the _foul_ workings of the air which, descending in the downcast pit A, coursed through the _clean_ workings, up the dumb furnace D, till it reached a certain elevation in B, the upcast pit, above the fireplace. The pitmen had a great aversion, however, at first, to adopt this plan, as they thought that the current of air, by being split, would lose its ventilating power; but they were, ere long, convinced by Mr. Buddle to the contrary. He divides the main current into two separate streams, at the bottom of the pit A, as shown by darts in the figure; the feathered ones, representing that part of the pit in which the course of the current of air is free from explosive mixture, or does not contain above one-thirtieth of carburetted hydrogen, as indicated by its effect upon the flame of a candle. The naked darts denote the portions of the mine where the air, being charged to the firing point, is led off towards D, the dumb furnace, which communicates with the hot upcast shaft, out of reach of the flame, and thence derives its power of draught. By suitable alterations in the stoppings (see the various transverse lines, and the crosses), any portion of the workings may, by the agency of the furnace, be laid out of, or brought within, the course of the vitiated current, at the pleasure of the skilful mine-viewer; so that, if he found it necessary, he could confine, by proper arrangements of his furnace, all the vitiated current to a mere gas-pipe or drift, and direct it wholly through the dumb furnace. During a practice of twenty years, Mr. Buddle has not met with any accident in consequence of a defect in the stoppings preventing the complete division of the air. The engineer has it thus within his power to detach or insulate those portions of the mine in which there is a great exudation of gas, from the rest; and, indeed, he is continually making changes, borrowing and lending currents, so to speak; sometimes laying one division or panel upon the one air-course, and sometimes upon the other, just to suit the immediate emergency. As soon as any district has ceased to be dangerous, by the exhaustion of the gas-blowers, it is transferred from the foul to the pure air course, where gunpowder may be safely used, as also candles, instead of Davy’s lamps, which give less light.

The quantity of air put down into the Wallsend colliery, at the time of the last dreadful accident, 18th June, 1835, was not less than 5000 cubic feet per minute, whence it has been justly inferred that the explosion was caused by the rashness of a wasteman carrying a light through a door into a foul drift.

Till the cutting out of the pillars commences (see the right end of the diagram), the ventilation of the several passages, boards, &c., may be kept perfect, supposing the working extended no further than _a_, or _b_; because, as long as there are pillars standing, every passage may be converted into an air-conduit, for leading a current of air in any direction, either to C, the burning, or D, the dumb furnace. But the first pillar that is removed deranges the ventilation at that spot, and takes away the means of carrying the air into the further recess towards _c_. In taking out the pillars, the miners always work to windward, that is to say, against the stream of air; so that, whatever gas may be evolved, shall be immediately carried off from the people at work. When a range of pillars has been removed, as at _d_, _e_, _f_, no power remains of dislodging the gas from the section of the mine beyond _a_, _b_; and as the pillars are successively cut away to the left hand of the line _a_, _b_, the size of the _goaf_, or void, is increased. This vacuity is a true gas-holder, or reservoir, continually discharging itself at the points _g_, _h_, _i_, into the circulating current, to be carried off by the gas-pipe drift at the dumb furnace, but not to be suffered ever to come in contact with flame of any description. The next range of working, is the line of pillars to the left of _a_, _b_; the coal having been entirely cleared out of the space to the right, where the place of the pillars is marked by dotted lines. The roof in the waste soon falls down, and gets fractured up to the next seam of coal, called the yard-coal seam, which, abounding in gas, sends it down in large quantities, and keeps the immense gasometer, or goaf below, continually replenished. See STOVE.

VERATRINE, is a vegetable alkali, of a poisonous nature, extracted from the seeds of the _Veratrum sabadilla_, the roots of the _Veratrum album_, or white hellebore, and of _Colchicum autumnale_, or meadow saffron, in which plants it exists combined chiefly with gallic acid. It is obtained in the form of a white powder. It has an acrid, burning taste, but without any bitterness; it has no smell; but when snuffed into the nostrils, it excites violent and dangerous sneezing. It melts at a heat of 122° F., and concretes, on cooling, into a transparent yellowish mass. It restores the blue colour of reddened litmus paper. It is hardly soluble in water or ether, but abundantly in alcohol. It consists of--carbon 66·75, hydrogen 8·54, nitrogen 5·04, and oxygen 19·60. Its saline compounds have an acrid and burning taste. Veratrine resembles strychnine and brucine, in its effects upon living bodies, producing tetanus and death in a moderate dose; notwithstanding which, it has been prescribed by some of our poison doctors, especially mixed with hog’s lard, in the form of frictions on the forehead, for nervous maladies; but seldom, I believe, with any good effects.

VERDIGRIS. (_Vert-de-gris_, Fr.; _Grünspan_, Germ.) The copper used in this manufacture, is formed into round sheets, from 20 to 25 inches diameter, by one twenty-fourth of an inch in thickness. Each sheet is then divided into oblong squares, from 4 to 6 inches in length, by 3 broad; and weighing about 4 ounces. They are separately beaten upon an anvil, to smooth their surfaces, to consolidate the metal, and to free it from scales. The refuse of the grapes, after the extraction of their juice, formerly thrown on to the dunghill, is now preserved for the purpose of making verdigris. It is put loosely into earthen vessels, which are usually 16 inches high, 14 in diameter at the widest part, and about 12 at the mouth. The vessels are then covered with lids, which are surrounded by straw mats. In this situation the materials soon become heated, and exhale an acid odour; the fermentation beginning at the bottom of the cask, and gradually rising till it actuate the whole mass. At the end of two or three days, the manufacturer removes the fermenting materials into other vessels, in order to check the process, lest putrefaction should ensue. The copper plates, if new, are now prepared, by rubbing them over with a linen cloth dipt in a solution of verdigris; and they are laid up alongside of one another to dry. If the plates are not subjected to this kind of preparation, they will become black, instead of green, by the first operation. When the plates are ready, and the materials in a fermenting state, one of them is put into the earthern vessel for 24 hours, in order to ascertain whether it be a proper period to proceed to the remaining part of the process. If, at the end of this period, the plate be covered with an uniform green layer, concealing the whole copper, every thing is right; but if, on the contrary, liquid drops hang on the surface of the metal, the workmen say the plates are _sweating_, and conclude that the heat of the fermented mass has been inadequate; on which account another day is allowed to pass before making a similar trial. When the materials are finally found to be ready, the strata are formed in the following manner. The plates are laid on a horizontal wooden grating, fixed in the middle of a vat, on whose bottom a pan full of burning charcoal is placed, which heats them to such a degree, that the women who manage this work are obliged to lay hold of them frequently with a cloth when they lift them out. They are in this state put into earthern vessels, in alternate strata with the fermented materials, the uppermost and undermost layers being composed of the expressed grapes. The vessels are covered with their straw mats, and left at rest. From 30 to 40 pounds of copper are put into one vessel.

At the end of 10, 12, 15, or 20 days the vessels are opened, to ascertain, by the materials having become white, if the operation be completed.

Detached glossy crystals will be perceived on the surface of the plates; in which case the grapes are thrown away, and the plates are placed upright in a corner of the verdigris cellar, one against the other, upon pieces of wood laid on the ground. At the end of two or three days they are moistened by dipping in a vessel of water, after which they are replaced in their former situation, where they remain seven or eight days, and are then subjected to momentary immersion, as before. This alternate moistening and exposure to air is performed six or eight times, at regular intervals of about a week. As these plates are sometimes dipped into damaged wine, the workmen term these immersions, _one wine_, _two wines_, &c.

By this treatment, the plates swell, become green, and covered with a stratum of verdigris, which is readily scraped off with a knife. At each operation every vessel yields from five to six pounds of verdigris, in a _fresh_ or _humid_ state; which is sold to wholesale dealers, who dry it for exportation. For this purpose, they knead the paste in wooden troughs, and then transfer it to leathern bags, a foot and a half long, and ten inches in diameter. These bags are exposed to the sun and air till the verdigris has attained a sufficient degree of hardness. It loses about half its weight in this operation; and it is said to be knife-proof, when this instrument, plunged through the leathern bag, cannot penetrate the loaf of verdigris.

The manufacture of verdigris at Montpellier is altogether domestic. In most wine farm-houses there is a verdigris cellar; and its principal operations are conducted by the females of the family. They consider the forming the strata, and scraping off the verdigris, the most troublesome part. Chaptal says that this mode of making verdigris would admit of some improvements: for example, the acetification requires a warmer temperature than what usually arises in the earthen vessels; and the plates, when set aside to generate the coat of verdigris, require a different degree of heat and moisture from that requisite for the other operations.

Verdigris is a mixture of the crystallized acetate of copper and the sub-acetate, in varying proportions. According to Vauquelin’s researches, there are three compounds of oxide of copper and acetic acid; 1. a subacetate, insoluble in water, but decomposing in that fluid, at common temperatures changing into peroxide and acetate; 2. a neutral acetate, the solution of which is not altered at common temperatures, but is decomposed by ebullition, becoming peroxide and superacetate; and, 3. superacetate, which in solution is not decomposed, either at common temperatures or at the boiling point; and which cannot be obtained in crystals, except by slow spontaneous evaporation, in air or _in vacuo_. The first salt, in the dry state, contains 66·51 of oxide; the second, 44·44; and the third, 33·34.

Mr. Phillips has given the following analyses of French and English verdigris; _Annals of Philosophy_, No. 21.--

French English Verdigris. Verdigris. Acetic acid 29·3 29·62 Peroxide of copper 43·5 44·25 Water 25·2 25·51 Impurity 2·0 0·62 ----- ------ 100·0 100·00

_Distilled verdigris_, as it was long erroneously called, is merely a _binacetate_ or superacetate of copper, made by dissolving, in a copper kettle, one part of verdigris in two of distilled vinegar; aiding the mutual action by slight heat and agitation with a wooden spatula. When the liquor has taken its utmost depth of colour, it is allowed to settle, and the clear portion is decanted off into well glazed earthen vessels. Fresh vinegar is poured on the residuum, and if its colour does not become deep enough, more verdigris is added. The clear and saturated solution is then slowly evaporated, in a vessel kept uniformly filled, till it acquires the consistence of syrup, and shows a pellicle on its surface; when it is transferred into glazed earthen pans, called _oulas_ in the country. In each of these dishes, two or three sticks are placed, about a foot long, cleft till within two inches of their upper end, and having the base of the cleft kept asunder by a bit of wood. This kind of pyramid is suspended by its summit in the liquid. All these vessels are transported into crystallizing rooms, moderately heated with a stove, and left in the same state for 15 days, taking care to maintain an uniform temperature. Thus are obtained very fine groups of crystals of acetate of copper, clustered round the wooden rods; on which they are dried, taken off, and sent into the market. They are distinctly rhomboidal in form, and of a lively deep blue colour. Each cluster of crystals weighs from five to six pounds; and, in general, their total weight is equal to about one-third of the verdigris employed.

The crystallized binacetate of commerce consists, by my analysis, of--acetic acid, 52; oxide of copper, 39·6; water, 8·4, in 100. I have prepared crystals which contain no water. There is a triple acetate of copper and lime, which resembles distilled verdigris in colour. It was manufactured pretty extensively in Scotland some years ago, and fetched a high price, till I published an analysis of it in the Edinburgh Philosophical Journal. It is much inferior, for all uses in the arts, to the proper binacetate.

VERDITER, or BLUE VERDITER. This is a precipitate of oxide of copper with lime, made by adding that earth, in its purest state, to the solution of nitrate of copper, obtained in quantities by the refiners, in parting gold and silver from copper by nitric acid. The cupreous precipitate must be triturated with lime, after it is nearly dry, to bring out the fine velvety blue colour. The process is delicate, and readily misgives in unskilful hands.

The _cendres bleues en pâte_ of the French, though analogous, are in some respects a different preparation. To make it, dissolve sulphate of copper in hot water, in such proportions that the liquid may have a density of 1·3. Take 240 pound measures of this solution, and divide it equally into 4 open-headed casks; add to each of these 45 pound measures of a boiling-hot solution of muriate of lime, of specific gravity 1·317, whereby a double decomposition will ensue; with the formation of muriate of copper and sulphate of lime, which precipitates. It is of consequence to work the materials well together at the moment of mixture, to prevent the precipitate agglomerating in unequal masses. After leaving it to settle for 12 hours, a small quantity of the clear liquor may be examined, to see whether the just proportions of the two salts have been employed, which is done by adding either sulphate of copper or muriate of lime. Should either cause much precipitation, some of the other must be poured in till the equivalent decomposition be accomplished; though less harm results from an excess of sulphate of copper than of muriate of lime.

The muriate of copper is to be decanted from the subsided gypsum, which must be drained and washed in a filter; and these blue liquors are to be added to the stronger; and the whole distributed, as before, into 4 casks; composing in all 670 pound measures of a green liquor, of 1·151 specific gravity.

Meanwhile, a magma of lime is to be prepared as follows:--100 pounds of quicklime are to be mixed up with 300 pounds of water, and the mixture is to be passed through a wire-gauze sieve, to separate the stony and sandy particles, and then to be ground in a proper mill to an impalpable paste. About 70 or 80 pounds of this mixture (the beauty of the colour is inversely as the quantity of lime) are to be distributed in equal portions between the four casks, strongly stirring all the time with a wooden spatula. It is then left to settle, and the limpid liquor is tested by ammonia, which ought to occasion only a faint blue tinge; but if the colour be deep blue, more of the lime paste must be added. The precipitate is now to be washed by decantation, employing for this purpose the weak washings of a former operation; and it is lastly to be drained and washed on a cloth filter. The proportions of material prescribed above, furnish from 500 to 540 pounds of green paste.

Before making further use of this paste, the quantity of water present in it must be determined by drying 100 or 200 grains. If it contain 27 per cent. of dry matter, 12 pounds of it may be put into a wooden bucket (and more or less in the ratio of 12 to to 27 per cent.) capable of containing 17-1/2 pints; a pound (measure) of the lime paste is then to be rapidly mixed into it; immediately afterwards, a pint and a quarter of a watery solution of the pearlash of commerce, of spec. grav. 1·114, previously prepared; and the whole mixture is to be well stirred, and immediately transferred to a colour-mill. The quicker this is done, the more beautiful is the shade.

On the other hand, two solutions must have been previously made ready, one of sal-ammoniac (4 oz. troy dissolved in 3-1/2 pints of water), and another of sulphate of copper (8 oz. troy dissolved in 3-1/2 pints of water).

When the paste has come entirely through the mill, it is to be quickly put into a jar, and the two preceding solutions are to be simultaneously poured into it; when a cork is to be inserted, and the jar is to be powerfully agitated. The cork must now be secured with a fat lute. At the end of four days this jar and three of its fellows are to be emptied into a large hogshead nearly full of clear water, and stirred well with a paddle. After repose, the supernatant liquid is run off; when it is filled up again with water, and elutriated several times in succession, till the liquid no longer tinges turmeric paper brown. The deposit may be then drained on a cloth filter. The pigment is sold in the state of a paste; and is used for painting, or printing paper-hangings for the walls of apartments.

The above prescribed proportions furnish the superfine blue paste: for the second quality, one-half more quicklime paste is used; and for the third, double of the lime and sal ammoniac; but the mode of preparation is in every case the same.

This paste may be dried into a blue powder, or into crayons for painters, by exposing it on white deals to a very gentle heat in a shady place. This is called _cendres bleues en pierre_.

VERDITER, or BREMEN GREEN. This pigment is a light powder, like magnesia, having a blue or bluish green colour. The first is most esteemed. When worked up with oil or glue, it resists the air very well; but when touched with lime, it is easily affected, provided it has not been long and carefully dried. A strong heat deprives it of its lustre, and gives it a brown or blackish-green tint.

The following is, according to M. J. G. Gentele, the process of fabrication in Bremen, Cassel, Eisenach, Minden, &c.:--

_a._ 225 lbs. of sea salt, and 222 lbs. of blue vitriol, both free from iron, are mixed in the dry state, then reduced between mill-stones with water to a thick homogeneous paste.

_b._ 225 lbs. of plates of old copper are cut by scissors into bits of an inch square, then thrown and agitated in a wooden tub containing two lbs. of sulphuric acid, diluted with a sufficient quantity of water, for the purpose of separating the impurities; they are afterwards washed with pure water in casks made to revolve upon their axes.

_c._ The bits of copper being placed in oxidation-chests, along with the magma of common salt and blue vitriol previously prepared in strata of half an inch thick, they are left for some time to their mutual reaction. The above chests are made of oaken planks joined without iron nails, and set aside in a cellar, or other place of moderate temperature.

The saline mixture, which is partially converted into sulphate of soda and chloride of copper, absorbs oxygen from the air, whereby the metallic copper passes into a hydrated oxide, with a rapidity proportioned to the extent of the surfaces exposed to the atmosphere. In order to increase this exposure, during the three months that the process requires, the whole mass must be turned over once every week, with a copper shovel, transferring it into an empty chest alongside, and then back into the former one.

At the end of three months, the corroded copper scales must be picked out, and the saline particles separated from the slimy oxide with the help of as little water as possible.

_d._ This oxidized _schlam_, or mud, is filtered, then thrown, by means of a bucket containing 30 pounds, into a tub, where it is carefully divided or comminuted.

_e._ For every six pailfuls of _schlam_ thus thrown into the large tub, 12 pounds of muriatic acid, at 15° Baumé, are to be added; the mixture is to be stirred, and then left at rest for 24 or 36 hours.

_f._ Into another tub, called the blue back, there is to be introduced, in like manner, for every six pailfuls of the acidified _schlam_, 15 similar pailfuls of a solution of colourless clear caustic alkali, at 19° Baumé.

_g._ When the back (_e_) has remained long enough at rest, there is to be poured into it a pail of pure water for every pail of _schlam_.

_h._ When all is thus prepared, the set of workmen who are to empty the back (_e_), and those who are to stir (_f_), must be placed alongside of each. The first set transfer the _schlam_ rapidly into the latter back; where the second set mix and agitate it all the time requisite to convert the mass into a consistent state, and then leave it at rest from 36 to 48 hours.

The whole mass is to be now washed; with which view it is to be stirred about with the affusion of water, allowed to settle, and the supernatant liquor is drawn off. This process is to be repeated till no more traces of potash remain among the blue. The deposit must be then thrown upon a filter, where it is to be kept moist, and exposed freely to the air. The pigment is now squeezed in the filter-bags, cut into bits, and dried in the atmosphere, or at a temperature not exceeding 78° Fahr. It is only after the most complete desiccation that the colour acquires its greatest lustre.

VERMICELLI, is a paste of wheat flour, drawn out and dried in slender cylinders, more or less tortuous, like worms, whence the Italian name. The _gruau_ of the French is wheat coarsely ground, so as to free it from the husk; the hardest and whitest part, being separated by sifting, is preferred for making the finest bread. When this _gruau_ is a little more ground, and the dust separated from it by the boulting-machine, the granular substance called _semoule_ is obtained, which is the basic of the best pastes. The softest and purest water is said to be necessary for making the most plastic vermicelli dough; 12 pounds of it being usually added to 50 pounds of _semoule_. It is better to add more _semoule_ to the water, than water to the _semoule_, in the act of kneading. The water should be hot, and the dough briskly worked while still warm. The Italians pile one piece of this dough upon another, and then tread it well with their feet for two or three minutes. They afterwards work it for two hours with a powerful rolling-pin, a bar of wood from 10 to 12 feet long, larger at the one end than the other, having a sharp cutting edge at the extremity, attached to the large kneading-trough.

When the dough is properly prepared, it is reduced to thin ribands, cylinders, or tubes, to form vermicelli and macaroni of different kinds. This operation is performed by means of a powerful press. This is vertical, and the iron plate or follower carried by the end of the screw fits exactly into a cast-iron cylinder, called the _bell_, like a sausage-machine, of which the bottom is perforated with small holes, of the shape and size intended for the vermicelli. The _bell_ being filled, and warmed with a charcoal fire to thin the dough into a paste, this is forced slowly through the holes, and is immediately cooled and dried by a fanner as it protrudes. When the threads or fillets have acquired the length of a foot, they are grasped by the hand, broken off, and twisted, while still flexible, into any desired shape upon a piece of paper.

The macaroni requires to be made of a less compact dough than the vermicelli. The former is forced through the perforated bottom, usually in fillets, which are afterwards formed into tubes by joining their edges together before they have had time to become dry. The _lazagnes_ are macaroni left in the fillet or riband shape.

VERMILLION, or _Cinnabar_, is a compound of mercury and sulphur in the proportion of 100 parts of the former to 16 of the latter, which occurs in nature as a common ore of quicksilver, and is prepared by the chemist as a pigment, under the name of Vermillion. It is, properly speaking, a bisulphuret of mercury. This artificial compound being extensively employed, on account of the beauty of its colour, in painting, for making red sealing-wax, and other purposes, is the object of an important manufacture. When vermillion is prepared by means of sublimation, it concretes in masses of considerable thickness, concave on one side, convex on the other, of a needle-form texture; brownish-red in the lump, but when reduced to powder of a lively red colour. On exposure to a moderate heat, it evaporates without leaving a residuum, if it be not contaminated with red lead; and at a higher heat, it takes fire, and burns entirely away, with a blue flame.

Holland long kept a monopoly of the manufacture of vermillion, from being alone in possession of the art of giving it a fine flame colour. Meanwhile the French chemists examined this product with great care, under an idea that the failure of other nations to rival the Dutch, arose from ignorance of its true composition; some, with Berthollet, imagined that it contained a little hydrogen; and others, with Fourcroy, believed that the mercury contained in it was oxidized; but, eventually, Seguin proved that both of these opinions were erroneous; having ascertained, on the one hand, that no hydrogenous matter was given out in the decomposition of cinnabar, and on the other that sulphur and mercury, by combining, were transformed into the red sulphuret in close vessels, without the access of any oxygen whatever. It was likewise supposed that the solution of the problem might be found in the difference of composition between the red and black sulphurets of mercury; and many conjectures were made with this view, the whole of which were refuted by Seguin. He demonstrated, in fact, that a mere change of temperature was sufficient to convert the one sulphuret into the other, without occasioning any variation in the proportion of the two elements. Cinnabar, moderately heated in a glass tube, is convertible into ethiops, which in its turn is changed into cinnabar by exposing the tube to a higher temperature; and thence he was led to conclude that the difference between these two sulphurets was owing principally to the state of the combination of the constituents. It would seem to result, from all these researches, that cinnabar is only an intimate compound of pure sulphur and mercury, in the proportions pointed out by analysis; and it is therefore reasonable to conclude, that in order to make fine vermillion, it should be sufficient to effect the union of its elements at a high enough temperature, and to exclude the influence of all foreign matters; but, notwithstanding these discoveries, the art of making good vermillion is nearly as much a mystery as ever. M. Seguin, indeed, announced in his Memoirs, that he had succeeded in obtaining, in his laboratory, as good a cinnabar as that of Holland, and at a remunerative price; but whatever truth may be in this assertion, or however much the author may have been excited by the love of honour and profit, no manufacture on the great scale sprung up under his auspices. France is still as tributary as ever to foreign nations for this chemical product. At an exposition some years ago, indeed, a sample of good French vermillion was brought forward to prove that the problem was nearly solved; but that it is not so completely, may be inferred from the silence on this subject in M. Dupin’s report of the last exposition, in 1834, where we see so many chemical trifles honoured with eulogiums and medals by the judges of the show. The English vermillion is now most highly prized by the French manufacturers of sealing-wax.

M. Tuckert, apothecary of the Dutch court, published, long ago, in the _Annales de Chimie_, vol. iv., the best account we yet have of the manufacture of vermillion in Holland; one which has been since verified by M. Payssé, who saw the process practised on the great scale with success.

“The establishment in which I saw, several times, the fabrication of sublimed sulphuret of mercury,” says M. Tuckert, “was that of Mr. Brand, at Amsterdam, beyond the gate of Utrecht; it is one of the most considerable in Holland, producing annually, from three furnaces, by means of four workmen, 48,000 pounds of cinnabar, besides other mercurial preparations. The following process is pursued here:--

“The ethiops is first prepared by mixing together 150 pounds of sulphur, with 1080 pounds of pure mercury, and exposing this mixture to a moderate heat in a flat polished iron pot, one foot deep, and two feet and a half in diameter. It never takes fire, provided the workman understands his business. The black sulphuret, thus prepared, is ground, to facilitate the filling with it of small earthen bottles capable of holding about 24 ounces of water; from 30 to 40 of which bottles are filled beforehand, to be ready when wanted.

“Three great subliming pots or vessels, made of very pure clay and sand, have been previously coated over with a proper lute, and allowed to dry slowly. These pots are set upon three furnaces bound with iron hoops, and they are covered with a kind of iron dome. The furnaces are constructed so that the flame may freely circulate and play upon the pots, over two-thirds of their height.

“The subliming vessels having been set in their places, a moderate fire is kindled in the evening, which is gradually augmented till the pots become red. A bottle of the black sulphuret is then poured into the first in the series, next into the second and third, in succession; but eventually, two, three, or even more, bottles may be emptied in at once; this circumstance depends on the stronger or weaker combustion of the sulphuret of mercury thus projected. After its introduction, the flame rises 4 and sometimes 6 feet high; when it has diminished a little, the vessels are covered with a plate of iron, a foot square, and an inch and a half thick, made to fit perfectly close. In this manner, the whole materials which have been prepared are introduced, in the course of 34 hours, into the three pots; being for each pot, 360 pounds of mercury, and 50 of sulphur; in all, 410 pounds.”

The degree of firing is judged of, from time to time, by lifting off the cover; for if the flame rise several feet above the mouth of the pot, the heat is too great; if it be hardly visible, the heat is too low. The proper criterion being a vigorous flame playing a few inches above the vessel. In the last of the 36 hours’ process, the mass should be dexterously stirred up every 15 or 20 minutes, to quicken the sublimation. The subliming pots are then allowed to cool, and broken to pieces in order to collect all the vermillion encrusted within them; and which usually amounts to 400 lbs., being a loss of only 60 on each vessel. The lumps are to be ground along with water between horizontal stones, elutriated, passed through sieves, and dried. It is said that the rich tone of the Chinese vermillion may be imitated by adding to the materials for subliming one per cent. of sulphuret of antimony, and by digesting the ground article first in a solution of sulphuret of potassa, and, finally, in diluted muriatic acid.

The humid process of Kirchoff has of late years been so much improved, as to furnish a vermillion quite equal in brilliancy to the Chinese. The following process has been recommended. Mercury is triturated for several hours with sulphur, in the cold, till a perfect ethiops is formed; potash lye is then added, and the trituration is continued for some time. The mixture is now heated in iron vessels, with constant stirring at first, but afterwards only from time to time. The temperature must be kept up as steadily as possible at 130° Fahr., adding fresh supplies of water as it evaporates. When the mixture which was black, becomes, at the end of some hours, brown-red, the greatest caution is requisite, to prevent the temperature from being raised above 114°, and to preserve the mixture quite liquid, while the compound of sulphur and mercury should always be pulverulent. The colour becomes red, and brightens in its hue, often with surprising rapidity. When the tint is nearly fine, the process should be continued at a gentler heat, during some hours. Finally, the vermillion is to be elutriated, in order to separate any particles of running mercury. The three ingredients should be very pure. The proportion of product varies with that of the constituents, as we see from the following results of experiments, in which 300 parts of mercury were always employed, and from 400 to 450 of water:--

Sulphur. Potash. Vermillion obtained. 114 75 330 115 75 331 120 120 321 150 152 382 120 180 245 100 180 244 60 180 142

The first proportions are therefore the most advantageous; the last, which are those of M. Kirchoff himself, are not so good.

Brunner found that 300 parts of quicksilver, 114 of sulphur, 75 of caustic potassa, and from 400 to 450 of water, form very suitable proportions for the moist process; that the best temperature was 113° F.; and that 122° was the highest limit of heat compatible with the production of a fine colour.

The theory of this process is by no means clear. We may suppose that a sulphuret of potassium and mercury is first formed, which is eventually destroyed, in proportion as the oxygen of the air acts upon the sulphuret of potassium itself. There may also be produced some hyposulphite of mercury, which, under the same influence, would be transformed into sulphuret of mercury and sulphate of potash.

Sulphuret of potassium and mercury furnish also vermillion, but it is not beautiful. Red oxide of mercury, calomel, turbith mineral, and the soluble mercury of Hahnemann, treated with the sulphuret of potassium, or the hydrosulphuret of ammonia, are all capable of giving birth to vermillion by the humid way.

The vermillion of commerce is often adulterated with red lead, brickdust, dragon’s blood, and realgar. The first two, not being volatile, remain when the vermillion is heated to its subliming point; the third gives a red tincture to alcohol; the fourth exhales its peculiar garlic smell with heat; and when calcined in a crucible with carbonate of soda, and nitre in excess, affords arsenic acid, which may be detected by the usual chemical tests.

VINEGAR MANUFACTORY, BY MALT. Annual produce, 100,000 gallons.

_Expenses for One Month._ _£ s. d._ Cost of material and fuel for 8,333 gallons, at 8-3/4_d._ 303 16 2 Wages to 8 workmen, at 25_s._ per week 40 0 0 Salaries to clerks, manager, and traveller 83 6 8 Travelling expensesat 30 0 0 Three horses’ keep 7 10 0 Rent and taxes 25 0 0 ----------- _£_489 12 10 -----------

Expenses for 5 months, at 489_l._ 12_s._ 10_d._ 2448 4 2 Duty on 41,665 gallons, at 2_d._ 347 4 2 Stock of utensils 1500 0 0 ------------ _£_4295 8 4 ------------

Produce of 100,000 gallons, at 1_s._ 8_d._ _£_8333 6 8 Expenses for 12 months, at 489_l._ 12_s._ 10_d._ _£_5875 18 0 Duty on 100,000 gallons, at 2_d._ 833 6 8 Interest on capital, 4295_l._ 8_s._ 4_d._ 214 4 5 --------- 6923 9 1 ------------ Net profit _£_1409 17 7 ------------

See ACETIC ACID.

VIOLET DYE, is produced by a mixture of red and blue colouring-matters, which are applied in succession. Silk is dyed a fugitive violet with either archil or brazil wood; but a fine fast violet, first by a crimson with cochineal, without tartar or tin mordant, and after washing, it is dipped in the indigo vat. A finish is sometimes given with archil. A violet is also given to silk, by passing it through a solution of verdigris, then through a bath of logwood, and, lastly, through alum water. A more beautiful violet may be communicated by passing the alumed silk through a bath of brazil wood, and after washing it in the river, through a bath of archil.

To produce violets on printed calicoes, a dilute acetate of iron is the mordant, and the dye is madder. The mordanted goods should be well dunged.

A good process for dyeing cottons violet, is--first, to gall, with 18 or 20 pounds of nut-galls for every 100 pounds of cotton; second, to pass the stuff; still hot, through a mordant composed of--alum, 10 pounds; iron-liquor, at 1-1/2° B., and sulphate of copper, each 5 or 6 pounds; water, from 24 to 28 gallons; working it well, with alternate steeping, squeezing, airing, dipping, squeezing, and washing; third, to madder, with its own weight of the root; and fourth, to brighten with soap. If soda be used at the end, instead of soap, the colour called _prune de monsieur_ will be produced; and by varying the doses of the ingredients, a variety of violet tints may be given.

The best violets are produced by dyeing yarn or cloth which has been prepared with oil as for the Turkey-red process. See MADDER.

For the violet _pruneau_, a little nitrate of iron is mixed with the alum mordant, which makes a black; but this is changed into _violet pruneau_, by a madder bath, followed by a brightening with soap.

VITRIFIABLE COLOURS; see ENAMELS, PASTES, POTTERY, and STAINED GLASS.

VITRIOL, from _vitrum_, glass, is the old chemical, and still the vulgar appellation of sulphuric acid, and of many of its compounds, which in certain states have a glassy appearance: thus--

Vitriolic acid, or oil of vitriol, is sulphuric acid; blue vitriol, is sulphate of copper; green vitriol, is green sulphate of iron; vitriol of Mars, is red sulphate of iron; and white vitriol, is sulphate of zinc.

W.

WACKE, is a massive mineral, intermediate between claystone and basalt. It is of a greenish-gray colour; vesicular in structure; dull, opaque; streak shining; soft, easily frangible; spec. grav. 2·55 to 2·9; it fuses like basalt.

WADD, is the provincial name of plumbago in Cumberland; and also of an ore of manganese in Derbyshire, which consists of the peroxide of that metal, associated with nearly its own weight of oxide of iron.

WADDING (_Ouate_, Fr.; _Watte_, Germ.); is the spongy web which serves to line ladies’ pelisses, &c. _Ouate_, or _Wat_, was the name originally given to the glossy downy tufts found in the pods of the plant commonly called _Apocyn_, and by botanists _Asclepias syriaca_, which was imported from Egypt and Asia Minor for the purpose of stuffing cushions, &c. Wadding is now made with a lap or fleece of cotton prepared by the carding-engine (see _Carding_, COTTON MANUFACTURE), which is applied to tissue paper by a coat of size, made by boiling the cuttings of hare-skins, and adding a little alum to the gelatinous solution. When two laps are glued with their faces together, they form the most downy kind of wadding.

WAFERS. There are two manners of manufacturing wafers: 1, with wheat flour and water, for the ordinary kind; and 2, with gelatine. 1. A certain quantity of fine flour is to be diffused through pure water, and so mixed as to leave no clotty particles. This thin pap is then coloured with one or other of the matters to be particularly described under the second head; and which are, vermillion, sulphate of indigo, and gamboge. The pap is not allowed to ferment, but must be employed immediately after it is mixed. For this purpose a tool is employed, consisting of two plates of iron, which come together like pincers or a pair of tongs, leaving a certain small definite space betwixt them. These plates are first slightly heated, greased with butter, filled with the pap, closed, and then exposed for a short time to the heat of a charcoal fire. The iron plates being allowed to cool, on opening them, the thin cake appears dry, solid, brittle, and about as thick as a playing-card. By means of annular punches of different sizes, with sharp edges, the cake is cut into wafers. 2. The transparent wafers are made as follows:--

Dissolve fine glue, or isinglass, in such a quantity of water, that the solution, when cold, may be consistent. Let it be poured hot upon a plate of mirror glass, (previously warmed with steam, and slightly greased,) which is fitted in a metallic frame, with edges just as high as the wafers should be thick. A second plate of glass, heated and greased, is laid on the surface, so as to touch every point of the gelatine, resting on the edges of the frame. By this pressure, the thin cake of gelatine is made perfectly uniform. When the two plates of glass get cold, the gelatine becomes solid, and may easily be removed. It is then cut with proper punches into discs of different sizes.

The colouring-matters ought not to be of an insalubrious kind.

For red wafers, carmine is well adapted, when they are not to be transparent; but this colour is dear, and can be used only for the finer kinds. Instead of it, a decoction of brazil wood, brightened with a little alum, may be employed.

For yellow, an infusion of saffron or turmeric has been prescribed; but a decoction of weld, fustic, or Persian berries, might be used.

Sulphate of indigo, partially saturated with potash, is used for the blue wafers; and this mixed with yellow, for the greens. Some recommend the sulphate to be nearly neutralized with chalk, and to treat the liquor with alcohol, in order to obtain the best blue dye for wafers.

Common wafers are, however, coloured with the substances mentioned at the beginning of the article; and for the cheaper kinds, red lead is used instead of vermillion, and turmeric instead of gamboge.

WALNUT HUSKS, or PEELS (_Brout des noix_, Fr.); are much employed by the French dyers for rooting or giving dun colours.

WARP (_Chaine_, Fr.; _Kette_, _Auschweif_, _Zettel_, Germ.); is the name of the longitudinal threads or yarns, whether of cotton, linen, silk, or wool, which being decussated at right angles by the woof or weft threads, form a piece of cloth. The warp yarns are parallel, and continuous from end to end of the web. See WEAVING, for a description of the _warping-mill_.

WASH, is the fermented wort of the distiller.

WASHING. See BLEACHING, and SCOURING.

WATERING OF STUFFS (_Moirage_, Fr.); is a process to which silk and other textile fabrics are subjected, for causing them to exhibit a variety of undulated reflections, and plays of light. It is produced by sprinkling water upon the goods, and then passing them through a calender, either with cold or hot rollers, plain or variously indented.

WATER-PROOF CLOTH. See CAOUTCHOUC, and GELATINE.

A patent was obtained, in August, 1830, by Mr. Thomas Hancock, for rendering textile fabrics impervious to water and air, by spreading the liquid juice of the caoutchouc tree upon the surfaces of the goods, and then exposing them to the air to dry. It does not appear that this project has been realized in our manufactures.

Mr. William Simpson Potter proposes, in his patent, of April, 1835, to render fabrics water-proof by imbuing them with a solution of isinglass, alum, and soap, by means of a brush applied to the wrong side of the cloth, distended upon a table. After it is dry, it must be brushed on the wrong side, against the grain. Then the brush is to be dipped in clean water, and passed lightly over the cloth. The gloss caused by the above application can be taken off by brushing the goods when they are dry. Cloth so prepared is said to be impervious to water, but not to air.

I have examined woollen cloth now on sale in a shop in the Strand, which may be breathed through with the greatest facility, but which retains water upon its surface, as is evinced by a body of water standing upon a concave piece of it tied over a show-glass in the window.

Mr. Sievier’s plan of rendering cloth water-proof, for which he obtained a patent in December, 1835, consists in spreading over it, with a brush, a solution of India rubber in spirits of turpentine, at one or more applications, and then applying a similar solution mixed with acetate of lead, litharge, sulphate of zinc, gum mastic, or other drying material. He next takes wool, or other textile material, cut into proper lengths, and spreads it upon the surface of the fabric varnished in this manner, for the purpose of forming the nap or pile. He then presses the cloth by means of rollers, or brushes, so as to fix the nap firmly to its surface.

WATERS, MINERAL--TABLE I. ANALYSES of the principal MINERAL WATERS of Germany.

+------------------------+-----------+----------+--------+-------+-------+ |Grains of Anhydrous | Carlsbad. | ms. |Schlesi-|Marien-|Auscho-| |Ingredients in One | | | scher. | bad. |witz. | |Pound Troy. | | | Ober- |Kreutz-|Ferdi- | | | | | salz- | br. |nands- | | | | |brunnen.| |brun- | | | | | | |nen. | +------------------------+-----------+----------+--------+-------+-------+ |Carbonate of Soda | 7·2712 | 8·0625 | 6·1133 | 5·3499| 4·5976| |Ditto of Lithia | 0·0150 | 0·0405 | 0·0127 | 0·0858| 0·0507| |Ditto of Baryta | -- | 0·0022 | -- | -- | -- | |Ditto of Strontia | 0·0055 | 0·0080 | 0·0165 | 0·0028| 0·0040| |Ditto of Lime | 1·7775 | 0·8555 | 1·7497 | 2·9509| 3·0085| |Ditto of Magnesia | 1·0275 | 0·5915 | 1·4107 | 2·0390| 2·2867| |Do. (Proto) of Manganese| 0·0048 | 0·0028 | -- | 0·0288| 0·0692| |Ditto (Proto) of Iron | 0·0208 | 0·0120 | 0·0480 | 0·1319| 0·2995| |Sub-Phos. of Lime | 0·0012 | -- | -- | -- | -- | |Ditto of Alumina | 0·0019 | 0·0014 | 0·0045 | -- | 0·0040| |Sulphate of Potassa | -- | 0·4050 | 0·2220 | -- | -- | |Ditto of Soda | 14·9019 | -- | 2·2095 |28·5868|16·9022| |Ditto of Lithia | -- | -- | -- | -- | -- | |Ditto of Lime | -- | -- | -- | -- | -- | |Ditto of Strontia | -- | -- | -- | -- | -- | |Ditto of Magnesia | -- | -- | -- | -- | -- | |Nitr. of Magnesia | -- | -- | -- | -- | -- | |Chlor. of Potassium | - - | 0·0338 | -- | -- | -- | |Ditto of Sodium | 5·9820 | 5·7255 | 0·8752 |10·1727| 6·7472| |Ditto of Magnesium | - - | -- | -- | -- | -- | |Fluoride of Calcium | 0·0184 | 0·0014 | -- | -- | -- | |Alumina | - - | -- | -- | 0·0023| -- | |Silica | 0·4329 | 0·3104 | 0·2531 | 0·2908| 0·5023| | +-----------+----------+--------+-------+-------+ |Total | 31·4606 | 16·0525 |12·9152 |49·6417|34·4719| | +-----------+----------+--------+-------+-------+ |Carbonic Acid Gas in 100| | | | | | |cubic inches | 58 | 51 | 98 | 105 | 146 | |Temperature (F.) |Sprud. 165°| | | | | | |Neub. 138°|Kess. 117°| 58° | 53° | 46° | | |Mühl. 128°|Krän. 84°| | | | | |Ther. 122°| | | | | |Analyzed by |Berzelius. |Struve. |Struve. |Berze- |Stein- | | | | | |lius. |mann. | +------------------------+-----------+----------+--------+-------+-------+

+------------------------+------+-------+------+-------+------+-------+ |Grains of Anhydrous |Eger. | Pyr- | Spa. | Fach- |Geil- | Selt- | |Ingredients in One |Fran- | mont. | Pou- |ingen. | nau. | zer. | |Pound Troy. |zens- | | hon. | | | | | |brun- | | | | | | | |nen. | | | | | | | | | | | | | | +------------------------+------+-------+------+-------+------+-------+ |Carbonate of Soda |3·8914| -- |0·5531|12·3328|4·9658| 4·6162| |Ditto of Lithia |0·0282| | | | | | |Ditto of Baryta | -- | -- | -- | -- | -- | 0·0014| |Ditto of Strontia |0·0023| -- | -- | -- | -- | 0·0144| |Ditto of Lime |1·3501| 4·7781|0·7387| 1·8667|2·2279| 1·4004| |Ditto of Magnesia |0·5040| -- |0·8425| 1·2983|1·6282| 1·5000| |Do. (Proto) of Manganese|0·0322| 0·0364|0·0389| -- | -- | -- | |Ditto (Proto) of Iron |0·1762| 0·3213|0·2813| -- | -- | -- | |Sub-Phos. of Lime |0·0172| -- |0·0102| 0·0061| -- | 0·0007| |Ditto of Alumina |0·0092| 0·0110|0·0064| -- | -- | 0·0020| |Sulphate of Potassa | -- | 0·0314|0·0598| -- |0·2154| 0·2978| |Ditto of Soda |8·3785| 1·6092|0·0289| 0·1267|0·0315| -- | |Ditto of Lithia | -- | 0·0067| -- | -- | -- | -- | |Ditto of Lime | -- | 5·0265| -- | -- | -- | -- | |Ditto of Strontia | -- | 0·0154| -- | -- | -- | -- | |Ditto of Magnesia | -- | 2·3684| -- | -- | -- | -- | |Nitr. of Magnesia | -- | -- | -- | -- | -- | -- | |Chlor. of Potassium | -- | -- | -- | -- | -- | 0·2685| |Ditto of Sodium |6·9229| -- |0·3371| 3·2337|0·4072|12·9690| |Ditto of Magnesium | -- | 0·8450| -- | -- | -- | -- | |Fluoride of Calcium | -- | -- | -- | -- | -- | 0·0013| |Alumina | -- | -- | -- | -- |0·0185| | |Silica |0·3548| 0·3727|0·3739| 0·0657|0·2021| 0·2265| | +------+-------+------+-------+------+-------+ |Total |1·6670|15·4221|3·2691|18·9300|9·6966|21·2982| | +------+-------+------+-------+------+-------+ |Carbonic Acid Gas in 100| | | | | | | |cubic inches | 154 | 160 | 136 | 135 | 163 | 126 | |Temperature (F.) | | | | | | | | | 53° | 56° | 50° | 50° | 51° | 58° | | | | | | | | | | | | | | | | | |Analyzed by |Berze-|Struve.|Stru- |Bi- |Stru- |Struve.| | |ius | |ve. |schoff.|ve. | | +------------------------+------+-------+------+-------+------+-------+

+------------------------+-------+-------+--------+ |Grains of Anhydrous | Selt- | Seid- |Püllna. | |Ingredients in One | zer. |schutz.| | |Pound Troy. | | | | | | | | | | | | | | | | | | | +------------------------+-------+-------+--------+ |Carbonate of Soda | 4·6162| | | |Ditto of Lithia | | | | |Ditto of Baryta | 0·0014| | | |Ditto of Strontia | 0·0144| | | |Ditto of Lime | 1·4004| 5·1045| 0·5775| |Ditto of Magnesia | 1·5000| 0·8235| 4·8045| |Do. (Proto) of Manganese| -- | 0·0032| | |Ditto (Proto) of Iron | -- | 0·0095| | |Sub-Phos. of Lime | 0·0007| 0·0117| 0·0026| |Ditto of Alumina | 0·0020| 0·0088| | |Sulphate of Potassa | 0·2978| 3·6705| 3·6000| |Ditto of Soda | -- |17·6220| 92·8500| |Ditto of Lithia | -- | | | |Ditto of Lime | -- | 1·1287| 1·9500| |Ditto of Strontia | -- | 0·0347| | |Ditto of Magnesia | -- |62·3535| 69·8145| |Nitr. of Magnesia | -- | 5·9302| | |Chlor. of Potassium | 0·2685| | | |Ditto of Sodium |12·9690| | | |Ditto of Magnesium | -- | 1·2225| 14·7495| |Fluoride of Calcium | 0·0013| | | |Alumina | | | | |Silica | 0·2265| 0·0900| 0·1320| | +-------+-------+--------+ |Total |21·2982|98·0133|188·4806| | +-------+-------+--------+ |Carbonic Acid Gas in 100| | | | |cubic inches | 126 | 20 | 7 | |Temperature (F.) | | | | | | 58° | 58° | 58° | | | | | | | | | | | |Analyzed by |Struve.|Struve.|Struve. | | | | | | +------------------------+-------+-------+--------+

TABLE II.--The COMPOSITION of other celebrated MINERAL WATERS.

+------------------------------+------+--------------------------+ |Names of the Springs. |Grains| Cubic Inches of Gases. | | | of +------+-----+------+------+ | |water.| Oxy- |Car- |Sulph.|Azote.| | | | gen. |bonic|hydro-| | | | | |acid.| gen. | | +------------------------------+------+------+-----+------+------+ | | | | | | | | Kilburn (1)--acidulous. |138240| -- | 84·0| 36·0 | -- | | | | | | | | |Sulphurous. | | | | | | | Harrowgate (2) |103643| -- | 8·0| 19·0 | 7·0 | | Moffat (2) |103643| -- | 1·0| 10·0 | 4·0 | | Aix-la-Chapelle (3) | 8940| -- | -- | 13·06| -- | | Enghein (4) | 92160| -- | 18·5| 7·0 | -- | | | | | | | | |Saline. | | | | | | | Seidlitz | 58309| -- | 8·0| -- | -- | | Cheltenham (5) |103643| -- | 30·3| 3·0 | 12·0 | | Plombieres (6) | 14600| -- | -- | -- | -- | | Dunblane (7) sp. gr. 1·00475| 7291| -- | -- | -- | -- | | Pitcaithley (7) | 7291| -- | 1·0| -- | -- | | | | | | | | |Chalybeate. | | | | | | | Tunbridge (3) |103643| 1·4 | 10·6| -- | 4·0 | | Brighton (8) | 58309| -- | 18·0| -- | -- | | Toplitz (9) | 22540| -- | -- | -- | -- | | | | | | | | |Calcareous, nearly pure. | | | | | | | Bath (10) | 15360| -- | 2·4| -- | -- | | Buxton (11) | 58309| -- | -- | -- | 2·0 | | Bristol (12) | 58309| -- | 30·3| -- | -- | | Matlock | 58309| -- | -- | -- | -- | | Malvern (13) | 58309| -- | -- | -- | -- | | | | | | | | | Dead Sea (14) sp. gr. 1·211 | 100| -- | -- | -- | -- | | Do. (15) sp. gr. 1·245 | | -- | -- | -- | -- | | Do. (16) sp. gr. 1·2283| | -- | -- | -- | -- | | Sea water, Forth (7) | 7291| -- | -- | -- | -- | +------------------------------+------+------+-----+------+------+

+------------------------------+--------------------------+ |Names of the Springs. | Carbonates of | | +-----+-----+-----+--------+ | |Soda.|Lime.|Mag- | Iron. | | | | |ne- | | | | | |sia. | | +------------------------------+-----+-----+-----+--------+ | | grs.|grs. |grs. | grs. | | Kilburn (1)--acidulous. | -- | 2·4 | 1·25| 0·3-1/4| | | | | | | |Sulphurous. | | | | | | Harrowgate (2) | -- |18·5 | 5·5 | -- | | Moffat (2) | -- | -- | -- | -- | | Aix-la-Chapelle (3) | -- |15·25| 5·89| -- | | Enghein (4) | -- |21·4 | 1·35| -- | | | | | | | |Saline. | | | | | | Seidlitz | -- | 6·7 |21·0 | -- | | Cheltenham (5) | -- | -- |12·5 | 5·0 | | Plombieres (6) | 36·0| 0·4 | -- | -- | | Dunblane (7) sp. gr. 1·00475| -- | 0·5 | -- | 0·17 | | Pitcaithley (7) | -- | 0·5 | -- | -- | | | | | | | |Chalybeate. | | | | | | Tunbridge (3) | -- | -- | -- | 1·0 | | Brighton (8) | -- | -- | -- | -- | | Toplitz (9) | 13·5|16·5 | -- | 32·5 | | | | | | | |Calcareous, nearly pure. | | | | | | Bath (10) | -- | 1·6 | -- | 0·004 | | Buxton (11) | -- |10·5 | -- | -- | | Bristol (12) | -- |13·5 | -- | -- | | Matlock | -- | -- | -- | -- | | Malvern (13) | 5·33| 1·6 | 0·92| 0·625 | | | | | | | | Dead Sea (14) sp. gr. 1·211 | -- | -- | -- | -- | | Do. (15) sp. gr. 1·245 | -- | -- | -- | -- | | Do. (16) sp. gr. 1·2283| -- | -- | -- | -- | | Sea water, Forth (7) | -- | -- | -- | -- | +------------------------------+-----+-----+-----+--------+

+------------------------------+--------------------------+ |Names of the Springs. | Sulphates of | | +------+------+------+-----+ | |Soda. |Lime. | Mag- |Iron.| | | | | ne- | | | | | | sia. | | +------------------------------+------+------+------+-----+ | | grs. | grs. | grs. | grs.| | Kilburn (1)--acidulous. |18·2 |13·0 |91·0 | -- | | | | | | | |Sulphurous. | | | | | | Harrowgate (2) | -- | -- | 0·5 | -- | | Moffat (2) | -- | -- | -- | -- | | Aix-la-Chapelle (3) | -- | -- | -- | -- | | Enghein (4) | -- |33·3 | 5·8 | -- | | | | | | | |Saline. | | | | | | Seidlitz | -- |41·1 |14·44 | -- | | Cheltenham (5) |48·0 |40·0 | -- | -- | | Plombieres (6) | 1·0 | -- | -- | -- | | Dunblane (7) sp. gr. 1·00475| 3·7 | -- | -- | -- | | Pitcaithley (7) | 0·9 | -- | -- | -- | | | | | | | |Chalybeate. | | | | | | Tunbridge (3) | -- | 1·25 | -- | -- | | Brighton (8) | -- |32·7 | -- |11·2 | | Toplitz (9) | -- | -- | -- | -- | | | | | | | |Calcareous, nearly pure. | | | | | | Bath (10) | 3·0 |18·0 | -- | -- | | Buxton (11) | -- | 2·5 | -- | -- | | Bristol (12) |11·2 |11·7 | -- | -- | | Matlock | -- |trace | -- | -- | | Malvern (13) | 2·896| -- | -- | -- | | | | | | | | Dead Sea (14) sp. gr. 1·211 | -- | ·054| -- | -- | | Do. (15) sp. gr. 1·245 | -- | -- | -- | -- | | Do. (16) sp. gr. 1·2283| -- | -- | -- | -- | | Sea water, Forth (7) |25·6 | -- | -- | -- | +------------------------------+------+------+------+-----+

+------------------------------+--------------------------+ |Names of the Springs. | Muriates of | | +-------+-----+------+-----+ | | Soda. |Lime.| Mag- |Pot- | | | | | ne- |ash. | | | | | sia. | | +------------------------------+-------+-----+------+-----+ | | grs. | grs.| grs.| grs.| | Kilburn (1)--acidulous. | 6·0 | 0·6 | 2·8 | -- | | | | | | | |Sulphurous. | | | | | | Harrowgate (2) |615·5 | 3·0 | 9·1 | -- | | Moffat (2) | 3·6 | -- | -- | -- | | Aix-la-Chapelle (3) | 6·21 | -- | -- | -- | | Enghein (4) | 2·4 | -- | 8·0 | -- | | | | | | | |Saline. | | | | | | Seidlitz | -- | -- | 36·5 | -- | | Cheltenham (5) | 5·0 | -- | 12·5 | -- | | Plombieres (6) | 2·0 | -- | -- | -- | | Dunblane (7) sp. gr. 1·00475| 21·0 |20·8 | -- | -- | | Pitcaithley (7) | 12·7 |20·2 | -- | -- | | | | | | | |Chalybeate. | | | | | | Tunbridge (3) | 0·5 | -- | 2·25| -- | | Brighton (8) | 12·2 | -- | 6·0 | -- | | Toplitz (9) | 61·3 |28·5 | -- | -- | | | | | | | |Calcareous, nearly pure. | | | | | | Bath (10) | 6·6 | -- | -- | -- | | Buxton (11) | 1·5 | -- | -- | -- | | Bristol (12) | 4·0 | -- | 7·25| -- | | Matlock | -- | -- | -- | -- | | Malvern (13) | 1·55 | -- | -- | -- | | | | | | | | Dead Sea (14) sp. gr. 1·211 | 10·676| 3·8 | 10·1 | | | Do. (15) sp. gr. 1·245 | 7·8 |10·6 | 24·2 | | | Do. (16) sp. gr. 1·2283| 6·95 | 4·0 | 15·31| | | Sea water, Forth (7) |159·3 | 5·7 | 35·5 |trace| | | | | |[70] | +------------------------------+-------+-----+------+-----+

+------------------------------+----+----+----+-----+ |Names of the Springs. |Sil-|Alu-|Res-|Tem- | | |ica.|mi- |ins.|pera-| | | |na. | |ture.| | | | | | | | | | | | | +------------------------------+----+----+----+-----+ | |grs.|grs.|grs.| | | Kilburn (1)--acidulous. | -- | -- | 6·0| cold| | | | | | | |Sulphurous. | | | | | | Harrowgate (2) | -- | -- | -- | cold| | Moffat (2) | -- | -- | -- | cold| | Aix-la-Chapelle (3) | -- | -- | -- | 143°| | Enghein (4) | -- | -- | -- | cold| | | | | | | |Saline. | | | | | | Seidlitz | -- | -- | -- | cold| | Cheltenham (5) | -- | -- | -- | cold| | Plombieres (6) | -- | -- | -- | cold| | Dunblane (7) sp. gr. 1·00475| -- | -- | -- | cold| | Pitcaithley (7) | -- | -- | -- | cold| | | | | | | |Chalybeate. | | | | | | Tunbridge (3) | -- | -- | -- | cold| | Brighton (8) |1·12| -- | -- | cold| | Toplitz (9) | -- |15·1| -- | cold| | | | | | | |Calcareous, nearly pure. | | | | | | Bath (10) | 0·4| -- | -- | 114°| | Buxton (11) | -- | -- | -- | 82°| | Bristol (12) | -- | -- | -- | 74°| | Matlock | -- | -- | -- | 66°| | Malvern (13) | -- | -- | -- | cold| | | | | | | | Dead Sea (14) sp. gr. 1·211 | | | | | | Do. (15) sp. gr. 1·245 | | | | | | Do. (16) sp. gr. 1·2283| | | | | | Sea water, Forth (7) | | | | | +------------------------------+----+----+----+-----+

(1) Schmesser. (2) Garnet. (3) Babington. (5) Fothergill. (6) Vauquelin. (7) Dr. Murray. (8) Marcet. (9) John. (10) Phillips. (11) Pearson. (12) Carrick. (13) Dr. Philip. (14) Dr. Marcet. (15) Klaproth. (16) M. Gay Lussac.

[70] Dr. Wollaston.

Mineral waters may, in most cases, be artificially prepared, by the skilful application of the knowledge derived from analysis, with such precision as to imitate very closely the native springs. When the various earthy or metallic constituents, are held in solution by carbonic acid, or sulphuretted, they should be placed along with their due proportions of water, in the receiver of the aerating machine (see SODA WATER), and then the proper quantity of gas should be injected into the water. Sufficient agitation will be given by the action of the forcing-pump to promote their solution.

WAX (_Cire_, Fr.; _Wachs_, Germ.); is the substance which forms the cells of bees. It was long supposed to be derived from the pollen of plants, swallowed by these insects, and merely voided under this new form; but it has been proved by the experiments, first of Mr. Hunter, and more especially of M. Huber, to be the peculiar secretion of a certain organ, which forms a part of the small sacs, situated on the sides of the median line of the abdomen of the bee. On raising the lower segments of the abdomen, these sacs may be observed, as also scales or spangles of wax, arranged in pairs upon each segment. There are none, however, under the rings of the males and the queen. Each individual has only eight wax sacs, or pouches; for the first and the last ring are not provided with them. M. Huber satisfied himself by precise experiments that bees, though fed with honey, or sugar alone, produced nevertheless a very considerable quantity of wax; thus proving that they were not mere collectors of this substance from the vegetable kingdom. The pollen of plants serves for the nourishment of the larvæ.

But wax exists also as a vegetable product, and may, in this point of view, be regarded as a concrete fixed oil. It forms a part of the green fecula of many plants, particularly of the cabbage; it may be extracted from the pollen of most flowers; as also from the skins of plums, and many stone fruits. It constitutes a varnish upon the upper surface of the leaves of many trees, and it has been observed in the juice of the _cow-tree_. The berries of the _Myrica angustifolia_, _latifolia_, as well as the _cerifera_, afford abundance of wax.

Bees’ wax, as obtained by washing and melting the comb, is yellow. It has a peculiar smell, resembling honey, and derived from it, for the cells in which no honey has been deposited, yield a scentless white wax. Wax is freed from its impurities, and bleached, by melting it with hot water or steam, in a tinned copper or wooden vessel, letting it settle, running off the clear supernatant oily-looking liquid into an oblong trough with a line of holes in its bottom, so as to distribute it upon horizontal wooden cylinders, made to revolve half immersed in cold water, and then exposing the thin ribbons or films thus obtained to the blanching action of air, light, and moisture. For this purpose, the ribbons are laid upon long webs of canvas stretched horizontally between standards, two feet above the surface of a sheltered field, having a free exposure to the sunbeams. Here they are frequently turned over, then covered by nets to prevent their being blown away by winds, and watered from time to time, like linen upon the grass field in the old method of bleaching. Whenever the colour of the wax seems stationary, it is collected, remelted, and thrown again into ribbons upon the wet cylinder, in order to expose new surfaces to the blanching operation. By several repetitions of these processes, if the weather proves favourable, the wax eventually loses its yellow tint entirely, and becomes fit for forming white candles. If it be finished under rain, it will become gray on keeping, and also lose in weight.

In France, where the purification of wax is a considerable object of manufacture, about four ounces of cream of tartar, or alum, are added to the water in the first melting-copper, and the solution is incorporated with the wax by diligent manipulation. The whole is left at rest for some time, and then the supernatant wax is run off into a settling cistern, whence it is discharged by a stopcock or tap, over the wooden cylinder revolving at the surface of a large water-cistern, kept cool by passing a stream continually through it.

The bleached wax is finally melted, strained through silk sieves, and then run into circular cavities in a moistened table, to be cast or moulded into thin disc pieces, weighing from two to three ounces each, and three or four inches in diameter.

Neither chlorine, nor even the chlorides of lime and alkalis, can be employed with any advantage to bleach wax, because they render it brittle, and impair its burning quality.

Wax purified, as above, is white and translucent in thin segments; it has neither taste nor smell; it has a specific gravity of from 0·960 to 0·966; it does not liquefy till it be heated to 154-1/2° F.; but it softens at 86°, becoming so plastic, that it may be moulded by the hand into any form. At 32° it is hard and brittle.

It is not a simple substance, but consists of two species of wax, which may be easily separated by boiling alcohol. The resulting solution deposits, on cooling, the waxy body called _cerine_. The undissolved wax, being once and again treated with boiling alcohol, finally affords from 70 to 90 per cent. of its weight of cerine. The insoluble residuum is the _myricine_ of Dr. John, so called because it exists in a much larger proportion in the wax of the _Myrica cerifera_. It is greatly denser than wax, being of the same specific gravity as water; and may be distilled without decomposition, which cerine undergoes. See these two articles.

Wax is adulterated sometimes with starch; a fraud easily detected by oil of turpentine, which dissolves the former, and leaves the latter substance; and more frequently with mutton suet. This fraud may be discovered by dry distillation; for wax does not thereby afford, like tallow, sebacic acid (benzoic), which is known by its occasioning a precipitate in a solution of acetate of lead. It is said that two per cent. of a tallow sophistication may be discovered in this way.

Bees’ wax imported for home consumption:--in 1835, unbleached, 4,449 cwts.; bleached, 243 cwts.;--in 1836, unbleached, 4,673 cwts.; bleached, 121 cwts. Duty, when from British possessions, 10_s._; from foreign, 30_s._

WAX, MINERAL, or _Ozocerite_, is a solid, of a brown colour, of various shades, translucent, and fusible like bees’ wax; slightly bituminous to the smell, of a foliated texture, a conchoidal fracture, but wanting tenacity, so that it can be pulverized in a mortar. Its specific gravity varies from 0·900 to 0·953. Candles have been made of it in Moldavia, which give a tolerable light. It occurs at the foot of the Carpathians near Slanik, beneath a bed of bituminous slate-clay, in masses of from 80 to 100 pounds weight. Layers of brown amber are found in the neighbourhood. It is associated with variegated sandstone, rock salt, and beds of coal (lignite?). It is analogous to _hatchetine_. Something similar has been discovered in a _trouble_ at Urpeth colliery, near Newcastle, 60 fathoms beneath the surface. _Ozocerite_ consists of different hydro-carburetted compounds associated together; the whole being composed, ultimately, of--hydrogen 14, carbon 86, very nearly.

WEAVING (_Tissage_, Fr.; _Weberei_, Germ.); is performed by the implement called _loom_ in English, _métier à tisser_ in French, and _weberstuhl_ in German. The process of warping must always precede weaving. Its object is to arrange all the longitudinal threads, which are to form the chain of the web, alongside of each other in one parallel plane. Such a number of bobbins, filled with yarn, must therefore be taken as will furnish the quantity required for the length of the intended piece of cloth. One-sixth of that number of bobbins is usually mounted at once in the warp mill, being set loosely in a horizontal direction upon wire skewers, or spindles, in a square frame, so that they may revolve, and give off the yarn freely. The warper sits at A, _fig._ 1159., and causes the reel B to revolve, by turning round with his hand the wheel C, with the endless rope or band D. The bobbins filled with yarn are placed in the frame E. There is a sliding piece at F, called the _heck_ box, which rises and falls by the coiling and uncoiling of the cord G, round the central shaft of the reef H. By this simple contrivance, the band of warp-yarns is wound spirally, from top to bottom, upon the reel. I, I, I, are wooden pins which separate the different bands. Most warping mills are of a prismatic form; having twelve, eighteen, or more sides. The reel is commonly about six feet in diameter, and seven feet in height, so as to serve for measuring exactly upon its periphery the total length of the warp. All the threads from the frame E, pass through the heck F, which consists of a series of finely-polished hard-tempered steel pins, with a small hole at the upper part of each, to receive and guide one thread. The heck is divided into two parts, either of which may be lifted by a small handle below, while their eyes are placed alternately. Hence, when one of them is raised a little, a vacuity is formed between the two bands of the warp; but when the other is raised, the vacuity is reversed. In this way, the lease is produced at each end of the warp, and it is preserved by appropriate wooden pegs. The lease being carefully tied up, affords a guide to the weaver for inserting his lease-rods. The warping mill is turned alternately from right to left, and from left to right, till a sufficient number of yarns are coiled round it to form the breadth that is wanted; the warper’s principal care being to tie immediately every thread as it breaks, otherwise deficiencies would be occasioned in the chain, injurious to the appearance of the web, or productive of much annoyance to the weaver.

The simplest and probably the most antient of looms, now to be seen in action, is that of the Hindu tanty, shown in _fig._ 1160. It consists of two bamboo rollers; one for the warp, and another for the woven cloth; with a pair of heddles, for parting the warp, to permit the weft to be drawn across between its upper and under threads. The shuttle is a slender rod, like a large netting needle, rather longer than the web is broad, and is made use of as a batten or lay, to strike home or condense each successive thread of weft, against the closed fabric. The Hindu carries this simple implement, with his water pitcher, rice pot, and hooka, to the foot of any tree which can afford him a comfortable shade; he there digs a large hole, to receive his legs, along with the treddles or lower part of the harness; he next extends his warp, by fastening his two bamboo rollers, at a proper distance from each other, with pins, into the sward; he attaches the heddles to a convenient branch of the tree overhead; inserts his great toes into two loops under the geer, to serve him for treddles; lastly, he sheds the warp, draws through the weft, and beats it close up to the web with his rod-shuttle or batten.

The European loom is represented in its plainest state, as it has existed for several centuries, in _fig._ 1161. A is the warp-beam, round which the chain, has been wound; B represents the flat rods, usually three in number, which pass across between its threads, to preserve the lease, or the plane of decussation for the weft; C shows the heddles or healds, consisting of twines looped in the middle, through which loops, the warp yarns are drawn, one half through the front heddle, and the other through the back one; by moving which, the decussation is readily effected. The yarns then pass through the dents of the REED under D, which is set in a movable swing-frame E, called the lathe, lay, and also batten, because it _beats_ home the weft to the web. The lay is freely suspended to a cross-bar F, attached by rulers, called the _swords_, to the top of the lateral standards of the loom, so as to oscillate upon it. The weaver, sitting on the bench G, presses down one of the treddles at H, with one of his feet, whereby he raises the corresponding heddle, but sinks the alternate one; thus sheds the warp, by lifting and depressing each alternate thread, through a little space, and opens a pathway or race-course for the shuttle to traverse the middle of the warp, upon its two friction rollers M, M. For this purpose, he lays hold of the picking-peg in his right hand, and, with a smart jerk of his wrist, drives the fly-shuttle swiftly from one side of the loom to the other, between the shed warp yarns. The shoot of weft being thereby left behind from the shuttle pirn or cop, the weaver brings home, by pulling, the lay with its reed towards him by his left hand, with such force as the closeness of the texture requires. The web, as thus woven, is wound up by turning round the cloth beam I, furnished with a ratchet-wheel, which takes into a holding tooth. The plan of throwing the shuttle by the picking-peg and cord, is a great improvement upon the old way of throwing it by hand. It was contrived exactly a century ago, by John Kay, of Bury in Lancashire, but then resident in Colchester, and was called the fly-shuttle, from its speed, as it enabled the weaver to make double the quantity of narrow cloth, and much more broad cloth, in the same time.

The cloth is kept distended, during the operation of weaving, by means of two pieces of hard wood, called a templet, furnished with sharp iron points in their ends, which take hold of the opposite selvages or lists of the web. The warp and web are kept longitudinally stretched by a weighted cord, which passes round the warp-beam, and which tends continually to draw back the cloth from its beam, where it is held fast by the ratchet tooth. See FUSTIAN, JACQUARD LOOM, REED, and TEXTILE FABRICS.

The greater part of plain weaving, and much even of the figured, is now performed by the power loom, called _métier mécanique à tisser_, in French. _Fig._ 1162. represents the cast-iron power loom of Sharp and Roberts. A, A´, are the two side uprights, or standards, on the front of the loom. D, is the great arch of cast iron, which binds the two sides together. E, is the front cross-beam, terminating in the forks _e_, _e_; whose ends are bolted to the opposite standards A, A´, so as to bind the framework most firmly together. G´, is the breast beam, of wood, nearly square; its upper surface is sloped a little towards the front, and its edge rounded off, for the web to slide smoothly over it, in its progress to the cloth beam. The beam is supported at its end upon brackets, and is secured by the bolts _g´_, _g´_. H, is the cloth beam, a wooden cylinder, mounted with iron gudgeons at its ends, that on the right hand being prolonged to carry the toothed winding wheel H´. _k´_ is a pinion in geer with H´. H´´, is a ratchet wheel, mounted upon the same shaft _h´´´_, as the pinion _h´_. _h´_, is the click of the ratchet wheel H´´. _k´´´_, is a long bolt fixed to the frame, serving as a shaft to the ratchet wheel H´´, and the pinion _h´_. I, is the front heddle-leaf, and I´, the back one. J, J, J´, J´, jacks or pulleys and straps, for raising and depressing the leaves of the heddles. J´´, is the iron shaft which carries the jacks or system of pulleys J, J, J´, J´. K, a strong wooden ruler, connecting the front heddle with its treddle. L, L´, the front and rear marches or treddle-pieces, for depressing the heddle leaves alternately, by the intervention of the rods _k_, (and _k´_, hid behind _k_). M, M, are the two swords (swing bars) of the lay or batten. N, is the upper cross-bar of the lay, made of wood, and supported upon the squares of the levers _n_, _n´_, to which it is firmly bolted. N´, is the lay-cap, which is placed higher or lower, according to the breadth of the reed; it is the part of the lay which the hand-loom weaver seizes with his hand, in order to swing it towards him. _n´_, is the reed contained between the bar N, and the lay-cap N´. O, O, are two rods of iron, perfectly round and straight, mounted near the ends of the batten-bar N, which serve as guides to the drivers or peckers _o_, _o_, which impel the shuttle. These are made of buffalo hide, and should slide freely on their guide-rods. O´, O´, are the fronts of the shuttle-boxes; they have a slight inclination backwards. P, is the back of them. See _figs._ 1163. and 1164. O´´, O´´ are iron plates, forming the bottoms of the shuttle-boxes. _p_, small pegs or pins, planted in the posterior faces P (_fig._ 1164.) of the boxes, round which the levers P´ turn. These levers are sunk in the substance of the faces P, turn round pegs _p_, being pressed from without inwards, by the springs _p´_. P´´, _fig._ 1162. (to the right of K,) is the whip or lever, (and Q´´, its centre of motion, corresponding to the right arm and elbow of the weaver,) which serves to throw the shuttle, by means of the pecking-cord _p´´_, attached at its other end to the drivers _o_, _o_.

On the axis of Q´´, a kind of eccentric or heart wheel is mounted, to whose concave part, the middle of the double band or strap _r_, being attached, receives impulsion; its two ends are attached to the heads of the bolts _r´_, which carry the stirrups _r´´_, that may be adjusted at any suitable height, by set screws.

S (see the left-hand side of _fig._ 1162.), is the moving shaft, of wrought iron, resting on the two ends of the frame, S´ (see the right-hand side), is a toothed wheel, mounted exteriorly to the frame, upon the end of the shaft S. S´´ (near S´), are two equal elbows, in the same direction, and in the same plane, as the shaft S, opposite to the swords M, M, of the lay.

Z, is the loose, and Z´, the fast pulley, or riggers, which receive motion from the steam-shaft of the factory, Z´´, a small fly-wheel, to regulate the movements of the main shaft of the loom.

T, is the shaft of the eccentric tappets, cams, or wipers, which press the treddle levers alternately up and down; on its right end is mounted T´, a toothed wheel in geer with the wheel S´, of one half its diameter. T´´, is a cleft clamping collar, which serves to support the shaft T.

U, is a lever, which turns round the bolt _u_, as well as the click _h´´_. U´, is the click of traction, for turning round the cloth beam, jointed to the upper extremity of the lever U; its tooth _u´_, catches in the teeth of the ratchet wheel H´´. _u´´_, is a long slender rod, fixed to one of the swords of the lay M, serving to push the lower end of the lever U, when the lay retires towards the heddle leaves.

X, is a wrought-iron shaft, extending from the one shuttle-box to the other, supported at its ends by the bearings _x_, _x_.

Y, is a bearing, affixed exteriorly to the frame, against which the spring bar Z, rests, near its top, but is fixed to the frame at its bottom. The spring falls into a notch in the bar Y, and is thereby held at a distance from the upright A, as long as the band is upon the loose pulley _z´_; but when the spring bar is disengaged, it falls towards A, and carries the band upon the fast pulley _z_, so as to put the loom in geer with the steam-shaft of the factory.

Weaving, by this powerful machine, consists of four operations: 1. to shed the warp by means of the heddle leaves, actuated by the tappet wheels upon the axis Q´, the rods _k_, _k´_, the cross-bar E, and the eyes of the heddle leaves I, I´; 2. to throw the shuttle (see _fig._ 1161.), by means of the whip lever P´´, the driver cord _p_, and the pecker _o_; 3. to drive home the weft by the batten N, N´; 4. to unwind the chain from the warp beam, and to draw it progressively forwards, and wind the finished web upon the cloth beam H, by the click and toothed wheel mechanism at the right-hand side of the frame. For more minute details, the reader may consult _The Cotton Manufacture of Great Britain_, vol. ii. p. 291.

WEFT (_Trame_, Fr.; _Eintrag_, Germ.); is the name of the yarns or threads which run from selvage to selvage in a web.

WELD (_Vouëde_, Fr.; _Wau_, _Gelbkraut_, Germ.); is an annual herbaceous plant, which grows all over Europe, called by botanists _Reseda luteola_. The stems and the leaves dye yellow; and among the dyes of organic nature, they rank next to the Persian berry for the beauty and fastness of colour. The whole plant is cropped when in seed, at which period its dyeing power is greatest; and after being simply dried, is brought into the market.

Chevreul has discovered a yellow colouring principle in weld, which he has called _luteoline_. It may be sublimed, and thus obtained in long needle-form, transparent yellow crystals. Luteoline is but sparingly soluble in water; but it nevertheless dyes alumed silk and wool of a fine jonquil colour. It is soluble in alcohol and ether; it combines with acids, and especially with bases.

When weld is to be employed in the dye-bath, it should be boiled for three quarters of an hour; after which the exhausted plant is taken out, because it occupies too much room. The decoction is rapidly decomposed in the air, and ought therefore to be made only when it is wanted. It produces with,

Solution of isinglass a slight turbidity. Litmus paper a faint reddening. Potash lye a golden yellow tint. Solution of alum a faint yellow. Protoxide salts of tin a rich yellow } Acetate of lead ditto } precipitation. Salts of copper a dirty yellow-brown } Sulphate of red oxide of iron a brown, passing into olive.

A lack is made from decoction of weld with alum, precipitated by carbonate of soda or potassa. See YELLOW DYE.

WELDING (_Souder_, Fr.; _Schweissen_, Germ.); is the property which pieces of wrought iron possess, when heated to whiteness, of uniting intimately and permanently under the hammer, into one body, without any appearance of junction. The welding temperature is usually estimated at from 60° to 90° of Wedgewood. When a skilful blacksmith is about to perform the welding operation, he watches minutely the effect of the heat in his forge-fire upon the two iron bars; and if he perceives them beginning to burn, he pulls them out, rolls them in sand, which forms a glassy silicate of iron upon the surface, so as to prevent further oxidizement; and then laying the one properly upon the other, he incorporates them by his right-hand hammer, being assisted by another workman, who strikes the metal at the same time with a heavy forge-hammer.

_Platinum_ is not susceptible of being welded, as many chemical authors have erroneously asserted.

Mr. T. H. Russell, of Handsworth, near Birmingham, obtained a patent, in May, 1836, for manufacturing welded iron tubes, by drawing or passing the skelp, or fillet of sheet iron, five feet long, between dies or holes, formed by a pair of grooved rollers, placed with their sides contiguous; for which process, he does not previously turn up the skelp from end to end, but he does this so as to bring the edges together at the time when the welding is performed. He draws the skelp through two or more pairs of the above pincers or dies, each of less dimension than the preceding. In making tubes of an inch of internal diameter, a skelp four inches and a half broad is employed. The twin rollers revolve on vertical axes, which may be made to approach each other to give pressure; and they are kept cool by a stream of water, while the skelp, ignited to the welding heat, is passed between them. They are affixed at about a foot in front of the mouth of the furnace, on a draw-bench; there being a suitable stop within a few inches of the rollers, against which the workman may place a pair of pincers, having a bell-mouthed hole or die, for welding and shaping the tube. In the first passage between the rollers, a circular revolving plate of iron is let down vertically between them, to prevent the edges of the skelp from overlapping, or even meeting. The welding is performed at the last passage.

WELLS, ARTESIAN. See also ARTESIAN WELLS. The following account of a successful operation of this kind, lately performed at Mortlake, in Surrey, deserves to be recorded. The spot at which this undertaking was begun, is within 100 feet of the Thames. In the first instance, an auger, seven inches in diameter, was used in penetrating 20 feet of superficial detritus, and 200 feet of London clay. An iron tube, 8 inches in diameter, was then driven into the opening, to dam out the land-springs and the percolation from the river. A 4-inch auger was next introduced through the iron tube, and the boring was continued until, the London clay having been perforated to the depth of 240 feet, the sands of the plastic clay were reached, and water of the softest and purest nature was obtained; but the supply was not sufficient, and it did not reach the surface. The work was proceeded with accordingly; and after 55 feet of alternating beds of sand and clay had been penetrated, the chalk was touched upon. A second tube, 4-1/2 inches in diameter, was then driven into the chalk, to stop out the water of the plastic sands; and through this tube an auger, 3-1/2 inches in diameter, was introduced, and worked down through 35 feet of hard chalk, abounding with flints. To this succeeded a bed of soft chalk, into which the instrument suddenly penetrated to the depth of 15 feet. On the auger being withdrawn, water gradually rose to the surface, and overflowed. The expense of the work did not exceed 300_l._ The general summary of the strata penetrated is as follows:--Gravel, 20 feet; London clay, 250; plastic sands and clays, 55; hard chalk with flints, 35; soft chalk, 15; = 375 feet.

WHALEBONE (_Baleine_, Fr.; _Fischbeine_, Germ.); is the name of the horny laminæ, consisting of fibres laid lengthwise, found in the mouth of the whale, which, by the fringes upon their edges, enable the animal to allow the water to flow out, as through rows of teeth (which it wants), from between its capacious jaws, but to catch and detain the minute creatures upon which it feeds. The fibres of whalebone have little lateral cohesion, as they are not transversely decussated, and may, therefore, be readily detached in the form of long filaments or bristles. The _blades_, or scythe-shaped plates, are externally compact, smooth, and susceptible of a good polish. They are connected, in a parallel series, by what is called the _gum_ of the animal, and are arranged along each side of its mouth, to the number of about 300. The length of the longest _blade_, which is usually found near the middle of the series, is the gauge adopted by the fishermen to designate the size of the fish. The greatest length hitherto known has been 15 feet, but it rarely exceeds 12 or 13. The breadth, at the root end, is from 10 to 12 inches; and the average thickness, from four to five tenths of an inch. The series, viewed altogether in the mouth of the whale, resemble, in general form, the roof of a house. They are cleansed and softened before cutting, by boiling for two hours in a long copper.

Whalebone, as brought from Greenland, is commonly divided into portable junks or pieces, comprising ten or twelve blades in each; but it is occasionally subdivided into separate blades, the gum and the hairy fringes having been removed by the sailors during the voyage. The price of whalebone fluctuates from 50_l._ to 150_l._ per ton. The blade is cut into parallel prismatic slips, as follows:--It is clamped horizontally, with its edge up and down, in the large wooden vice of a carpenter’s bench, and is then planed by the following tool: _fig._ 1165. A, B, are its two handles; C, D, is an iron plate, with a guide-notch E; F, is a semicircular knife, screwed firmly at each end to the ends of the iron plate C, D, having its cutting edge adjusted in a plane, so much lower than the bottom of the notch E, as the thickness of the whalebone slip is intended to be; for different thicknesses, the knife may be set by the screws at different levels, but always in a plane parallel to the lower guide surface of the plate C, D. The workman, taking hold of the handles A, B, applies the notch of the tool at the end of the whalebone blade furthest from him, and with his two hands pulls it steadily along, so as to shave off a slice in the direction of the fibres; being careful to cut none of them across. These prismatic slips are then dried, and planed level upon their other two surfaces. The fibrous matter detached in this operation, is used, instead of hair, for stuffing mattresses.

From its flexibility, strength, elasticity, and lightness, whalebone is employed for many purposes: for ribs to umbrellas or parasols; for stiffening stays; for the framework of hats, &c. When heated by steam, or a sand-bath, it softens, and may be bent or moulded, like horn, into various shapes, which it retains, if cooled under compression. In this way, snuff-boxes, and knobs of walking-sticks, may be made from the thicker parts of the blade. The surface is polished at first with ground pumice-stone, felt, and water; and finished with dry quicklime, spontaneously slaked, and sifted.

WHEAT. (_Triticum vulgare_, Linn.; _Froment_, Fr.; _Waizen_, Germ.) See BREAD, GLUTEN, and STARCH.

WHEEL CARRIAGES. Though this manufacture belongs most properly to a treatise upon mechanical engineering, I shall endeavour to describe the parts of a carriage, so as to enable gentlemen to judge of its make and relative merits. The external form may vary with every freak of fashion; but the general structure of a vehicle, as to lightness, elegance, and strength, may be judged of from the following figure and description.

_Fig._ 1166. shows the body of a chariot, hung upon an iron carriage, with iron wheels, axletrees, and boxes; the latter, by a simple contrivance, is close at the out-head, by which means the oil cannot escape; and the fastening of the wheel being at the in-head, as will be explained afterwards, gives great security, and prevents the possibility of the wheel being taken off by any other carriage running against it.

_Fig._ 1167. shows the arm of an axletree, turned perfectly true, with two collars in the solid, as seen at G and H. The parts from G to B are made cylindrical. At K is a screw nail, the purpose of which will be explained in _fig._ 1171.

_Fig._ 1168. is the longitudinal section of a metal nave, which also forms the bush, for the better fitting of which to the axletree, it is bored out of the solid, and made quite air-tight upon the pin; and for retaining the oil, it is left close at the out-head D.

_Fig._ 1169. represents a collet, made of metal, turned perfectly true, the least diameter of which is made the same with that part of the axletree M, _fig._ 1167., and its greatest diameter the same with that of the solid collar G, _fig._ 1167. This collet is made with a joint at S, and opens at _p_. Two grooves are represented at _qq_, _qq_, which are seen at the same letters in _fig._ 1170., as also the dovetail _r_, in both figures.

_Fig._ 1170. is an edge view of the collet, _fig._ 1169.

_Fig._ 1171. is a longitudinal section of an axletree arm, nave or bush, and fastening. A, B, is the arm of the axletree, bored up the centre from B to E. C, C, D, the nave, which answers also for the bush. P, S, the collet (see _figs._ 1169. and 1170.), put into its place. _q_, _q_, two steel pins, passing through the in-head of the bush, and filling up the grooves in the collet. W, W, a caped hoop, sufficiently broad to cover the ends of said pins, and made fast to the bush by screws. This hoop, when so fastened to the bush, prevents the possibility of the pins _q_, _q_, from getting out of their places. _u_, _u_, is a leather washer, interposed betwixt the in-head of the bush and the larger solid collar of the axletree, to prevent the escape of oil at the in-head. K, is a screw, the head of which is near the letter K, in _fig._ 1167. This screw being undone, and oil poured into the hole, it flows down the bore in the centre of the axletree arm, and fills the space B, left by the arm being about one inch shorter than the bore of the bush, and the screw, being afterwards replaced, keeps all tight. In putting on the wheel, a little oil ought to be put into the space betwixt the collet P, S, and the larger collar. The collar P, S, being movable round the axletree arm, and being made fast to the bush by means of the two pins _q_, _q_, revolves along with the bush, acting against the solid collar G, of the arm, and keeps the wheel fast to the axletree, until by removing the caped hoop W, W, and driving out the pins _q_, _q_, the collet becomes disengaged from the bush.

The dovetail, seen upon the collet at _r_, _fig._ 1170., has a corresponding groove cut in the bush, to receive it, in consequence of which the wheel must of necessity be put on so that the collet and pins fit exactly. These wheels very rarely require to be taken off, and they will run a thousand miles without requiring fresh oiling.

The spokes of the wheel, made of malleable iron, are screwed into the bush or nave at C, C, _figs._ 1168. 1171., all round. The felloes, composed merely of two bars of iron, bent into a circle edgeways, are put on, the one on the front, the other on the back, of the spokes, which have shoulders on both sides to support the felloes, and all three are attached together by rivets through them. The space between the two iron rings forming the felloes, should be filled up with light wood, the tire then put on, and fastened to the felloes by bolts and glands clasping both felloes.

This is a carriage without a mortise or tenon, or wooden joint of any kind. It is, at an average, one-seventh lighter than any of those built on the ordinary construction.

The design of Mr. W. Mason’s patent invention, of 1827, is to give any required pressure to the ends of what are called mail axletrees, in order to prevent their shaking in the boxes of the wheels. This object is effected by the introduction of leather collars in certain parts of the box, and by a contrivance, in which the outer cap is screwed up, so as to bear against the end of the axletree with any degree of tightness, and is held in that situation, without the possibility of turning round, or allowing the axletree to become loose.

_Fig._ 1172. shows the section of the box of a wheel, with the end of the axletree secured in it. The general form of the box, and of the axle, is the same as other mail axles, there being recesses in the box for the reception of oil. At the end of the axle, a cap _a_, is inserted, with a leather collar enclosed in it, bearing against the end of the axle; which cap, when screwed up sufficiently tight, is held in that situation by a pin or screw passed through the cap _a_, into the end of the iron box; a representation of this end of the iron box being shown at _fig._ 1173.

In the cap _a_, there is also a groove for conducting the oil to the interior of the box, with a screw at the opening, to prevent it running out as the wheel goes round.

The particular claims of improvement are, the leather collar against the end of the axle; the pin going through one of the holes in the end of the box, to fix it; and the channel for conducting the oil.

Mr. Mason’s patent, of August, 1830, applies also to the boxes and axles of that construction of carriage wheels which are fitted with the so called mail-boxes; but part of the invention applies to other axles.

_Fig._ 1174. represents the nave of a wheel, with the box for the axle within it, both shown in section longitudinally; _fig._ 1175. is a section of the axle, taken in the same direction; and _fig._ 1176. represents the screw cap and oil-box, which attaches to the outer extremity of the axle-box. Supposing the parts were put together, that is, the axle inserted into the box, then the intention of the different parts will be perceived.

The cylindrical recess _a_, in the box of the nave, is designed to fit the cylindrical part of the axle _b_; and the conical part _c_, of the axle, to shoulder up against a corresponding conical cavity in the box, with a washer of leather to prevent its shaking. A collar _d_, formed by a metallic ring, fits loosely upon a cylindrical part of the axle, and is kept there by a flange or rim, fixed behind the cone _c_. Several strong pins _f_, _f_, are cast into the back part of the box; which pins, when the wheel is attached, pass through corresponding holes in the collar _d_; and nuts being screwed on to the ends of the pins _f_, behind the collar, keep the wheel securely attached to the axle. The screw-cap _g_, is then inserted into the recess _h_, at the outer part of the box, its conical end and small tube _i_, passing into the recess _k_, in the end of the axle.

The parts being thus connected, the oil contained within the cap _g_, will flow through the small tube _i_, in its end, into the recess or cylindrical channel _l_, within the axle, and will thence pass through a small hole in the side of the axle, into the cylindrical recess _a_, of the box; and then lodging in the groove and other cavities within the box, will lubricate the axle as the wheel goes round. There is also a small groove cut on the outside of the axle, for conducting the oil, in order that it may be more equally distributed over the surface and the bearings. This construction of the box and axle, as far as the lubrication goes, may be applied to the axles of wheels in general; but that part of the invention which is designed to give greater security in the attachment of the wheel to the carriage, applies particularly to mail axles.

Mr. William Mason’s patent invention for wheel carriages, of August, 1831, will be understood by reference to the annexed figures. _Fig._ 1177. is a plan showing the fore-axletree bed _a_, _a_, of a four-wheeled carriage, to which the axletrees _b_, _b_, are jointed at each end; _fig._ 1178. is an enlarged plan; and _fig._ 1179. an elevation, or side view of one end of the said fore-axletree bed, having a Collinge’s axletree jointed to the axletree bed, by means of the cylindrical pin or bolt _c_, which passes through and turns in a cylindrical hole _d_, formed at the end of the axletree bed, shown also in the plan view, _fig._ 1180., and section, _fig._ 1181.

The axletree _b_, is firmly united with the upper end _e_, of the pin or bolt _c_; and to the lower end of it, which is squared, the guide piece _f_, is also fitted, and secured by the screw _g_, and cap or nut _h_, seen in _fig._ 1179., and in section in _fig._ 1182. There are leather washers _i_, _i_, let into recesses made to receive them in the parts _a_, _b_, and _f_, the intent of which is to prevent the oil from escaping that is introduced through the central perpendicular hole seen in _fig._ 1182., which hole is closed by means of a screw inserted into it. The oil is diffused, or spread over the surface of the cylinder _c_, by means of a side branch leading from the bottom of the hole into a groove formed around the cylinder, and also by means of two longitudinal gaps or cavities made within the hole, as shown in _figs._ 1180. and 1181. The guide piece _f_, is affixed at right angles with the axletree _b_, as shown in _fig._ 1178., and turns freely and steadily in the cylindrical hole _d_, made to receive one end of the iron fore-axletree bed _a_. In like manner, the opposite fore axletree _b_, _fig._ 1177., is jointed to the other end of the iron fore-axletree bed. The outer ends of the guide pieces _f_, _f_, are jointed to the splinter-bar _n_, _fig._ 1181, as follows:--_Fig._ 1183. is a plan, and _fig._ 1184. a section of the joint _o_, in _fig._ 1177., shown on an enlarged scale; a cylindrical pin or bolt _c_, is firmly secured in the splinter-bar, and round the lower part of the said pin or bolt the guide piece _f_, turns, and is made fast in its place by the screw _g_, and screwed nut _h_.

Oil is conveyed to the lower part of the cylindrical pin _c_, in a similar manner to that already described, and two leather washers are likewise furnished, to prevent its escape. The connecting joint at the opposite end of the splinter-bar _n_, is constructed in a similar manner. The futchel or socket _p_, _p_, for the pole of the carriage, must also be jointed to the middle of the fore-axletree bed and splinter-bar, in a similar manner. The swingletrees _q_, _q_, _fig._ 1177., are likewise jointed in the same way to the splinter-bar. _Fig._ 1185. is a side view of these parts. The fore wheels of the carriage, _fig._ 1177., are furnished with cast-iron boxes, as usual. The dotted lines show the action of the pole _p_, _p_, upon the splinter-bar _n_, and as communicated through the latter to the guide pieces _f_, _f_, connected with the axletrees _b_, _b_, so as to lock the wheels _r_, _r_, as shown in that figure.

The axletree may be incased in the woodwork of the fore-bed of the carriage, as usual, and as shown by dotted lines in the back end view thereof, _fig._ 1186.; and the framing _s_, _fig._ 1187., may be affixed firmly upon the said woodwork, in any fit and proper manner, as well as the fore-springs _t_, _t_, shown in _figs._ 1186. and 1187., and likewise in the side view, _fig._ 1188. In certain cases it may be desirable to fix the cylindrical pin or bolt _c_, firmly in the splinter-bar _n_, in the manner shown in _figs._ 1189. and 1190.; the swingletrees _q_, _q_, and guide pieces _f_, _f_, turning freely above and below upon the said pin or bolt, and secured in their places thereon by screws and screwed nuts, oil being also supplied through holes formed in both ends of the said pin or bolt, and leather washers provided, as in the above-described instances.

Mr. Gibbs, engineer, and Mr. Chaplin, coach-maker, obtained a patent, in 1832, for the construction of a four-wheeled carriage which shall be enabled to turn within a small compass, by throwing the axles of all the four wheels simultaneously into different positions. They effect this object by mounting each wheel upon a separate jointed axle, and by connecting the free ends of the four axles by jointed rods or chains, with the pole and splinter-bar in front of the carriage.

To fix the ends of the spokes of wheels to the felloe or rim, with greater security than had been effected by previous methods, is the object of a contrivance for which William Howard obtained a patent, in February, 1830. _Fig._ 1191. shows a portion of a wheel constructed on this new method; _a_, is the nave, of wood; _b_, _b_, _b_, wooden spokes, inserted into the nave in the usual way; _c_, _c_, is the rim or felloe, intended to be formed by one entire circle of wrought iron; _d_, and _e_, _e_, are the shoes or blocks, of cast iron, for receiving the ends of the spokes, which are secured by bolts to the rim on the inner circumference. The cap of the block _d_, is removed, for the purpose of showing the internal form of the block; _e_, _e_, have their caps fixed on, as they would appear when the spokes are fitted in. One of the caps or shoes is shown detached, upon a larger scale, at _fig._ 1192., by which it will be perceived that the end of the spoke is introduced into the shoe on the side. It is proposed that the end of the spoke shall not reach quite to the end of the recess formed in the block, and that it shall be made tight by a wedge driven in. The wedge piece is to be of wood, as _fig._ 1193., with a small slip of iron within it; and a hole is perforated in the back of the block or shoe, for the wedge to be driven through. When this is done, the ends of the spokes become confined and tight; and the projecting extremities of the wedges being cut off, the caps are then attached on the face of the block, as at _e_, _e_, by pins riveted at their ends, which secures the spokes, and renders it impossible for them to be loosened by the vibrations as the wheel passes over the ground. One important use of the wedges, is to correct the eccentric figure of the wheel, which may be readily forced out in any part that may be out of the true form, by driving the wedge up further; and this, it is considered, will be a very important advantage, as the nearer a wheel can be brought to a true circle, the easier it will run upon the road. The periphery of the wheel is to be protected by a tire, which may be put on in pieces, and bolted through the felloe; or it may be made in one ring, and attached, while hot, in the usual way.

Mr. Reedhead’s patent improvements in the construction of carriages, are represented in the following figures. They were specified in July, 1833.

_Fig._ 1194. is a plan or horizontal view of the fore part of a carriage, intended to be drawn by horses, showing the fore wheels in their position when running in a straight course; _fig._ 1195. is a similar view, showing the wheels as locked, when in the act of turning; _fig._ 1196. is a front end elevation of the same; _fig._ 1197. is a section taken through the centre of the fore axletree; and _fig._ 1198. is a side elevation of the general appearance of a stage-coach, with the improvements appended: _a_, _a_, are two splinter-bars, with their roller-bolts, for connecting the traces of the harness; these splinter-bars are attached, by the bent irons _b_, _b_, to two short axletrees or axle-boxes _c_, _c_, which carry the axles of the fore wheels _d_, _d_, and turn upon vertical pins or bolts _e_, _e_, passed through the fore axletree _f_, the splinter-bars and axle-boxes being mounted so as to move parallel to each other, the latter partaking of any motion given to the splinter-bars by the horses in drawing the carriage forward, and thereby producing the locking of the wheels, as shown _fig._ 1195.; and in order that the two wheels, and their axles and axle-boxes, together with the splinter-bars _a_, _a_, may move simultaneously, the latter are connected by pivots to the end of the links or levers _g_, _g_, which are attached to the arms _i_, _i_, which receive the pole of the coach by a hinge-joint or pin _h_; the arms _i_, _i_, turning on a vertical fulcrum-pin _k_, passed through the main axletree, _f_, as the pole is moved from one side to the other.

The axles _o_, _o_, are firmly fixed into the naves of the wheels, as represented in the side view of a wheel detached, at _fig._ 1200., the axles being mounted so as to revolve within their boxes in the following manner:--The axle-boxes, which answer the purpose of short axletrees, are formed of iron, and consist of one main or bottom plate _l_, seen best in _figs._ 1200. and 1199.; upon this bottom plate is formed the chamber _m_, _m_, carrying the two anti-friction rollers _n_, _n_, which turn on short axles passed through the sides and partition at the upper part of the chambers. These anti-friction rollers bear upon the cylindrical parts of the axle _o_, of each wheel, and support the weight of the coach; _p_, is a bearing firmly secured in the axle-box to the plate _l_, for the end of the axle _o_, to run in, the axle being confined in its proper situation by a collar and screw-nut on its end; _e_, is the vertical pin or bolt before mentioned, upon which the axle-bar turns when the wheels are locking, which bolt is enlarged within the box, and has an eye for the axle to pass through, being firmly secured to the plate _l_, and also to the sides of the box. _Fig._ 1200. is a plan or horizontal view of an axle and its box, belonging to one of the fore wheels; a piece _q_, is fixed to the under side of the main axletree, which supports the ends of the plates _l_, and thereby relieves the pins _e_, _e_, of the strain they would otherwise have to withstand. The axles of the hind wheels are mounted upon similar plates _l_, _l_, with bearings and chambers with anti-friction rollers; but as these are not required to lock, the plates _l_, _l_, are fixed on to the under side of the hind axletree by screw-nuts; there are small openings or doors, which can be removed for the purpose of unscrewing the nuts and collars of the bearings _p_, when the wheel is required to be taken off the carriage, when the axle can be withdrawn from the boxes. If it should be thought necessary, other chambers with friction rollers, may be placed on the under side of the plate _l_, to bear up the end of the axles, and relieve the bearing _p_. In order to stop or impede the progress of a carriage in passing down hills, there is a grooved friction or brake wheel _t_, fixed, by clamps or otherwise, on to the spokes of one of the hind wheels; _u_, is a brake-band or spring, of metal, encircling the friction wheel, one end of which band is fixed into the standard _v_, upon the hind axletree, and the other end connected by a joint to the shorter end of the lever _w_, which has its fulcrum in the standard _v_; this lever extends up to the hind seat of the coach, as shown in _fig._ 1198., and is intended to be under the command of the guard or passengers of the coach, and when descending a hill, or on occasion of the horses running away, the longer end of the lever is to be depressed, which will raise the shorter end, and, consequently, bring the band or spring _u_, in contact with the surface of the friction wheel, and thereby retard its revolution, and prevent the coach travelling too fast; or, instead of attaching the friction brake to the hind wheel, as represented in _fig._ 1198., it may be adapted to the fore wheels, and the end of the lever brought up to the side of the foot-board, or under it, and within command of the coachman, the standard which carries the fulcrum being made to move upon a pivot, to accommodate the locking of the wheels. It will be observed, that by these improved constructions of the carriage, and mode of locking the patentee is enabled to use much larger fore wheels than in common, and that the splinter-bars will always be in the position of right angles with the track or way of the horses in drawing the carriage, by which they are much relieved, and always pull in a direct and equal manner.

A manifest defect in all four-wheeled carriages, involving vast superfluous friction, is the small size of the front wheels; a defect which has existed ever since Walter Rippon made “the first hollow _turning_ coach with pillars and arches for her majesty Queen Mary, being then her servant,” until the railroad era, when our engineers remedied the defect by equalizing the wheels, at the expense of another defect--sacrificing the power of turning, and thus producing great lateral friction; whence a train of evil consequences result:--necessarily increased strength, and consequently increased weight of the carriages; increased power and weight of the engine to draw them, and overcome the friction; and, of course, increased strength of rails, and greater solidity of railway.

These defects are at last remedied by an invention patented by Mr. William Adams, author of a work entitled “English Pleasure Carriages.” Instead of placing the perch-bolt, or turning centre, as is commonly done, over the front axle, he places it at a convenient distance _between_ the front and hind axles; so that when turning the carriage the front wheels, instead of turning _beneath_ the body, as is common, turn outside of it, and the driver’s seat turns with them; thus giving him a perfect command over his horses in all positions, instead of the usual dangerous plan, which renders a driver liable to be pulled off his box by a restive horse, when in the act of turning. A carriage constructed on Mr. Adams’ plan may also be driven round a corner at full speed, without any risk of overturning, as the weight is equally poised on the axles in all positions. It is well known that the oversetting of stage coaches usually takes place when turning a corner, the momentum urging the vehicle in a right line, while the horses are pulling at an angle. By the new arrangement the front wheels may be made equal to the hind ones, or of any desirable height, and at the same time the body may be kept as low as may be thought convenient, even almost close to the ground, if desired. Thus two important objects, hitherto deemed incompatible, are combined--high wheels and a low centre of gravity. These carriages are therefore essentially safety carriages, while the friction is reduced to a minimum. The principle, in its various modifications, is applicable to every variety of carriage, both those of the simply useful kind, and those where beauty of form and colour are prime requisites.

Another most important part of Mr. Adams’ invention, is his new mode of spring suspension; applying the principle of the bow and string, for the first time, to obviate the effects of concussion in wheel carriages. All the springs hitherto in use for wheel carriages, have been friction springs, composed of long sliding surfaces, uncertain in their action, and liable to quick destruction by rust. But Mr. Adams’ springs are essentially elastic, being formed of single plates abutting endways, so that all friction is removed, and they can be hermetically sealed within paint to prevent their corrosion. He has various modes of applying the bow, either single or double, above or below the axle; but one most important feature is, that the axle being attached to the flexible cords or braces, the concussion which affects the wheels, either laterally, vertically, or in the line of progress, is perfectly intercepted, without the unpleasant oscillation experienced in carriages where the same purpose is accomplished by the use of the curved or C spring. Mr. Adams’ brace being, at the same time, a non-conductor of sound, the rattling of the wheels does not annoy the rider as in ordinary carriages. His springs are equally applicable to vehicles with two and four wheels.

The advantages of these carriages may be thus summed up:--A great diminution of the total weight; a diminution of resistance in draught equal to about one third; increase of safety to the riders; increased durability of the vehicle; absence of noise and vibration; absence of oscillation.

To these qualities, so desirable to all, and especially those of delicate nervous temperament, may be added--greater economy, both in the first cost and maintenance.

The _whirling_ public so blindly follows fashionable caprice in the choice of a carriage, as to have hitherto paid too little attention to this fundamental improvement; but many intelligent individuals have fully verified its practical reality. Having inspected various forms of two-wheeled and four-wheeled carriages, in the patentee’s premises in Drury Lane, I feel justified in recommending them as being constructed on the soundest mechanical principles; and have no doubt, that if reason be allowed to decide upon their merits, they will ere long be universally preferred by all who seek for easy-moving, safe, and comfortable vehicles.

WHETSLATE, is a massive mineral of a greenish-gray colour; feebly glimmering; fracture, slaty or splintery; fragments tabular; translucent on the edges; feels rather greasy; and has a spec. grav. of 2·722. It occurs in beds, in primitive and transition slates. Very fine varieties of whetslate are brought from Turkey, called _honestones_, which are in much esteem for sharpening steel instruments.

WHEY (_Petit lait_, Fr.; _Molken_, Germ.); is the greenish-gray liquor which exudes from the curd of milk. Scheele states, that when a pound of milk is mixed with a spoonful of proof spirit, and allowed to become sour, the whey filtered off, at the end of a month or a little more, is a good vinegar, devoid of lactic acid.

WHISKEY; is dilute alcohol, distilled from the fermented worts of malt or grains.

WHITE LEAD, _Carbonate of lead, or Ceruse_. (_Blanc de plomb_, Fr.; _Bleiweiss_, Germ.) This preparation is the only one in general use for painting wood and the plaster walls of apartments white. It mixes well with oil, without having its bright colour impaired, spreads easily under the brush, and gives a uniform coat to wood, stone, metal, &c. It is employed either alone, or with other pigments, to serve as their basis, and to give them body. This article has been long manufactured with much success at Klagenfurth in Carinthia, and its mode of preparation has been lately described with precision by Marcel de Serres. The great white-lead establishments at Krems, whence, though incorrectly, the terms _white of Kremnitz_ became current on the continent, have been abandoned.

1. The lead comes from Bleyberg; it is very pure, and particularly free from contamination with iron, a point essential to the beauty of its factitious carbonate. It is melted in ordinary pots of cast iron, and cast into sheets of varying thickness, according to the pleasure of the manufacturer. These sheets are made by pouring the melted lead upon an iron plate placed over the boiler; and whenever the surface of the metal begins to consolidate, the plate is slightly sloped to one side, so as to run off the still liquid metal, and leave a lead sheet of the desired thinness. It is then lifted off like a sheet of paper; and as the iron plate is cooled in water, several hundred weight of lead can be readily cast in a day. In certain white-lead works these sheets are one twenty-fourth of an inch thick; in others, half that quantity; in some, one of these sheets takes up the whole width of the conversion-box; in others, four sheets are employed. It is of consequence not to smooth down the faces of the leaden sheets; because a rough surface presents more points of contact, and is more readily attacked by acid vapours, than a polished one.

2. These plates are now placed so as to expose an extensive surface to the acid fumes, by folding each other over a square slip of wood. Being suspended by their middle, like a sheet of paper, they are arranged in wooden boxes, from 4-1/2 to 5 feet long, 12 to 14 inches broad, and from 9 to 11 inches deep. The boxes are very substantially constructed; their joints being mortised; and whatever nails are used, being carefully covered. Their bottom is made tight with a coat of pitch about an inch thick. The mouths of the boxes are luted over with paper, in the works where fermenting horsedung is employed as the means of procuring heat, to prevent the sulphuretted and phosphuretted hydrogen from injuring the purity of the white lead. In Carinthia it was formerly the practice, as also in Holland, to form the lead sheets into spiral rolls, and to place them so coiled up in the chests; but this plan is not to be recommended, because these rolls present obviously less surface to the action of the vapours, are apt to fall down into the liquid at the bottom, and thus to impair the whiteness of the lead. The lower edges of the sheets are suspended about two inches and a half from the bottom of the box; and they must not touch either one another or its sides, for fear of obstructing the vapours in the first case, or of injuring the colour in the second. Before introducing the lead, a peculiar acid liquor is put into the box, which differs in different works. In some, the proportions are four quarts of vinegar, with four quarts of wine-lees; and in others, a mixture is made of 20 pounds of wine-lees, with 8-1/2 pounds of vinegar, and a pound of carbonate of potash. It is evident that in the manufactories where no carbonate of potash is employed in the mixture, and no dung for heating the boxes, it is not necessary to lute them.

3. The mixture being poured into the boxes, and the sheets of lead suspended within them, they are carried into a stove-room, to receive the requisite heat for raising round the lead the corrosive vapours, and thus converting it into carbonate. This apartment is heated generally by stoves, is about 9 feet high, 30 feet long, and 24 feet wide, or of such a size as to receive about 90 boxes. It has only one door.

The heat should never be raised above 86° Fahr.; and it is usually kept up for 15 days, in which time the operation is, for the most part, completed. If the heat be too high, and the vapours too copious, the carbonic acid escapes in a great measure, and the metallic lead, less acted upon, affords a much smaller product.

When the process is well managed, as much carbonate of lead is obtained, as there was employed of metal; or, for 300 pounds of lead, 300 of ceruse are procured, besides a certain quantity of metal after the crusts are removed, which is returned to the melting-pot. The mixture introduced into the boxes serves only once; and if carbonate of potash has been used, the residuary matter is sold to the hatters.

4. When the preceding operation is supposed to be complete, the sheets, being removed from the boxes, are found to have grown a quarter of an inch thick, though previously not above a twelfth of that thickness. A few pretty large crystals of acetate of lead are sometimes observed on their edges. The plates are now shaken smartly, to cause the crust of carbonate of lead formed on their surfaces to fall off. This carbonate is put into large cisterns, and washed very clean. The cistern is of wood, most commonly of a square shape, and divided into from seven to nine compartments. These are of equal capacity, but unequal height, so that the liquid may be made to overflow from one to the other. Thereby, if the first chest is too full, it decants its excess into the second, and so on in succession. See RINSING MACHINE.

The water poured into the first chest, passes successively into the others, a slight agitation being meanwhile kept up, and there deposits the white lead diffused in it proportionally, so that the deposit of the last compartment is the finest and lightest. After this washing, the white lead receives another, in large vats, where it is always kept under water. It is lastly lifted out in the state of a liquid paste, with wooden spoons, and laid on drying-tables to prepare it for the market.

The white lead of the last compartment is of the first quality, and is called on the continent silver white. It is employed in fine painting.

When white lead is mixed in equal quantities with ground sulphate of barytes, it is known in France and Germany by the name of Venice white. Another quality, adulterated with double its weight of sulphate of barytes, is styled Hamburgh white; and a fourth, having three parts of sulphate to one of white lead, gets the name of Dutch white. When the sulphate of barytes is very white, like that of the Tyrol, these mixtures are reckoned preferable for certain kinds of painting, as the barytes communicates opacity to the colour, and protects the lead from being speedily darkened by sulphureous smoke or vapours.

The high reputation of the white lead of Krems was by no means due to the barytes, for the first and whitest quality was mere carbonate of lead. The freedom from silver of the lead of Villach, a very rare circumstance, is one cause of the superiority of its carbonate; as well as the skilful and laborious manner in which it is washed, and separated from any adhering particle of metal or sulphuret.

In England, lead is converted into carbonate in the following way.--The metal is cast into the form of a network grating, in moulds about 15 inches long, and 4 or 5 broad. Several rows of these are placed over cylindrical glazed earthen pots, about 4 or 5 inches in diameter, containing some treacle-vinegar, which are then covered with straw; above these pots another range is piled, and so in succession, to a convenient height. The whole are imbedded in spent bark from the tan-pit, brought into a fermenting state by being mixed with some bark used in a previous process. The pots are left undisturbed under the influence of a fermenting temperature for eight or nine weeks. In the course of this time the lead gratings become, generally speaking, converted throughout into a solid carbonate, which when removed is levigated in a proper mill, and elutriated with abundance of pure water. The plan of inserting coils of sheet lead into earthenware pipkins containing vinegar, and imbedding the pile of pipkins in fermenting horsedung and litter, is now little used; because the coil is not uniformly acted on by the acid vapours, and the sulphuretted hydrogen evolved from the dung is apt to darken the white lead.

In the above processes, the conversion of lead into carbonate, seems to be effected by keeping the metal immersed in a warm, humid atmosphere, loaded with carbonic and acetic acids; and hence a pure vinegar does not answer well; but one which is susceptible, by its spontaneous decomposition in these circumstances, of yielding carbonic acid. Such are tartar, wine-lees, molasses, &c.

Another process has lately been practised to a considerable extent in France, though it does not afford a white lead equal in body and opacity to the products of the preceding operations. M. Thenard first established the principle, and MM. Brechoz and Leseur contrived the arrangements of this new method, which was subsequently executed on a great scale by MM. Roard and Brechoz.

A subacetate of lead is formed by digesting a cold solution of uncrystallized acetate, over litharge, with frequent agitation. It is said that 65 pounds of purified pyrolignous acid, of specific gravity 1·056, require, for making a neutral acetate, 58 pounds of litharge; and hence, to form the subacetate, three times that quantity of base, or 174 pounds, must be used. The compound is diluted with water, as soon as it is formed, and being decanted off quite limpid, is exposed to a current of carbonic acid gas, which, uniting with the two extra proportions of oxide of lead in the subacetate, precipitates them in the form of a white carbonate, while the liquid becomes a faintly acidulous acetate. The carbonic acid may be extricated from chalk, or other compounds, or generated by combustion of charcoal, as at Clichy; but in the latter case, it must be transmitted through a solution of acetate of lead before being admitted into the subacetate, to deprive it of any particles of sulphuretted hydrogen. When the precipitation of the carbonate of lead is completed, and well settled down, the supernatant acetate is decanted off, and made to act on another dose of litharge. The deposit being first rinsed with a little water, this washing is added to the acetate; after which the white lead is thoroughly elutriated. This repetition of the process may be indefinitely made; but there is always a small loss of acetate, which must be repaired, either directly or by adding some vinegar.

In order to obtain the finest white lead by the process with earthen pots containing vinegar buried in fermenting tan, and covered by a grating of lead, the metal should be so thin as to be entirely convertible into carbonate; for whenever any of it remains, it is apt to give a gray tint to the product: if the temperature of the fermenting mass is less than 90° Fahr., some particles of the metal will resist the action of the vinegar, and degrade the colour; and if it exceeds 122°, the white verges into yellow, in consequence of some carbonaceous compound being developed from the principles of the acetic acid. The dung and tan have been generally supposed to act in this process by supplying carbonic acid, the result of their fermentation; but it is now said that this explanation is inexact, because the best white lead can be obtained by the entire exclusion of air from the pots in which the carbonation of the metal is carried on. We are thence led to conclude that the lead is oxidized at the expense of the oxygen of the vinegar, and carbonated by the agency of its oxygen and carbon; the hydrogen of the acid being left to associate itself with the remaining oxygen and carbon, so as to constitute an ethereous compound: thus, supposing the three atoms of oxygen to form, with one of lead and one of carbon, an atom of carbonate, then the remaining three atoms of carbon and three of hydrogen would compose olefiant gas.

It is customary on the continent to mould the white lead into conical loaves, before sending them into the market. This is done by stuffing well-drained white lead into unglazed earthen pots, of the requisite size and shape, and drying it to a solid mass, by exposing these pots in stove-rooms. The moulds being now inverted on tables, discharge their contents, which then receive a final desiccation; and are afterwards put up in pale-blue paper, to set off the white colour by contrast. Nothing in all the white-lead process is so injurious as this pot operation; a useless step, fortunately unknown in Great Britain. Neither greasing the skin, nor wearing thick gloves, can protect the operators from the diseases induced by the poisonous action of the white lead; and hence they must be soon sent off to some other department of the work.

It has been supposed that the differences observed between the ceruse of Clichy and the common kinds, depend on the greater compactness of the particles of the latter, produced by their slower aggregation; as also, according to M. Robiquet, on the former containing considerably less carbonic acid. See _infrà_.

Mr. Ham proposed, in a patent dated June, 1826, to produce white lead with the aid of the following apparatus, _a_, _a_, (_fig._ 1201.) are the side-walls of a stove-room, constructed of bricks; _b_, is the floor of bricks laid in Roman cement; _c_, _c_, are the side-plates, between which and the walls, a quantity of refuse tanner’s bark, or other suitable vegetable matter, is to be introduced. The same material is to be put also into the lower part at _d_ (upon a false bottom of grating?) The tan should rise to a considerable height, and have a series of strips of sheet lead _e_, _e_, _e_, placed upon it, which are kept apart by blocks or some other convenient means, with a space open at one end of the plates, for the passage of the vapours; but above the upper plates, boards are placed, and covered with tan, to confine them there. In the lower part of the chamber, coils of steam-pipe _f_, _f_, are laid in different directions to distribute heat; _g_, is a funnel-pipe, to conduct vinegar into the lower part of the vessel; and _h_, is a cock to draw it off, when the operation is suspended. The acid vapours raised by the heat, pass up through the spent bark, and on coming into contact with the sheets of lead, corrode them. The quantity of acid liquor should not be in excess; a point to be ascertained by means of the small tube _i_, at top, which is intended for testing it by the tongue. _k_, is a tube for inserting a thermometer, to watch the temperature, which should not exceed 170° Fahr. I am not aware of what success has attended this patented arrangement. The heat prescribed is far too great.

A magnificent factory has been recently erected at West Bromwich, near Birmingham, to work a patent lately granted to Messrs. Gossage and Benson, for making white lead by mixing a small quantity of acetate of lead in solution with slightly damped litharge, contained in a long stone trough, and passing over the surface of the trough currents of hot carbonic acid, while its contents are powerfully stirred up by a travelling-wheel mechanism. The product is afterwards ground and elutriated, as usual. The carbonic acid gas is produced from the combustion of coke. I am told that 40 tons of excellent white lead are made weekly by these chemico-mechanical operations.

Messrs. Button and Dyer obtained a patent about a year and a half ago, for making white lead by transmitting a current of purified carbonic acid gas, from the combustion of coke, through a mixture of litharge and nitrate of lead, diffused and dissolved in water, which is kept in constant agitation and ebullition by steam introduced through a perforated coil of pipes at the bottom of the tub. The carbonate of lead is formed here upon the principle of Thenard’s old process with the subacetate; for the nitrate of lead forms with the litharge a subnitrate, which is forthwith transformed into carbonate and neutral nitrate, by the agency of the carbonic acid gas. I have discovered that all sorts of white lead produced by precipitation from a liquid, are in a semi-crystalline condition; appear, therefore, semi-transparent, when viewed in the microscope; and do not cover so well as white lead made by the process of vinegar and tan, in which the lead has remained always solid during its transition from the blue to the white state; and hence consists of opaque particles.

A patent was obtained, in December, 1833, by John Baptiste Constantine Torassa, and others, for making white lead by agitating the granulated metal, or shot, in trays or barrels, along with water, and exposing the mixture of lead-dust and water to the air, to be oxidized and carbonated. It is said that upwards of 100,000_l._ have been expended at Chelsea, by a joint stock company, in a factory constructed for executing the preceding most operose and defective process; which has been, many years ago, tried without success in Germany. I am convinced that the whole of these recent projects for preparing white lead, are inferior in economy, and quality of produce, to the old Dutch process, which may be so arranged as to convert sheets of blue lead thoroughly into the best white lead, within the space of 12 days, at less expense of labour than by any other plan.

White lead, as obtained by precipitation from the acetate, subacetate, and subnitrate, is a true carbonate of the metal, consisting of one prime equivalent of lead 104, one of oxygen 8, and one of carbonic acid 22; whose sum is 134, the atomic weight of the compound; or, of lead, 77·6; oxygen, 6; carbonic acid, 16·4; in 100 parts. It has been supposed, by some authors, that the denser and better-covering white lead of Krems and Holland is a kind of subcarbonate, containing only 9 per cent. of carbonic acid; but this view of the subject does not accord with my researches.

WICK (_Mèche_, Fr.; _Docht_, Germ.); is the spongy cord, usually made of soft spun cotton threads, which by capillary action, draws up the oil in lamps, or the melted tallow or wax in candles, in small successive portions, to be burned. In common wax and tallow candles, the wick is formed of parallel threads; in the stearine candles, the wick is plaited upon the braiding machine, moistened with a very dilute sulphuric acid, and dried, whereby as it burns, it falls to one side and consumes without requiring to be snuffed; in the patent candles of Mr. Palmer, one-tenth of the wick is first imbued with subnitrate of bismuth ground up with oil, the whole is then bound round in the manner called _gimping_; and of this wick, twice the length of the intended candle is twisted double round a rod, like the _caduceus of Mercury_. This rod with its coil being inserted in the axis of the candle mould, is to be enclosed by pouring in the melted tallow; and when the tallow is set, the rod is to be drawn out at top, leaving the wick in the candle. As this candle is burned, the ends of the double wick stand out sideways beyond the flame; and the bismuth attached to the cotton being acted on by the oxygen of the atmosphere, causes the wick to be completely consumed, and, therefore, saves the trouble of snuffing it.

WINCING-MACHINE, is the English name of the dyer’s reel, which he suspends horizontally, by the ends of its iron axis in bearings, over the edge of his vat, so that the line of the axis, being placed over the middle partition in the copper, will permit the piece of cloth which is wound upon the reel, to descend alternately into either compartment of the bath, according as it is turned by hand to the right or the left. For an excellent self-acting or mechanical wince, see DYEING.

WINE, is the fermented juice of the grape. In the more southern states of Europe, the grapes, being more saccharine, afford a more abundant production of alcohol, and stronger wines, as exemplified in the best port, sherry, and madeira. The influence of solar heat upon the vines may, however, be mitigated by growing them to moderate heights on level ground, and by training them in festoons under the shelter of trees. In the more temperate climates, such as the district of Burgundy, the finer flavoured wines are produced; and there the vines are usually grown upon hilly slopes fronting the south, with more or less of an easterly or westerly direction, as on the Côte d’Or, at a distance from marshes, forests, and rivers, whose vapours might deteriorate the air. The plains of this district, even when possessing a similar or analogous soil, do not produce wines of so agreeable a flavour. The influence of temperature becomes very manifest in countries further north, where, in consequence of a few degrees of thermometric depression, the production of generous agreeable wine becomes impossible.

The land most favourable to the vine is light, easily permeable to water, but somewhat retentive by its composition; with a sandy subsoil, to allow the excess of moisture to drain readily off. Calcareous soils produce the highly esteemed wines of the Côte d’Or; a granitic debris forms the foundation of the lands where the Hermitage wines are grown; siliceous soil interspersed with flints furnishes the celebrated wines of Château-Neuf, Ferté, and La Gaude; schistose districts afford also good wine, as that called _la Malgue_. Thus we see that lands differing in chemical composition, but possessed of the proper physical qualities, may produce most agreeable wines; and so also may lands of like chemical and physical constitution produce various kinds of wine, according to their varied exposure. As a striking example of these effects, we may adduce the slopes of the hills which grow the wines of Montrachet. The insulated part towards the top furnishes the wine called _Chevalier Montrachet_, which is less esteemed, and sells at a much lower price, than the delicious wine grown on the middle height, called _true Montrachet_. Beneath this district, and in the surrounding plains, the vines afford a far inferior article, called _bastard Montrachet_. The opposite side of the hills produces very indifferent wine. Similar differences, in a greater or less degree, are observable relatively to the districts which grow the Pomard, Volnay, Beaune, Nuits, Vougeot, Chambertin, Romanée, &c. Every where it is found, that the reverse side of the hill, the summit, and the plain, although generally consisting of like soil, afford inferior wine to the middle southern slopes.

_Amelioration of the soil._--When the vine lands are too light or too dense, they may be modified, within certain limits, by introducing into them either argillaceous or siliceous matter. Marl is excellent for almost all grounds which are not previously too calcareous, being alike useful to open dense soils, and to render porous ones more retentive.

_Manure._--For the vine, as well as all cultivated plants, a manure supplying azotized or animal nutriment may be used with great advantage, provided care be taken to ripen it by previous fermentation, so that it may not, by absorption in too crude a state, impart any disagreeable odour to the grape; as sometimes happens to the vines grown in the vicinity of great towns, like Paris, and near Argenteuil. There is a compost used in France, called _animalized black_, of which from 1/3 to 1/2 of a litre (old English quart) serves sufficiently to fertilize the root of one vine, when applied every year, or two years. An excess of manure, in rainy seasons especially, has the effect of rendering the grapes large and insipid.

The ground is tilled at the same time as the manure is applied, towards the month of March; the plants are then dressed, and the props are inserted. The weakness of the plants renders this practice useful; but in some southern districts, the stem of the vine, when supported at a proper height, acquires after a while sufficient size and strength to stand alone. The ends of the props or poles are either dipped in tar, or charred, to prevent their rotting. The bottom of the stem must be covered over with soil, after the spring rains have washed it down. The principal husbandry of the vineyard consists in digging or ploughing to destroy the weeds, and to expose the soil to the influence of the air, during the months of May, June, and occasionally in August.

The vintage, in the temperate provinces, generally takes place about the end of September; and it is always deteriorated whenever the fruit is not ripe enough before the 15th or 20th of October; for, in this case, not only is the must more acid, and less saccharine, but the atmospherical temperature is apt to fall so low during the nights, as to obstruct more or less its fermentation into wine. The grapes should be plucked in dry weather, at the interval of a few days after they are ripe; being usually gathered in baskets, and transported to the vats in dorsels, sufficiently tight to prevent the juice from running out. Whenever a layer about 14 or 15 inches thick has been spread on the bottom of the vat, the treading operation begins, which is usually repeated after macerating the grapes for some time, when an incipient fermentation has softened the texture of the skin and the interior cells. When the whole bruised grapes are collected in the vat, the juice, by means of a slight fermentation, reacts, through the acidity thus generated, upon the colouring-matter of the husks, and also upon the tannin contained in the stones and the fruit-stalks. The process of fermentation is suffered to proceed without any other precaution, except forcing down from time to time the pellicles and pedicles floated up by the carbonic acid to the top; but it would be less apt to become acetous, were the mouths of the vats covered. With this view, M. Sebille Auger introduced with success his elastic bung in the manufacture of wine in the department of the Maine-et-Loire.

With whatever kind of apparatus the fermentation may have been regulated, as soon as it ceases to be tumultuous, and the wine is not sensibly saccharine or muddy, it must be racked off from the lees, by means of a spigot, and run into the ripening tuns. The marc being then gently squeezed in a press, affords a tolerably clear wine, which is distributed among the tuns in equal proportions; but the liquor obtained by stronger pressure, is reserved for the casks of inferior wine.

In the south of France the fermentation sometimes proceeds too slowly, on account of the must being too saccharine; an accident which is best counteracted by maintaining a temperature of about 65° or 68° F., in the tun-room. When the must, on the other hand, is too thin, and deficient in sugar, it must be partially concentrated by rapid boiling, before the whole can be made to ferment into a good wine. By boiling up a part of the must for this purpose, the excess of ferment is at the same time destroyed. Should this concentration be inconvenient, a certain proportion of sugar must be introduced, immediately after racking it off.

The specific gravity of must varies with the richness and ripeness of the grapes which afford it; being in some cases so low as 1·0627, and in others so high as 1·1283. This happens particularly in the south of France. In the district of the Necker in Germany, the specific gravity varies from 1·050 to 1·090; in Heidelberg, from 1·039, to 1·091; but it varies much in different years.

After the fermentation is complete, the vinous part consists of water, alcohol, a colouring-matter, a peculiar aromatic principle, a little undecomposed sugar, bitartrate and malate of potash, tartrate of lime, muriate of soda, and tannin; the latter substances being in small proportion.

It is known that a few green grapes are capable of spoiling a whole cask of wine, and therefore they are always allowed to become completely ripe, and even sometimes to undergo a species of slight fermentation, before being plucked, which completes the development of the saccharine principle. At other times the grapes are gathered whenever they are ripe, but are left for a few days on wicker-floors, to sweeten, before being pressed.

In general the whole vintage of the day is pressed in the evening, and the resulting must is received in separate vats. At the end usually of 6 or 8 hours, if the temperature be above 50° F., and if the grapes have not been too cold when plucked, a froth or scum is formed at the surface, which rapidly increases in thickness. After it acquires such a consistence as to crack in several places, it is taken off with a skimmer, and drained; and the thin liquor is returned to the vat. A few hours afterwards another coat of froth is formed, which is removed in like manner, and sometimes a third may be produced. The regular vinous fermentation now begins, characterized by air-bubbles rising up the sides of the staves, with a peculiar whizzing as they break at the surface. At this period all the remaining froth should be quickly skimmed off, and the clear subjacent must, be transferred into barrels, where it is left to ripen by a regular fermentation.

The white wines, which might be disposed to become stringy, from a deficient supply of tannin, may be preserved from this malady by a due addition of the footstalks of ripe grapes. The tannin, while it tends to preserve the wines, renders them also more easy to clarify, by the addition of white of egg, or isinglass.

The white wines should be racked off as soon as the first frosts have made them clear, and at the latest by the end of the February moon. By thus separating the wine from the lees, we avoid, or render of little consequence, the fermentation which takes place on the return of spring, and which, if too brisk, would destroy all its sweetness, by decomposing the remaining portion of sugar.

The characteristic odour possessed by all wines, in a greater or less degree, is produced by a peculiar substance, which possesses the characters of an essential oil. As it is not volatile, it cannot be confounded with the aroma of wine. When large quantities of wine are distilled, an oily substance is obtained towards the end of the operation. This may also be procured from the wine lees which are deposited in the casks after the fermentation has commenced. It forms one 40,000th part of the wine; and consists of a peculiar new acid, and ether, each of which has been called the _œnanthic_. The acid is analogous to the fatty acids, and the ether is liquid, but insoluble in water. The acid is perfectly white when pure, of the consistence of butter at 60°, melts with a moderate heat, reddens litmus, and dissolves in caustic and carbonated alkalis, as well as in alcohol and ether. Œnanthic ether is colourless, has an extremely strong smell of wine, which is almost intoxicating when inhaled, and a powerful disagreeable taste. _Liebig and Pelouze._

_Sparkling wines._--In the manufacture of these, black grapes of the first quality are usually employed, especially those gathered upon the vine called by the French _noirien_, cultivated on the best exposures. As it is important, however, to prevent the colouring-matter of the skin from entering into the wine, the juice should be squeezed as gently and rapidly as possible. The liquor obtained by a second and third pressing is reserved for inferior wines, on account of the reddish tint which it acquires. The marc is then mixed with the grapes of the red-wine vats.

The above nearly colourless must, is immediately poured into tuns or casks, till about three-fourths of their capacity are filled, when fermentation soon begins. This is allowed to continue under the control of the elastic bung, above mentioned, for about 15 days, and then three-fourths of the casks are filled up with wine from the rest. The casks are now closed by a bung secured with a piece of hoop iron nailed to two contiguous staves. The casks should be made of new wood, but not of oak--though old white wine casks are occasionally used.

In the month of January the clear wine is racked off, and is fined by a small quantity of isinglass dissolved in old wine of the same kind. Forty days afterwards a second fining is required. Sometimes a third may be useful, if the lees be considerable. In the month of May the clear wine is drawn off into bottles, taking care to add to each of them a small measure of what is called _liquor_, which is merely about 3 per cent. of a syrup made by dissolving sugar-candy in white wine. The bottles being filled, and their corks secured by packthread and wire, they are laid on their sides, in this month, with their mouths sloping downwards at an angle of about 20 degrees, in order that any sediment may fall into the neck. At the end of 8 or 10 days, the inclination of the bottles is increased, when they are slightly tapped, and placed in a vertical position; so that after the lees are all collected in the neck, the cork is partially removed for an instant, to allow the sediment to be expelled by the pressure of the gas. If the wine be still muddy in the bottles, along with a new dose of _liquor_, a small quantity of fining should be added to each, and the bottles should be placed again in the inverted position. At the end of two or three months, the sediment collected over the cork, is dexterously discharged; and if the wine be still deficient in transparency, the same process of fining must be repeated.

Sparkling wine (_vin mousseux_), prepared as above described, is fit for drinking usually at the end of from 18 to 30 months, according to the state of the seasons. It is in Champagne that the lightest, most transparent, and most highly flavoured wines, have been hitherto made. The breakage of the bottles in these sparkling wines amounts frequently to 30 per cent., a circumstance which adds greatly to their cost of production.

Weak wines of bad growths ought to be consumed within 12 or 15 months after being manufactured; and should be kept meanwhile in cool cellars. White wines of middling strength ought to be kept in casks constantly full, and carefully excluded from contact of air, and the racking off should be done as quickly as possible. As the most of them are injured by too much fermentation, this process should be so regulated as always to leave a little sugar undecomposed. It is useful to counteract the absorption of oxygen, and the consequent tendency to acidity, by burning a sulphur match in the casks into which they are about to be run. This is done by hooking the match to a bent wire, kindling and suspending it within the cask through the bung-hole. Immediately on withdrawing the match, the cask should be corked, if the wine be not ready for transfer. If the burning sulphur be extinguished on plunging it into the cask, it is a proof of the cask being unsound, and unfit for receiving the wine; in which case it should be well cleansed, first with lime-water, then with very dilute sulphuric acid, and lastly with boiling water.

Wine-cellars ought to be dry at bottom, floored with flags, have windows opening to the north, be so much sunk below the level of the adjoining ground as to possess a nearly uniform temperature in summer and winter; and be at such a distance from a frequented highway or street as not to suffer vibration from the motion of carriages.

Wines should be racked off in cool weather; the end of February being the fittest time for light wines. Strong wines are not racked off till they have stood a year or eighteen months upon the lees, to promote their slow or insensible fermentation. A syphon well managed serves better than a faucet to draw off wine clear from the sediment. White wines, before being bottled, should be fined with isinglass; red wines are usually fined with whites of eggs beat up into a froth, and mixed with two or three times their bulk of water. But some strong wines, which are a little harsh from excess of tannin, are fined with a little sheep or bullock’s blood. Occasionally a small quantity of sweet glue is used for this purpose.

_The following maladies of wines_, are certain accidental deteriorations, to which remedies should be speedily applied.

_La-pousse_ (pushing out of the cask), is the name given to a violent fermentative movement, which occasionally supervenes after the wine has been run off into the casks. If these have been tightly closed, the interior pressure may increase to such a degree as to burst the hoops, or cause the seams of the staves or ends to open. The elastic bungs already described, will prevent the bursting of the casks; but something must be done to repress the fermentation, lest it should destroy the whole of the sugar, and make the wine unpalatably harsh. One remedy is, to transfer the wine into a cask previously fumigated with burning sulphur; another is, to add to it about one thousandth part of sulphite of lime; and a third, and perhaps the safest, is to introduce half a pound of mustard-seed into each barrel. At any rate the wines should be fined whenever the movements are allayed, to remove the floating ferment which has been the cause of the mischief.

_Turning sour._--The production of too much acid in a wine, is a proof of its containing originally too little alcohol, of its being exposed too largely to the air, or to vibrations, or to too high a temperature in the cellar. The best thing to be done in this case is, to mix it with its bulk of a stronger wine in a less advanced state, to fine the mixture, to bottle it, and to consume it as soon as possible, for it will never prove a good keeping wine. This _distemper_ in wines formerly gave rise to the very dangerous practice of adding litharge as a sweetener; whereby a quantity of acetate or sugar of lead was formed in the liquor, productive of the most deleterious consequences to those who drunk of it. In France, the regulations of police, and the enlightened _surveillance_ of the council of salubrity, have completely put down this gross abuse. The saturation of the acid by lime and other alkaline bases has generally a prejudicial effect, and injures more or less the vinous flavour and taste.

_Ropiness or viscidity of wines._--The cause of this phenomenon, which renders wine unfit for drinking, was altogether unknown, till M. François, an apothecary of Nantes, demonstrated that it was owing to an azotized matter, analogous to _gliadine_ (gluten); and in fact it is the white wines, especially those which contain the least tannin, which are subject to this malady. He also pointed out the proper remedy, in the addition of tannin under a rather agreeable form, namely, the bruised berries of the mountain-ash (_sorbier_), in a somewhat unripe state; of which one pound, well stirred in, is sufficient for a barrel. After agitation, the wine is to be left in repose for a day or two, and then racked off. The tannin by this time will have separated the azotized matter from the liquor, and removed the ropiness. The wine is to be fined and bottled off.

_The taste of the cask_, which sometimes happens to wine put into casks which had remained long empty, is best remedied by agitating the wine for some time with a spoonful of olive oil. An essential oil, the chief cause of the bad taste, combines with the fixed oil, and rises with it to the surface.

According to a statement in the _Dictionnaire Technologique_, the annual produce of a hectare of vineyard, upon the average of 113 years, in the district of Volnay, is 1779 litres, which fetch 0·877 francs each, or 200 francs the piece of 228 litres, amounting in all to 1672 francs. Deducting for expenses and taxes (_contributions_) 572 francs, there remain 1100 francs of net proceeds; and as the value of the capital may be estimated at 23,000 francs, the profit turns out to be no more than 5 per cent. The net proceeds in the growths of Beaune, Nuits, &c., does not exceed 600 francs per hectare (2·4 acres), and therefore is equivalent to only 2-1/2 per cent. upon the capital.

The quantity of alcohol contained in different wines, has been made the subject of elaborate experiments by Brande and Fontenelle; but as it must evidently vary with different seasons, the results can be received merely as approximative. The only apparatus required for this research, is a small still and refrigeratory, so well fitted up as to permit none of the spirituous vapours to be dissipated. The distilled liquor should be received in a glass tube, graduated into one hundred measures, of such capacity as to contain the whole of the alcohol which the given measure of wine employed is capable of yielding. In the successive experiments, the quantity of wine used, and of spirit distilled over, being the same in volume, the relative densities of the latter will show at once the relative strengths of the wines. A very neat small apparatus has been contrived for the purpose of analyzing wines in this manner, by M. Gay Lussac. It is constructed, and sold at a moderate price, by M. Collardeau, No. 56, Rue Faubourg St. Martin, Paris. The proportion given by Brande (Table I.), has been reduced to the standard of absolute alcohol by Fesser; and that by Fontenelle (Table II.), to the same standard by Schubarth; as in the following tables:--

TABLE I.

+------------------+---------+------------------+ | | | 100 measures, | | | |contain at 60° F. | |Name of the Wine. |Sp. grav.+---------+--------+ | | | Alcohol |Absolute| | | |of 0·825.|alcohol.| +------------------+---------+---------+--------+ |Port Wine | 0·97616 | 21·40 | 19·82 | | Do. | 0·97200 | 25·83 | 23·92 | | Mean| 0·97460 | 23·49 | 21·75 | |Madeira | 0·97810 | 19·34 | 17·91 | | Do. | 0·97333 | 21·42 | 22·61 | |Sherry | 0·97913 | 18·25 | 17·00 | | Do. | 0·97700 | 19·83 | 18·37 | |Bordeaux, Claret | 0·97410 | 12·91 | 11·95 | | Do. | 0·97092 | 16·32 | 15·11 | |Calcavella | 0·97920 | 18·10 | 16·76 | |Lisbon | 0·97846 | 18·94 | 17·45 | |Malaga | 0·98000 | 17·26 | 15·98 | |Bucellas | 0·97890 | 18·49 | 17·22 | |Red Madeira | 0·97899 | 18·40 | 17·04 | |Malmsey | 0·98090 | 16·40 | 15·91 | |Marsala | 0·98190 | 15·26 | 14·31 | | Do. | 0·98000 | 17·26 | 15·98 | |Champagne (rose) | 0·98608 | 11·30 | 10·46 | | Do. (white) | 0·98450 | 12·80 | 11·84 | |Burgundy | 0·98300 | 14·53 | 13·34 | | Do. | 0·98540 | 11·95 | 11·06 | |White Hermitage | 0·97990 | 17·43 | 16·14 | |Red do. | 0·98495 | 12·32 | 11·40 | |Hock | 0·98290 | 14·37 | 13·31 | | Do. | 0·98873 | 8·88 | 8·00 | |Vin de Grave | 0·98450 | 12·80 | 11·84 | |Frontignac | 0·98452 | 17·79 | 11·84 | |Côte-Rotí | 0·98495 | 12·27 | 11·36 | |Roussillon | 0·98005 | 17·24 | 15·96 | |Cape Madeira | 0·97924 | 18·11 | 16·77 | |Muscat | 0·97913 | 18·25 | 17·00 | |Constantia | 0·97770 | 19·75 | 18·29 | |Tinto | 0·98399 | 13·30 | 12·32 | |Schiraz | 0·98176 | 15·52 | 14·35 | |Syracuse | 0·98200 | 15·28 | 14·15 | |Nice | 0·98263 | 14·63 | 13·64 | |Tokay | 0·98760 | 9·88 | 9·15 | |Raisin wine | 0·97205 | 25·77 | 23·86 | |Drained grape wine| 0·97925 | 18·11 | 16·77 | |Lachrymæ Christi | -- | 19·70 | 18·24 | |Currant wine | 0·97696 | 20·55 | 19·03 | |Gooseberry wine | 0·98550 | 11·84 | 10·96 | |Elder wine } | | | | |Cyder } | 0·98760 | 9·87 | 9·14 | |Perry } | | | | |Brown Stout | 0·99116 | 6·80 | 6·30 | |Ale | 0·98873 | 8·88 | 8·00 | |Porter | -- | 4·20 | 3·89 | |Rum | 0·93494 | 53·68 | 49·71 | |Hollands | 0·93855 | 51·60 | 47·77 | |Scotch whiskey | -- | 54·32 | 50·20 | |Irish whiskey | -- | 53·90 | 49·91 | +------------------+---------+---------+--------+

TABLE II.

+--------------------------------+--------+ | |Absolute| | Name of the Wine. |alcohol.| +--------------------------------+--------+ |_Roussillon (Eastern Pyrenees.)_| | |Rive-saltes 18 yrs. old | 9·156 | |Banyulls 18 | 9·223 | |Collyouvre 15 | 9·080 | |Salces 10 | 8·580 | | | | | _Department of the Aude._ | | |Fitou and Leucaté 10 | 8·568 | |Lapalme 10 | 8·790 | |Sijeau 8 | 8·635 | |Narbonne 8 | 8·379 | |Lezignan 10 | 8·173 | |Mirepeisset 10 | 8·589 | |Carcasonne 8 | 7·190 | | | | | _Department of l’Herault._ | | |Nissau 9 | 7·896 | |Beziers 8 | 7·728 | |Montagnac 10 | 8·108 | |Mèze 10 | 7·812 | |Montpellier 5 | 7·413 | |Lunel 8 | 7·564 | |Frontignan 5 | 7·098 | |Red Hermitage 4 | 5·838 | |White do. | 7·056 | |Burgundy 4 | 6·195 | |Grave 3 | 5·838 | |Champagne (sparkling) | 5·880 | | Do. white do. | 5·145 | | Do. rose | 4·956 | |Bordeaux | 6·186 | |Toulouse | 5·027 | +--------------------------------+--------+

WINE, FAMILY, may be made by the following recipe:--Take black, red, white currants, ripe cherries (black hearts are the best), and raspberries, of each an equal quantity. To 4 pounds of the mixed fruit, well bruised, put 1 gallon of clear soft water; steep three days and nights, in open vessels, frequently stirring up the magma; then strain through a hair sieve; press the residuary pulp to dryness, and add its juice to the former. In each gallon of the mixed liquors dissolve 3 pounds of good yellow muscovado sugar; let the solution stand other three days and nights, frequently skimming and stirring it up; then tun it into casks, which should remain full, and purging at the bung-hole, about two weeks. Lastly, to every 9 gallons, put 1 quart of good Cognac brandy (but not the drugged imitations made in London with grain whiskey), and bung down. If it does not soon become fine, a steeping of isinglass may be stirred into the liquid, in the proportion of about half an ounce to 9 gallons. I have found that the addition of an ounce of cream of tartar to each gallon of the fermentable liquor, improves the quality of the wine, and makes it resemble more nearly the produce of the grape.

WINE-STONE, is the deposit of crude tartar, called argal, which settles on the sides and bottoms of wine casks.

WIRE-DRAWING. (_Tréfilerie_, Fr.; _Draht-ziehen_, _Drahtzug_, Germ.) When an oblong lump of metal is forced through a series of progressively diminishing apertures in a steel plate, so as to assume in its cross section the form and dimensions of the last hole, and to be augmented in length at the expense of its thickness, it is said to be wire-drawn. The piece of steel called the _draw-plate_ is pierced with a regular gradation of holes, from the largest to the smallest; and the machine for overcoming the lateral adhesion of the metallic particles to one another, is called the _draw-bench_. The pincers which lay hold of the extremity of the wire, to pull it through the successive holes, are adapted to bite it firmly, by having the inside of the jaws, cut like a file. For drawing thick rods of gilt silver down into stout wire, the hydraulic press has been had recourse to with advantage.

_Fig._ 1202. represents a convenient form of the draw-bench, where the power is applied by a toothed wheel, pinion, and rack-work, moved by the hands of one or two men working at a winch; the motion being so regulated by a fly-wheel, that it does not proceed in fits and starts, and cause inequalities in the wire. The metal requires to be annealed, now and then, between successive drawings, otherwise it would become too hard and brittle for further extension. The reel upon which it is wound is sometimes mounted in a cistern of sour small beer, for the purpose of clearing off, or loosening at least, any crust of oxide formed in the annealing, before the wire enters the draw-plate.

When, for very accurate purposes of science or the arts, a considerable length of uniform wire is to be drawn, a plate with one or more jewelled holes, that is, filled with one or more perforated rubies, sapphires, or chrysolites, can alone be trusted to, because the holes even in the best steel become rapidly wider by the abrasion. Through a hole in a ruby 0·0033 of an inch in diameter, a silver wire 170 miles long has been drawn, which possessed at the end, the very same section as at the beginning; a result determined by weighing portions of equal length, as also by measuring it with a micrometer. The hole in an ordinary draw-plate of soft steel becomes so wide, by drawing 14,000 fathoms of brass wire, that it requires to be narrowed before the original sized wire can be again obtained.

Wire, by being diminished one-half, one-third, one-fourth, &c., in diameter, is augmented in length respectively, four, nine, sixteen times, &c. The speed with which it may be prudently drawn out, depends upon the ductility and tenacity of the metal; but may be always increased the more the wire becomes attenuated, because its particles progressively assume more and more of the filamentous form, and accommodate themselves more readily to the extending force. Iron and brass wires, of 0·3 inch in diameter, bear drawing at the rate of from 12 to 15 inches per second; but when of 0·025 (1/40) of an inch, at the rate of from 40 to 45 inches in the same time. Finer silver and copper wire may be extended from 60 to 70 inches per second.

By enclosing a wire of platinum within one of silver ten times thicker, and drawing down the compound wire till it be 1/300 of an inch, a wire of platinum of 1/3000 of an inch, will exist in its centre, which may be obtained apart, by dissolving the silver away in nitric acid. This pretty experiment was first made by Dr. Wollaston.

The French draw-plates are so much esteemed, that one of the best of them used to be sold in this country, during the late war, for its weight in silver. The holes are formed with a steel punch; being made large on that side where the wire enters, and diminishing with a regular taper to the other side. In the act of drawing, they must be well supplied with grease for the larger kinds of wire, and with wax for the smaller.

WOAD (_Vouëde_, _Pastel_, Fr.; _Waid_, Germ; _Isatis tinctoria_, Linn.); the _glastum_ of the antient Gauls and Germans; is an herbaceous plant which was formerly much cultivated, as affording a permanent blue dye, but it has been in modern times well nigh superseded by _indigo_. Pliny says, “A certain plant which resembles _plantago_, called _glastum_, is employed by the women and girls in Great Britain for dyeing their bodies all over, when they assist at certain religious ceremonies; they have then the colour of Ethiopians.”--_Hist. Nat._ cap. xxii. § 2.

When the arts, which had perished with the Roman empire, were revived, in the middle ages, woad began to be generally used for dyeing blue, and became an object of most extensive cultivation in many countries of Europe. The environs of Toulouse and Mirepoix, in Upper Languedoc, produced annually 40,000,000 pounds of the prepared woad, or pastel, of which 200,000 bales were consumed at Bordeaux. Beruni, a rich manufacturer of this drug, became surety for the payment of the ransom of his king, Francis I., then the prisoner of Charles V. in Spain.

The leaves of woad are fermented in heaps, to destroy certain vegetable principles injurious to the beauty of the dye, as also to elaborate the indigoferous matter present, before they are brought into the market; but they should be carefully watched during this process. Whenever the leaves have arrived at maturity, a point judged of very differently in different countries, they are stripped off the plant, a cropping which is repeated as often as they shoot, being three or four times in Germany, and eight or ten times in Italy. The leaves are dried as quickly as possible, but not so much as to become black; and they are ground before they get quite dry. The resulting paste is laid upon a sloping pavement, with gutters for conducting the juice which exudes into a tank; the heap being tramped from time to time, to promote the discharge of the juice. The woad ferments, swells, and cracks in many places, which fissures must be closed; the whole being occasionally watered. The fermentation is continued for twenty or thirty days, in cold weather; and if the leaves have been gathered dry, as in Italy, for four months. When the fermented heap has become moderately dry, it is ground again, and put up in cakes of from one to three pounds; which are then fully dried, and packed up in bundles for the market. Many dyers subject the pastel to a second fermentation.

1,600 square toises (fathoms) of land afford in two cuttings at least 19,000 pounds of leaves, of which weight four-fifths are lost in the fermentation, leaving 3,880 pounds of pastel, in loaves or cakes. When good, it has rather a yellow, or greenish-yellow, than a blue colour; it is light, and slightly humid; it gives to paper a pale-green trace; and improves by age, in consequence of an obscure fermentation; for if kept four years, it dyes twice as much as after two years. According to Hellot, 4 pounds of Guatimala indigo produce the same effect as 210 pounds of the pastel of Albi. At Quins, in Piedmont, the dyers estimate that 6 pounds of indigo are equivalent to 300 of pastel; but Chaptal thinks the indigo underrated.

Pastel will dye blue of itself, but it is commonly employed as a fermentative addition to the proper blue vat, as described under INDIGO.

Fresh woad, analyzed by Chevreul, afforded, in 100 parts, 65·4 of juice. After being steeped in water, the remaining mass yielded, on expression, 29·65 of liquid; being in whole, 95·05 parts, leaving 4·95 of ligneous fibre. The juice, by filtration, gave 1·95 of green fecula. 100 parts of fresh woad, when dried, are reduced to 13·76 parts. Alcohol, boiled upon dry woad, deposits, after cooling, indigo in microscopic needles; but these cannot be separated from the vegetable albumine, which retains a greenish-gray colour.

WOLFRAM, is the native tungstate of iron and manganese, a mineral which occurs in primitive formations, along with the ores of tin, antimony, and lead, in the Bohemian Erzgebirge, in Cornwall, Switzerland, North America, &c. It is used by chemists for obtaining tungstic acid and tungsten.

WOOD (_Bois_, Fr.; _Holz_, Germ.); is the hard but porous tissue between the pith and the bark of trees and shrubs, through which the chief part of the juices are conducted from the root towards the branches and leaves, during the life of the vegetable. The ligneous fibre is the substance which remains, after the plant has been subjected to the solvent action of ether, alcohol, water, dilute acids, and caustic alkaline lyes. It is considered by chemists that dry timber consists, on an average, of 96 parts of fibrous, and 4 of soluble matter, in 100; but that these proportions vary somewhat with the seasons, the soil, and the plant. All kinds of wood sink in water, when placed in a basin of it under the exhausted receiver of an air-pump; showing their specific gravity to be greater than 1·000. That of fir and maple is stated, by chemical authors, to be 1·46; and that of oak and beech, at 1·53; but I believe them to have all the same spec. grav. as the fibre of flax; namely, 1·50, as determined by me some years ago.[71]

[71] “From the small difference found by experiment between the specific gravity of flax (1·50), and of cotton (1·47), I am inclined to think that the density of both may be considered to be equal.” or 1·50.--_Philosophy of Manufactures_, 2d edition, pp. 97, 98, 99.

Wood becomes snow-white, when exposed to the action of chlorine; digested with sulphuric acid, it is transformed first into gum, and, by ebullition with water, afterwards into grape-sugar; with concentrated nitric acid, it grows yellow, loses its coherence, falls into a pulverulent mass, but eventually dissolves, and is converted into oxalic acid; with strong caustic alkaline lyes, in a hot state, it swells up excessively, dissolves into a homogeneous liquid, and changes into a blackish-brown mass, containing oxalic and acetic acids.

The composition of wood has been examined by Gay Lussac and Thenard, and Dr. Prout. The first two chemists found it to consist, in 100 parts, of--

Oak. Beech. Carbon 52·53 51·45 Hydrogen 5·69 5·82 Oxygen 41·78 42·73

According to Dr. Prout, the oxygen and hydrogen are in the exact proportions to form water. Willow contains 50, and box 49·8 per cent. of carbon; each containing, therefore, very nearly 44·444 of oxygen, and 5·555 of hydrogen. In the analyses of Gay Lussac and Thenard, there is a great excess of hydrogen above what the oxygen requires to form water. Authenrieth stated, some years ago, that he found that fine sawdust, mixed with a sufficient quantity of wheat flour, made a coherent dough with water, which formed an excellent food for pigs; apparently showing that the digestive organs of this animal could operate the same sort of change upon wood as sulphuric acid does.

TABLE of the DISTILLATION of ONE POUND of WOOD, dried, at 86° Fahr.

+-------------------------+----------+-----------+---------+---------+ | Name of the wood. |Weight of |One ounce |Weight of|Weight of| | |wood acid.|of the acid|the com- |the char-| | | |saturates |bustible |coal. | | | |of carbon- |oil. | | | | |ate of | | | | | |potash. | | | +-------------------------+----------+-----------+---------+---------+ | | _Ounces._| _Grains._ |_Ounces._|_Ounces._| |White birch | 7 | 44 | 1-1/4 | 3-3/4 | |Red beech | 7 | 44 | 1-1/2 | 3-3/4 | |Prick wood (spindle tree)| 7-1/2 | 40 | 1-3/4 | 3-1/2 | |Large leaved linden | 6-3/4 | 41 | 2 | 3-3/4 | |Red or scarlet oak | 7 | 40 | 1-1/2 | 4-1/4 | |White beech | 6-1/2 | 40 | 1-3/4 | 3-3/4 | |Common ash | 7-1/2 | 34 | 1-1/2 | 3-1/2 | |Horse chestnut | 7-1/2 | 31 | 1-1/2 | 3-1/2 | |Italian poplar | 7-1/4 | 30 | 1-1/2 | 3-3/4 | |Silver poplar | 7-1/4 | 30 | 1-1/4 | 3-3/4 | |White willow | 7-1/4 | 28 | 1-1/2 | 3-1/2 | |Root of the sassafras | | | | | |laurel | 6-3/4 | 29 | 1-3/4 | 4-1/4 | |Wild service tree | 7 | 28 | 1-3/4 | 3-1/2 | |Basket willow | 8 | 27 | 1-1/2 | 3-1/2 | |Dogberry tree | 7 | 27 | 2 | 3-1/2 | |Buckthorn | 7-1/2 | 26 | 1-1/2 | 3-1/2 | |Logwood | 7-3/4 | 26 | 1-1/2 | 4 | |Alder | 7-1/4 | 22 | 1-1/2 | 3-1/2 | |Juniper | 7-1/4 | 23 | 1-3/4 | 3-1/2 | |White fir (deal) | 6-1/2 | 23 | 2-1/4 | 3-1/2 | |Common pine wood | 6-3/4 | 22 | 1-3/4 | 3-1/2 | |Savine tree | 7 | 20 | 1-3/4 | 3-3/4 | |Red deal (pine) | 6-1/2 | 18 | 2-1/4 | 3-3/4 | |Guiac wood | 6 | 16 | 2-1/2 | 4-1/4 | +-------------------------+----------+-----------+---------+---------+

WOOF, is the same as WEFT.

WOOLLEN MANUFACTURE. In reference to textile fabrics, sheep’s wool is of two different sorts, the short and the long stapled; each of which requires different modes of manufacture in the preparation and spinning processes, as also in the treatment of the cloth after it is woven, to fit it for the market. Each of these is, moreover, distinguished in commerce by the names of fleece wools and dead wools, according as they have been shorn at the usual annual period from the living animal, or are cut from its skin after death. The latter are comparatively harsh, weak, and incapable of imbibing the dyeing principles, more especially if the sheep has died of some malignant distemper. The annular pores, leading into the tubular cavities of the filaments, seem, in this case, to have shrunk and become obstructed. The time of year for sheep-shearing most favourable to the quality of the wool, and the comfort of the animal, is towards the end of June and beginning of July;--the period when Lord Leicester holds his celebrated rural fête for that interesting purpose.

The wool of the sheep has been surprisingly improved, by its domestic culture. The _mouflon_ (_Ovis aries_), the parent stock from which our sheep is undoubtedly derived, and which is still found in a wild state upon the mountains of Sardinia, Corsica, Barbary, Greece, and Asia Minor, has a very short and coarse fleece, more like hair than wool. When this animal is brought under the fostering care of man, the rank fibres gradually disappear; while the soft wool round their roots, little conspicuous in the wild animal, becomes singularly developed. The male most speedily undergoes this change, and continues ever afterwards to possess far more power in modifying the fleece of the offspring, than the female parent. The produce of a breed from a coarse-woolled ewe, and a fine-woolled ram, is not of a mean quality between the two, but half-way nearer that of the sire. By coupling the female thus generated, with such a male as the former, another improvement of one-half will be obtained, affording a staple three-fourths finer than that of the grandam. By proceeding inversely, the wool would be as rapidly deteriorated. It is, therefore, a matter of the first consequence in wool husbandry, to exclude from the flock all coarse-fleeced rams.

Long wool is the produce of a peculiar variety of sheep, and varies in the length of its fibres from 3 to 8 inches. Such wool is not carded like cotton, but combed like flax, either by hand or appropriate machinery. Short wool is seldom longer than 3 or 4 inches; it is susceptible of carding and felting, by which processes the filaments become first convoluted, and then densely matted together. The shorter sorts of the combing wool are used principally for hosiery, though of late years the finer kinds have been extensively worked up into merino and mousseline-de-laine fabrics. The longer wools of the Leicestershire breed are manufactured into hard yarns, for worsted pieces, such as waistcoats, carpets, bombasines, poplins, crapes, &c.

The wool of which good broad cloth is made, should be not only shorter, but, generally speaking, finer and softer than the worsted wools, in order to fit them for the fulling process. Some wool-sorters and wool-staplers acquire by practice great nicety of discernment in judging of wools by the touch and traction of the fingers. Two years ago, I made a series of observations upon different wools, and published the results. The filaments of the finer qualities varied in thickness from 1/1100 to 1/1500 of an inch; their structure is very curious, exhibiting, in a good achromatic microscope, at intervals of about 1/300 of an inch, a series of serrated rings, imbricated towards each other, like the joints of _Equisetum_, or rather like the scaly zones of a serpent’s skin. See _Philosophy of Manufactures_, _figs._ 11, 12., page 91. second edition.

There are four distinct qualities of wool upon every sheep; the finest being upon the spine, from the neck to within 6 inches of the tail, including one-third of the breadth of the back; the second covers the flanks between the thighs and the shoulders; the third clothes the neck and the rump; and the fourth extends upon the lower part of the neck and breast down to the feet, as also upon a part of the shoulders and the thighs, to the bottom of the hind quarter. These should be torn asunder, and sorted, immediately after the shearing.

The harshness of wools is dependent not solely upon the breed of the animal, or the climate, but is owing to certain peculiarities in the pasture, derived from the soil. It is known, that in sheep fed upon chalky districts, wool is apt to get coarse; but in those upon a rich loamy soil, it becomes soft and silky. The ardent sun of Spain renders the fleece of the Merino breed harsher than it is in the milder climate of Saxony. Smearing sheep with a mixture of tar and butter, is deemed favourable to the softness of their wool.

All wool, in its natural state, contains a quantity of a peculiar potash-soap, secreted by the animal, called in this country the _yolk_; which may be washed out by water alone, with which it forms a sort of lather. It constitutes from 25 to 50 per cent. of the wool, being most abundant in the Merino breed of sheep; and however favourable to the growth of the wool on the living animal, should be taken out soon after it is shorn, lest it injure the fibres by fermentation, and cause them to become hard and brittle. After being washed in water, somewhat more than lukewarm, the wool should be well pressed, and carefully dried. England grows annually about 1,000,000 packs of wool, and imports 100,000 bags.

Wool imported into the United Kingdom, in 1836, 64,239,977 lbs.; in 1837, 48,356,121 lbs. Retained for home consumption, in 1836, 60,724,795 lbs.; in 1837, 43,148,297 lbs. Duty received, in 1836, _£_190,075; in 1837, _£_118,519.

Having premised these general observations on wool, I shall now proceed to treat of its manufacture, beginning with that of wool-combing, or

THE WORSTED MANUFACTURE.

In this branch of business, a long stapled and firm fibre is required to form a smooth level yarn, little liable to shrink, curl, or felt in weaving and finishing the cloth. It must not be entangled by carding, but stretched in lines as parallel as possible, by a suitable system of _combing_, manual or mechanical.

When the long wool is brought into the worsted factory, it is first of all washed by men with soap and water, who are paid for their labour by the piece, and are each assisted by a boy, who receives the wool as it issues from between the drying _squeezers_ (see BLEACHING). The boy carries off the wool in baskets, and spreads it evenly upon the floor of the drying-room, usually an apartment over the boilers of the steam-engine, which is thus economically heated to the proper temperature. The health of the boys employed in this business is found to be not at all injured.

The wool, when properly dried, is transferred to a machine called the _plucker_, which is always superintended by a boy of 12 or 14 years of age, being very light work. He lays the tresses of wool pretty evenly upon the feed-apron, or table covered with an endless moving web of canvas, which, as it advances, delivers the ends of the long tufts to a pair of fluted rollers, whence it is introduced into a fanning apparatus, somewhat similar to the _willow_ employed in the cotton manufacture, which see. The filaments are turned out, at the opposite end of this winnowing machine, straightened, cleaned, and ready for the combing operation. According to the old practice of the trade, and still for the finer descriptions of the long staple, according to the present practice, the wool is carded by hand. This is far more severe labour than any subservient to machinery, and is carried on in rooms rendered close and hot by the number of stoves requisite to heat the combs, and so enable them to render the fibres soft, flexible, and elastic. This is a task at which only robust men are engaged. They use three implements: 1. a pair of combs for each person; 2. a post, to which one of the combs can be fixed; 3. a comb-pot, or small stove for heating the teeth of the combs. Each comb is composed either of two or three rows of pointed tapering steel teeth, _b_, _fig._ 1203., disposed in two or three parallel planes, each row being a little longer than the preceding. They are made fast at the roots to a wooden stock or head _c_, which is covered with horn, and has a handle _d_, fixed into it at right angles to the lines of the teeth. The spaces between these two or three planes of teeth, is about one-third of an inch at their bottoms, but somewhat more at their tips. The first combing, when the fibres are most entangled, is performed with the two-row toothed combs; the second or finishing combing, with the three-row toothed.

In the workshop a post is planted (_fig._ 1204.) upright, for resting the combs occasionally upon, during the operation. An iron stem _g_, projects from it horizontally, having its end turned up, so as to pass through a hole in the handle of the comb. Near its point of insertion into the post, there is another staple point _h_, which enters into the hollow end of the handle; which, between these two catches, is firmly secured to the post. The stove is a very simple affair, consisting merely of a flat iron plate, heated by fire or steam, and surmounted with a similar plate, at an interval sufficient to allow the teeth to be inserted between them at one side, which is left open, while the space between their edges, on the other sides, is closed to confine the heat.

In combing the wool, the workman takes it up in tresses of about four ounces each, sprinkles it with oil, and rolls it about in his hands, to render all the filaments equally unctuous. Some harsh dry wools require one-sixteenth their weight of oil, others no more than a fortieth. He next attaches a heated comb to the post, with its teeth pointed upwards, seizes one-half of the tress of wool in his hands, throws it over the teeth, then draws it through them, and thus repeatedly: leaving a few straight filaments each time upon the comb. When the comb has in this way collected all the wool, it is placed with its points inserted into the cell of the stove, with the wool hanging down outside, exposed to the influence of the heat. The other comb, just removed in a heated state from the stove, is planted upon the post, and furnished in its turn with the remaining two-ounce tress of wool; after which it supplants the preceding at the stove. Having both combs now hot, he holds one of them with his left hand over his knee, being seated upon a low stool, and seizing the other with his right hand, he combs the wool upon the first, by introducing the teeth of one comb into the wool stuck in the other, and drawing them through it. This manipulation is skilfully repeated, till the fibres are laid truly parallel, like a flat tress of hair. It is proper to begin by combing the tips of the tress, and to advance progressively, from the one end towards the other, till at length the combs are worked with their teeth as closely together as is possible, without bringing them into collision. If the workman proceeded otherwise, he would be apt to rupture the filaments, or tear their ends entirely out of one of the combs. The flocks left at the end of the process, because they are too short for the comber to grasp them in his hand, are called _noyls_. They are unfit for the worsted spinner, and are reserved for the coarse cloth manufacture.

The wool finally drawn off from the comb, though it may form a uniform tress of straight filaments, must yet be combed again at a somewhat lower temperature, to prepare it perfectly for the spinning operation. From ten to twelve slivers are then arranged in one parcel.

To relieve the workman from this laborious and not very salubrious task, has been the object of many mechanical inventions. One of these, considerably employed in this country and in France, is the invention of the late Mr. John Collier, of Paris, for which a patent was obtained in England, under the name of John Platt, of Salford, in November, 1827. It consists of two comb-wheels, about ten feet in diameter, having hollow iron spokes filled with steam, in order to keep the whole apparatus at a proper combing heat. The comb forms a circle, made fast to the periphery of the wheel, the teeth being at right angles to the plane of the wheel. The shafts of the two wheels are mounted in a strong frame of cast iron; not, however, in horizontal positions, but inclined at acute angles to the horizon, and in planes crossing each other, so that the teeth of one circular comb sweep with a steady obliquity over the teeth of the other, in a most ingenious manner, with the effect of combing the tresses of wool hung upon them. The proper quantity of long wool, in its ordinary state, is stuck in handfuls upon the wheel, revolving slowly, by a boy, seated upon the ground at one side of the machine. Whenever the wheel is dressed, the machine is made to revolve more rapidly, by shifting its driving-band on another pulley; and it is beautiful to observe the delicacy and precision with which it smoothes the tangled tress. When the wools are set in rapid rotation, the loose ends of the fleece, by the centrifugal force, are thrown out, in the direction of radii, upon the teeth of the other revolving comb-wheel, so as to be drawn out and made truly straight. The operation commences upon the tips of the tresses, where the wheels, by the oblique posture of their shafts, are at the greatest distance apart; but as the planes slowly approach to parallelism, the teeth enter more deeply into the wool, till they progressively comb the whole length of its fibres. The machines being then thrown out of geer, the teeth are stript of the tresses by the hand of the attendant; the _noyls_, or short refuse wool, being also removed, and kept by itself.

This operation being one of simple superintendence, not of handicraft effort and skill, like the old combing of long wool, is now performed by boys or girls of 13 and 14 years of age; and places in a striking point of view the influence of automatic mechanism, in so embodying dexterity and intelligence in a machine, as to render the cheap and tractable labour of children a substitute for the high-priced and often refractory exertions of workmen too prone to capricious combinations. The chief precaution to be taken with this machine, is to keep the steam-joints tight, so as not to wet the apartments, and to provide due ventilation for the operatives.

The following machine, patented by James Noble, of Halifax, worsted-spinner, in February, 1834, deserves particular notice, as its mode of operation adapts it well also for heckling flax. In _fig._ 1205. the internal structure is exhibited. The frame-work _a_, _a_, supports the axle of a wheel _b_, _b_, in suitable bearings on each side. To the face of this wheel is affixed the eccentric or heart-wheel cam _c_, _c_. On the upper part of the periphery of this cam or heart-wheel, a lever _d_, _d_, bears merely by its gravity; one end of which lever is connected by a joint to the crank _e_. By the rotation of the crank _e_, it will be perceived that the lever _d_, will be slidden to and fro on the upper part of the periphery of the eccentric or heart-wheel cam _c_, the outer end of the lever _d_, carrying the upper or working comb or needle-points _f_, as it moves, performing an elliptical curve, which curve will be dependent upon the position of the heart-wheel cam _c_, that guides it. A movable frame _g_, carries a series of points _h_, which are to constitute the lower comb or frame of needles. Into these lower needles the rough uncombed wool is to be fed by hand, and to be drawn out and combed straight by the movements of the upper or working comb.

As it is important, in order to prevent waste, that the ends of the wool should be first combed out, and that the needle-points should be made to penetrate the wool progressively, the movable frame _g_, is in the first instance placed as far back as possible; and the action of the lever _d_, during the whole operation, is so directed by the varying positions of the cam-wheel, as to allow the upper comb to enter at first a very little way only into the wool; but as the operation of combing goes on, the frame with the lower combs is made to advance gradually, and the relative positions of the revolving heart cam-wheel _c_, being also gradually changed, the upper or working needles are at length allowed to be drawn completely through the wool, for the purpose of combing out straight the whole length of its fibre.

In order to give to the machine the necessary movements, a train of toothed wheels and pinions is mounted, mostly on studs attached to the side of the frame; which train of wheels and pinions is shown by dots in the figure, to avoid confusion. The driving power, a horse or steam-engine, is communicated by a band to a rigger on the short axle _i_; which axle carries a pinion, taking into one of the wheels of the train. From this wheel the crank _e_, that works the lever _d_, is driven; and also, by geer from the same pinion, the axle of the wheel _b_, carrying the eccentric or heart-wheel cam, is also actuated, but slower than the crank-axle.

At the end of the axle of the wheel _b_, and cam _c_, a bevel pinion is affixed, which geers into a corresponding bevel pinion on the end of the lateral shaft _k_. The reverse end of this shaft has a worm or endless screw _l_, taking into a toothed wheel _m_; and this last-mentioned toothed wheel geers into a rack at the under part of the frame _g_.

It will hence be perceived, that by the movements of the train of wheels, a slow motion is given to the frame _g_, by which the lower needles carrying the wool are progressively advanced as the operation goes on; and also, that by the other wheels of the train, the heart-wheel cam is made to rotate, for the purpose of giving such varying directions to the stroke of the lever which slides upon its periphery, and to the working comb, as shall cause the comb to operate gradually upon the wool as it is brought forward. The construction of the frames which hold the needles, and the manner of fixing them in the machine, present no features of importance; it is therefore unnecessary to describe them farther, than to say, that the heckles are to be heated when used for combing wool. Instead of introducing the wool to be combed into the lower needles by hand, it is sometimes fed in, by means of an endless feeding-cloth, as shown in _fig._ 1206. This endless cloth is distended over two rollers, which are made to revolve, for the purpose of carrying the cloth with the wool forward, by means of the endless screw and pinions.

A slight variation in the machine is shown at _fig._ 1207., for the purpose of combing wool of long fibre, which differs from the former only in placing the combs or needle points upon a revolving cylinder or shaft. At the end of the axle of this shaft, there is a toothed wheel, which is actuated by an endless screw upon a lateral shaft. The axle of the cylinder on which the needles are fixed, is mounted in a movable frame or carriage, in order that the points of the needles may, in the first instance, be brought to act upon the ends of the wool only, and ultimately be so advanced as to enable the whole length of the fibres to be drawn through. The progressive advancement of this carriage, with the needle cylinder, is effected by the agency of the endless screw on the lateral shaft before mentioned.

Some combing-machines reduce the wool into a continuous sliver, which is ready for the drawing-frame; but the short slivers produced by the hand combing, must be first joined together, by what is called _planking_. These slivers are rolled up by the combers ten or twelve together, in balls called tops, each of which weighs half a pound. At the spinning-mill these are unrolled, and the slivers are laid on a long plank or trough, with the ends lapping over, in order to splice the long end of one sliver into the short end of another. The long end is that which was drawn off first from the comb, and contains the longer fibres; the short is that which comes last from the comb, and contains the shorter. The wool-comber lays all the slivers of each ball the same way, and marks the long end of each by twisting up the end of the sliver. It is a curious circumstance, that when a top or ball of slivers is unrolled and stretched out straight, they will not separate from each other without tearing and breaking, if the separation is begun at the short ends; but if they are first parted at the long ends, they will readily separate.

The machine for combing long wool, for which Messrs. Donisthorpe and Rawson obtained a patent in April, 1835, has been found to work well, and therefore merits a detailed description:--

_Fig._ 1208. is an elevation; _fig._ 1209. an end view; and _fig._ 1210. a plan; in which _a_, _a_, is the framing; _b_, the main shaft, bearing a pinion which drives the wheel and shaft _c_, in geer with the wheel _d_, on the shaft _e_. Upon each of the wheels _c_ and _d_, there are two projections or studs _f_, which cause the action of the combs _g_, _g_, of which _h_, _h_, are the tables or carriages. These are capable of sliding along the upper guide rails of the framing _a_. Through these carriages or tables _h_, _h_, there are openings or slits, shown by dotted lines, which act as guides to the holders _i_, _i_, of the combs _g_, _g_, rendering the holders susceptible of motion at right angles to the course pursued by the tables _h_. The combs are retained in the holders _i_, _i_, by means of the lever handles _j_, _j_, which move upon inclined surfaces, and are made to press on the surface of the heads of the combs _g_, _g_, so as to be retained in their places; and they are also held by studs affixed to the holders, which pass into the comb-heads. From the under side of the tables, forked projections _i_, _i_, stand out, which pass through the openings or slits formed in the tables _h h_; these projections are worked from side to side by the frame _k_, _k_, which turning on the axis or shaft _l_, _l_, is caused to vibrate, or rock to and fro, by the arms _m_, moved by the eccentric groove _n_, made fast to the shaft _e_. The tables _h_, are drawn inwards, by weights suspended on cords or straps _o_, _o_, which pass over friction pulleys _p_, _p_; whereby the weights have a constant tendency to draw the combs into the centre of the machine, as soon as it is released by the studs _f_, passing beyond the projecting arms _g_, on the tables. On the shaft _c_, a driving-tooth or catch _r_, is fixed, which takes into the ratchet wheel _s_, and propels one of its teeth at every revolution of the shaft _c_. This ratchet wheel turns on an axis at _t_; to the ratchet the pulley _v_ is made fast, to which the cord or band _w_ is secured, as also to the pulley _x_, on the shaft _y_. On the shaft _y_, there are two other pulleys _z_, _z_, having the cords or bands A, A, made fast to them, and also to the end of the gauge-plates B, furnished with graduated steps, against which the tables _h_, _h_, are drawing at each operation of the machine. In proportion as these gauge-plates are raised, the nearer the carriages or tables _h_, will be able to advance to the centre of the machine, and thus permit the combs _g_, _g_, to lay hold of, and comb, additional lengths of the woolly fibres. The gauge-plates B, are guided up by the bars C, which pass through openings, slots, or guides, made in the framing _a_, as shown by D.

To the ratchet wheel _s_, an inclined projection E, is made fast, which in the course of the rotation of the ratchet wheel, comes under the lever F, fixed to the shaft G, that turns in bearings H. To this shaft the levers I and J, are also fixed; I serving to throw out the click or catch K, from the ratchet wheel, by which the parts of the machine will be released, and restored to positions ready for starting again. The lever J, serves to slide the drum upon the driving shaft _b_, out of geer, by means of the forked handle L, when the machine is to be stopped, whenever it has finished combing a certain quantity of wool. The combs which hold the wool have a motion upwards, in order to take the wool out of the way of the combs _g_, _g_, as these are drawn into the centre of the machine; while the holding combs descend to lay the wool among the points of the combs _g_, _g_. For obtaining this upward and downward motion, the combs M, M, are placed upon the frame N, and retained there just as the combs _g_, _g_, are upon the holders _i_, _i_. The framing N is made fast to the bar or spindle O, which moves vertically through openings in the cross-head P, and the cross-framing of the machine Q; from the top of which, there is a strap passes over pulleys with a weight suspended to it; the cross-head being supported by the two guide-rods R, fixed to the cross-framing Q. It is by the guide-rods R, and the spindle O, that the frame N is made to move up and down; while the spindle is made to rise by the studs _f_, as the wheels _c_ and _d_ come successively under the studs _s_, on the spindle O.

A quantity of wool is to be placed on each of the combs _g_, _g_, and M, M, the machine being in the position shown in _fig._ 1210. When the main shaft _b_, is set in motion, it will drive by its pinion the toothed wheel _c_, and therefrom the remaining parts of the machine. The first effect of the movement will be to raise the combs M, M, sufficiently high to remove the wool out of the way of the combs _g_, _g_, which will be drawn towards the centre of the machine, as soon as they are released by the studs _f_, passing the projecting arms _q_, on the tables _h_; but the distance between the combs _g_, _g_, and the combs H, H, will depend on the height to which the gauge-plates B, have been raised. These plates are raised one step at each revolution of the shaft _c_; the combs _g_, _g_, will therefore be continually approaching more nearly to the combs M, M, till the plates B, are so much raised as to permit the tables _h_, to approach the plates B, below the lowest step or graduation, when the machine will continue to work. Notwithstanding the plates B, continuing to rise, there being only parallel surfaces against which the tables come, the combs _g_, _g_, will successively come to the same position, till the inclined projection E, on the ratchet wheel _s_, comes under the lever F, which will stop the machine. The wool which has been combed, is then to be removed, and a fresh quantity introduced. It should be remarked, that the combs _g_, _g_, are continually moving from side to side of the machine, at the same time that they are combing out the wool. The chief object of the invention is obviously to give the above peculiar motions to the combs _g_, _g_, and M, M; which may be applied also to combing goat-hair.

For the purposes of the worsted manufacture, wool should be rendered inelastic to a considerable degree, so that its fibres may form long lines, capable of being twisted into straight level yarn. Mr. Bayliffe, of Kendal, has sought to accomplish this object, first, by introducing into the _drawing_ machine a rapidly revolving wheel, in contact with the front drawing roller, by whose friction the filaments are heated, and at the same time deprived of their curling elasticity; secondly, by employing a movable regulating roller, by which the extent of surface on the periphery of the wheel that the lengths of wool is to act upon, may be increased or diminished at pleasure, and, consequently, the effect regulated or tempered as the quality of the wool may require; thirdly, the employment of steam in a rotatory drum, or hollow wheel, in place of the wheel first described, for the purpose of heating the wool, in the process of drawing, in order to facilitate the operation of straightening the fibres.

These objects may be effected in several ways; that is, the machinery may be variously constructed, and still embrace the principles proposed. _Fig._ 1211. shows one mode:--_a_, is the friction wheel; _b_, the front drawing roller, placed in the drawing frame in the same way as usual; the larger wheel _a_, constituting the lower roller of the pair of front drawing rollers; _c_, and _d_, are the pair of back drawing rollers, which are actuated by geer connected to the front rollers, as in the ordinary construction of drawing machines, the front rollers moving very considerably faster than the back rollers, and, consequently, drawing or extending the fibres of the sliver of wool, as it passes through between them; _e_, is a guide roller, bearing upon the periphery of the large wheel; _f_, is a tension roller, which presses the fibres of the wool down upon the wheel _a_.

Now, supposing the back rollers _c_ and _d_ to be turned with a given velocity, and the front roller _b_ to be driven much faster, the effect would be, that the fibres of wool constituting the sliver, passing through the machine, would be considerably extended between _b_ and _d_, which is precisely the effect accomplished in the ordinary drawing frame; but the wheel _a_, introduced into the machine in place of the lower front drawing roller, being made to revolve much faster than _b_, the sliver of wool extended over the upper part of its periphery from _b_, to the tension roller _f_, will be subjected to very considerable friction from the contact; and, consequently, the natural curl of the wool will be taken out, and its elasticity destroyed, which will enable the wool to proceed in a connected roving down to the spindle or flyer _h_, where it becomes twisted or spun into a worsted thread.

In order to increase or diminish the extent to which the fibres of wool are spread over the periphery of the wheel _a_, a regulating roller is adapted to the machine, as shown at _g_, in place of the tension roller _f_. This regulating roller _g_, is mounted by its pivots in bearings on the circular arms _h_, shown by dots. These circular arms turn loosely upon the axle of the wheel _a_, and are raised or depressed by a rack and a winch, not shown in the figure; the rack taking into teeth on the periphery of the circular arms. It will hence be perceived, that by raising the circular arms, the roller _g_, will be carried backward, and the fibres of wool pressed upon the periphery of the wheel to a greater extent. On the contrary, the depression of the circular arms will draw the roller _g_, forward, and cause the wool to be acted upon by a smaller portion of the periphery of the wheel _a_, and consequently subject it to less friction.

When it is desired to employ steam for the purpose of heating the wool, the wheel _a_, is formed as a hollow drum, and steam from a boiler, in any convenient situation, is conveyed through the hollow axle to the interior of the drum, which, becoming heated by that means, communicates heat also to the wool, and thereby destroys its curl and elasticity.

_Breaking-frame._--Here the slivers are _planked_, or spliced together, the long end of one to the short end of another; after which they are drawn out and extended by the rollers of the breaking-frame. A sketch of this machine is given in _fig._ 1212. It consists of four pairs of rollers A, B, C, D. The first pair A, receives the wool from the inclined trough E, which is the planking-table. The slivers are unrolled, parted, and hung loosely over a pin, in reach of the attendant, who takes a sliver, and lays it flat in the trough, and the end is presented to the rollers A, which being in motion, will draw the wool in; the sliver is then conducted through the other rollers, as shown in the figure: when the sliver has passed half through, the end of another sliver is placed upon the middle of the first, and they pass through together; when this second is passed half through, the end of a third is applied upon the middle of it, and in this way the short slivers produced by the combing are joined into one regular and even sliver.

The lower roller C receives its motion from the mill, by means of a pulley upon the end of its axis, and an endless strap. The roller which is immediately over it, is borne down by a heavy weight, suspended from hooks, which are over the pivots of the upper roller. The fourth pair of rollers D, moves with the same velocity as C, being turned by means of a small wheel upon the end of the axis of the roller C, which turns a wheel of the same size upon the axis of the roller D, by means of an intermediate wheel _d_, which makes both rollers turn the same way round. The first and second pairs of rollers, A and B, move only one-third as quick as C and D, in order to draw out the sliver between B and C to three times the length it was when put on the planking-table. The slow motion of the rollers A, is given by a large wheel _a_, fixed upon the axis of the roller A, and turned by the intermediate cog-wheels _b_, _c_, and _d_; the latter communicates between the rollers C and D. The pinions on the rollers C and D being only one-third the size of the wheel _a_, C and D turn three times as fast as A, for _b_, _c_, and _d_, are only intermediate wheels. The rollers B turn at the same rate as A. The upper roller C is loaded with a heavy weight, similar to the rollers A; but the other rollers, B and D, are no further loaded than the weight of the rollers.

The two pairs of rollers A, B, and C, D, are mounted in separate frames; and that frame which contains the third and fourth pairs C, D, slides upon the cast-iron frame F, which supports the machine, in order to increase or diminish the distance between the rollers B and C. There is a screw _f_, by which the frame of the rollers is moved, so as to adjust the machine according to the length of the fibres of the wool. The space between B and C should be rather more than the length of the fibres of the wool. The intermediate wheels _b_ and _c_, are supported upon pieces of iron, which are movable on centres; the centre for the piece which supports the wheel _b_ is concentric with the axis of the roller A; and the supporting piece for the wheel _c_ is fitted on the centre of the wheel _d_. By moving these pieces the intermediate wheels _b_ and _c_ can be always kept in contact, although the distance between the rollers is varied at times. By means of this breaking-frame, the perpetual sliver, which is made up by planking the sliver together, is equalized, and drawn out three times in length, and delivered into the can G.

_Drawing-frame._--Three of these cans are removed to the drawing-frame, which is similar to the breaking-frame, except that there is no planking-table E. There are five sets of rollers, all fixed upon one common frame F, the breaking-frame, which we have described, being the first. As fast as the sliver comes through one set of rollers, it is received into a can, and then three of these cans are put together, and passed again through another set of rollers. In the whole, the wool must pass through the breaker and four drawing-frames before the roving is begun. The draught being usually four times at each operation of drawing, and three times in the breaking, the whole will be 3 + 4 + 4 + 4 + 4 = 768; but to suit different sorts of wool, the three last drawing-frames are capable of making a greater draught, even to five times, by changing the pinions; accordingly the draught will be 3 + 4 + 5 + 5 + 5 = 1500 times.

The size of the sliver is diminished by these repeated drawings, because only three slivers are put together, and they are drawn out four times; so that, in the whole, the sliver is reduced to a fourth or a ninth of its original bulk.

The breaking-frame and drawing-frame which are used when the slivers are prepared by the combing-machines, are differently constructed; they have no planking-table, but receive three of the perpetual slivers of the combing-machine from as many tin cans, and draw them out from ten to twelve times. In this case, all the four rollers contribute to the operation of drawing: thus the second rollers B, move 2-1/2 times as fast as the rollers A; the third rollers C, move 8 times as fast as A; and the fourth rollers E, move 10-1/2 times as fast as A. In this case, the motion is given to the different rollers by means of bevelled wheels, and a horizontal axis, which extends across the ends of all the four rollers, to communicate motion from one pair of rollers to another.

There are three of these systems of rollers, which are all mounted on the same frame; and the first one through which the wool passes, is called the breaking-frame; but it does not differ from the others, which are called drawing-frames. The slivers which have passed through one system of rollers, are collected four or five together, and put through the drawing-rollers. In all, the slivers pass through three drawings, and the whole extension is seldom less than 1000 times, and for some kinds of wool much greater.

After the drawing of the slivers is finished, a pound weight is taken, and is measured by means of a cylinder, in order to ascertain if the drawing has been properly conducted; if the sliver does not prove of the length proposed, according to the size of worsted which is intended to be spun, the pinions of some of the drawing-frames are changed, to make the draught more or less, until it is found by experiment that one pound of the sliver measures the required length.

_Roving-frame._--This is provided with rollers, the same as the drawing-frames: it takes in one or two slivers together, and draws them out four times. By this extension, the sliver becomes so small, that it would break with the slightest force, and it is therefore necessary to give some twist; this is done by a spindle and flyer. See _Roving_, under COTTON MANUFACTURE.

_Spinning-frame._--This is so much like the roving-frame, that a short description will be sufficient. The spindles are more delicate, and there are three pairs of rollers, instead of two; the bobbins, which are taken off from the spindles of the roving-frame, when they are quite full, are stuck upon skewers, and the roving which proceeds from them is conducted between the rollers. The back pair turns round slowly; the middle pair turns about twice for once of the back rollers; and the front pair makes from twelve to seventeen turns for one turn of the back roller, according to the degree of extension which is required.

The spindles must revolve very quickly in the spinning-frame, in order to give the requisite degree of twist to the worsted. The hardest twisted worsted is called tammy warp; and when the size of this worsted is such as to be 20 or 24 hanks to the pound weight, the twist is about 10 turns in each inch of length. The least twist is given to the worsted for fine hosiery, which is from 18 to 24 hanks to the pound. The twist is from 5 to 6 turns per inch. The degree of twist is regulated by the size of the whirls or pulleys upon the spindle, and by the wheel-work which communicates the motion to the front rollers from the band-wheel, which turns the spindles.

It is needless to enter more minutely into the description of the spinning machinery, because the fluted roller construction, invented by Sir Richard Arkwright, fully described under COTTON MANUFACTURE, is equally applicable to worsted. The difference between the two, is chiefly in the distance between the rollers, which, in the worsted-frame, is capable of being increased or diminished at pleasure, according to the length of the fibres of the wool; and the draught or extension of the roving is far greater than in the cotton.

_Reeling._--The bobbins of the spinning-frame are placed in a row upon wires before a long horizontal reel, and the threads from 20 bobbins are wound off together. The reel is exactly a yard in circumference, and when it has wound off 80 turns, it rings a bell; the motion of the reel is then stopped, and a thread is passed round the 80 turns or folds which each thread has made. The reeling is then continued till another 80 yards is wound off, which is also separated by interweaving the same thread; each of these separate parcels is called a ley, and when 7 such leys are reeled, it is called a hank, which contains 560 yards. When this quantity is reeled off, the ends of the binding thread are tied together, to bind each hank fast, and one of the rails of the reel is struck to loosen the hanks, and they are drawn off at the end of the reel. These hanks are next hung upon a hook, and twisted up hard by a stick; then doubled, and the two parts twisted together to make a firm bundle. In this state, the hanks are weighed by a small index-machine, which denotes what number of the hanks will weigh a pound, and they are sorted accordingly into different parcels. It is by this means that the number of the worsted is ascertained as the denomination for its fineness: thus No. 24. means, that 24 hanks, each containing 560 yards, will weigh a pound, and so on.

This denomination is different from that used for cotton, because the hank of cotton contains 840 yards, instead of 560; but in some places the worsted hank is made of the same length as the cotton.

To pack up the worsted for market, the proper number of hanks is collected to make a pound, according to the number which has been ascertained; these are weighed as a proof of the correctness of the sorting, then tied up in bundles of one pound each, and four of these bundles are again tied together. Then 60 such bundles are packed up in a sheet, making a bale of 240 pounds, ready for market.

_Of the treatment of short wool for the cloth manufacture._--Short wool resembles cotton, not a little in the structure of its filaments, and is cleaned by the _willy_, as cotton is by the _willow_, which opens up the matted fleece of the wool-stapler, and cleans it from accidental impurities. Sheep’s wool for working into coarse goods, must be passed repeatedly through this machine, both before and after it is dyed; the second last time for the purpose of blending the different sorts together, and the last for imbuing the fibres intimately with oil. The oiled wool is next subjected to a first carding operation called _scribbling_, whereby it is converted into a broad thin fleece or lap, as cotton is by the breaker-cards of a cotton mill. The woollen lap is then worked by the cards proper, which deliver it in a narrow band or sliver. By this process the wool expands greatly in all its dimensions; while the broken or short filaments get entangled by crossing in every possible direction, which prepares them for the fulling operation. See _Carding_, under COTTON MANUFACTURE.

The _slubbing machine_, or _billy_, reduces the separate rolls of _cardings_ into a continuous slightly twisted spongy cord, which is sometimes called a roving. _Fig._ 1213. is a perspective representation of the slubbing machine in most common use. A, A, is the wooden frame; within which is the movable carriage D, D, which runs upon the lower side rails at _a_, _a_, on friction wheels at 1, 2, to make it move easily backwards and forwards from one end of the frame to the other. The carriage contains a series of steel spindles, marked 3, 3, which receive rapid rotation from a long tin drum F, by means of a series of cords passing round the pulley or whorl of each spindle. This drum, 6 inches in diameter, is covered with paper, and extends across the whole breadth of the carriage. The spindles are set nearly upright in a frame, and about 4 inches apart; their under ends being pointed conically, turn in brass sockets called steps, and are retained in their position by a small brass collet, which embraces each spindle at about the middle of its length. The upper half of each spindle projects above the top of the frame. The drum revolves horizontally before the spindles, having its axis a little below the line of the whorls; and receives motion, by a pulley at one of its ends, from an endless band which passes round a wheel E, like the large domestic wheel formerly used in spinning wool by hand, and of similar dimensions. This wheel is placed upon the outside of the main frame of the machine, and has its shafts supported by upright standards upon the carriage D. It is turned by the spinner placed at Q, with his right hand applied to a winch R, which gives motion to the drum, and thereby causes the spindles to revolve with great velocity.

Each spindle receives a soft cylinder or carding of wool, which comes through beneath a wooden roller C, C, at the one end of the frame. This is the _billy roller_, so much talked of in the controversies between the operatives and masters in the cotton factories, as an instrument of cruel punishment to children, though no such machine has been used in cotton mills for half a century at least. These woollen rolls proceed to the series of spindles, standing in the carriage, in nearly a horizontal plane. By the alternate advance and retreat of the carriage upon its railway, the spindles are made to approach to, and recede from, the roller C, with the effect of drawing out a given length of the soft cord, with any desired degree of twist, in the following manner:--

The carding rolls are laid down straight, side by side, upon the endless cloth, strained in an inclined direction between two rollers, one of which is seen at B, and the other lies behind C. One carding is allotted to a spindle; the total number of each in one machine being from 50 to 100. The roller C, of light wood, presses gently with its weight upon the cardings, while they move onwards over the endless cloth, with the running out of the spindle carriage. Immediately in front of the said roller, there is a horizontal wooden rail or bar G, with another beneath it, placed across the frame. The carding is conducted through between these two bars, the movable upper one being raised to let any aliquot portion of the roll pass freely. When this bar is again let down, it pinches the spongy carding fast; whence this mechanism is called the clasp. It is in fact the _clove_, originally used by Hargreaves in his cotton-jenny. The movable upper rail G, is guided between sliders, and a wire 7, descends from it to a lever C. When the spindle carriage D, D, is wheeled close home to the billy roller, a wheel 5, lifts the end 6 of the lever, which, by the wire 7, raises the upper bar or rail G, so as to open the clasp, and release all the card rolls. Should the carriage be now drawn a little way from the clasp bars, it would tend to pull a corresponding length of the cardings forward from the inclined plane B, C. There is a small catch, which lays hold of the upper bar of the clasp G, and hinders it from falling till the carriage has receded to a certain distance, and has thereby allowed from 7 to 8 inches of the cardings to be taken out. A stop upon the carriage then comes against the catch, and withdraws it; thus allowing the upper rail to fall and pinch the carding, while the carriage, continuing to recede, draws out or stretches that portion of the roll which is between the clasp and the spindle points. But during this time the wheel has been turned to keep the spindles revolving, communicating the proper degree of twist to the cardings in proportion to their extension, so as to prevent them from breaking.

It might be imagined that the slubbing cords would be apt to coil round the spindles; but as they proceed in a somewhat inclined direction to the clasp, they receive merely a twisting motion, continually slipping over the points of the spindles, without getting wound upon them. Whenever the operative or slubber has given a due degree of twist to the rovings, he sets about winding them upon the spindles into a conical shape, for which purpose he presses down the faller-wire 8, with his left hand, so as to bear it down from the points of the spindles, and place it opposite to their middle part. He next makes the spindles revolve, while he pushes in the carriage slowly, so as to coil the slubbing upon the spindle into a conical cop. The wire 8, regulates the winding-on of the whole series of slubbings at once, and receives its proper angle of depression for this purpose from the horizontal rail 4, which turns upon pivots in its ends, in brasses fixed on the standards, which rise from the carriage D. By turning this rail on its pivots, the wire 8 may be raised or lowered in any degree. The slubber seizes the rail 4 in his left hand, to draw the carriage out; but in returning it, he depresses the faller-wire, at the same time that he pushes the carriage before him.

The cardings are so exceedingly tender, that they would readily draw out, or even break, if they were dragged with friction upon the endless cloth of the inclined plane. To save this injurious traction, a contrivance is introduced for moving the apron. A cord is applied round the groove in the middle part of the upper roller, and after passing over pulleys, as shown in the figure, it has a heavy weight hung at the one end, and a light weight at the other, to keep it constantly extended, while the heavy weight tends to turn the rollers with their endless cloth round in such a direction as to bring forward the rovings, without putting any strain upon them. Every time that the carriage is pushed home, the larger weight gets wound up; and when the carriage is drawn out, the greater weight turns the roller, and advances the endless apron, so as to deliver the carding at the same rate as the carriage runs out; but when the proper quantity is delivered, a knot in the rope arrives at a fixed stop, which does not permit it to move any further; while at the same instant the roller 5 quits the lever 6, and allows the upper rail G, of the clasp to fall, and pinch the carding fast; the wheel E, being then set in motion, makes the spindles revolve; and the carriage being simultaneously drawn out, extends the slubbings while under the influence of twisting. In winding up the slubbings, the operative must take care to push in the carriage, and to turn the wheel round at such rates that the spindles will not take up faster than the carriage moves on its railway, or he would injure the slubbings. The machine requires the attendance of a child, to bring the cardings from the card-engine, to place them upon the sloping feed-cloth, and to join the ends of the fresh ones carefully to the ends of the others newly drawn under the roller. Slubbings intended for warp-yarn must be more twisted than those for weft; but each must receive a degree of torsion relative to the quality of the wool and of the cloth intended to be made. In general, however, no more twist should be given to the slubbings than is indispensable for enabling them to be drawn out to the requisite slenderness without breaking. This twist forms no part of the twist of the finished yarn, for the slubbing will be twisted in the contrary direction, when spun afterwards in the jenny or mule.

I may here remark, that various machines have been constructed of late years for making continuous card-ends, and slubbings, in imitation of the carding and roving of the COTTON MANUFACTURE; to which article I therefore refer my readers. The wool slubbings are now spun into yarn, in many factories, by means of the mule. Indeed, I have seen in France the finest yarn, for the _mousseline-de-laine_ fabrics, beautifully spun upon the self-actor mule of Sharp and Roberts.[72]

[72] See this admirable machine fully described and delineated in my _Cotton Manufacture of Great Britain_, vol. ii.

_Tentering._--When the cloth is returned from the fulling-mill (which see), it is stretched upon the tenter-frame, and left in the open air till dry.

In the woollen manufacture, as the cloth suffers, by the operation of the fulling-mill, a shrinkage of its breadth to well nigh one-half, it must at first be woven of nearly double its intended width when finished. Superfine six-quarter broad cloths must therefore be turned out of the loom twelve-quarters wide.

_Burling_ is the name of a process, in which the dried cloth is examined minutely in every part, freed from knots or uneven threads, and repaired by sewing any little rents, or inserting sound yarns in the place of defective ones.

_Teasling._--The object of this operation is to raise up the loose filaments of the woollen yarn into a nap upon one of the surfaces of the cloth, by scratching it either with thistle-heads, called teasels, or with teasling-cards or brushes, made of wire. The natural teasels are the balls which contain the seeds of the plant called _Dipsacus fullorum_; the scales which form the balls, project on all sides, and end in sharp elastic points, that turn downwards like hooks. In teasling by hand, a number of these balls are put into a small wooden frame, having crossed handles, eight or ten inches long; and when thus filled, form an implement not unlike a curry-comb, which is used by two men, who seize the teasel-frame by the handles, and scrub the face of the cloth, hung in a vertical position from two horizontal rails, made fast to the ceiling of the workshop. First, they wet the cloth, and work three times over, by strokes in the direction of the warp, and next of that of the weft, so as to raise all the loose fibres from the felt, and to prepare it for shearing. In large manufactories, this dressing operation is performed by a machine called a gig-mill, which originally consisted, and in most places still consists, of a cylinder bristled all over with the thistle-heads, and made to revolve rapidly while the cloth is drawn over it in a variety of directions. If the thistle be drawn in the line of the warp, the points act more efficaciously upon the weft, being perpendicular to its softer spun yarns. Inventors who have tried to give the points a circular or oblique action between the warp and the weft, proceed apparently upon a false principle, as if the cloth were like a plate of metal, whose substance could be pushed in any direction. Teasling really consists in drawing out one end of the filaments, and leaving the body of them entangled in the cloth; and it should seize and pull them perpendicularly to their length, because in this way it acts upon the ends, which being least implicated, may be most readily disengaged.

When the hooks of the thistles become clogged with flocks of wool, they must be taken out of the frame or cylinder, and cleaned by children with a small comb. Moisture, moreover, softens their points, and impairs their teasling powers; an effect which needs to be counterbalanced, by taking them out, and drying them from time to time. Many contrivances have, therefore, been proposed, in which metallic teasels of an unchangeable nature, mounted in rotatory machines, driven by power, have been substituted for the vegetable, which being required in prodigious quantities, become sometimes excessively scarce and dear in the clothing districts. In 1818, several schemes of that kind were patented in France, of which those of M. Arnold-Merick, and of MM. Taurin frères, of Elbœuf, are described in the 16th volume of _Brevets d’Invention expirés_. Mr. Daniell, cloth manufacturer in Wilts, renewed this invention under another form, by making his rotatory cards with two kinds of metallic wires, of unequal lengths; the one set, long, thin, and delicate, representing the points of the thistle; the other, shorter, stiffer, and blunter, being intended to stay the cloth, and to hinder the former from entering too far into it. But none of these processes have succeeded in discarding the natural teasel from the most eminent manufactories.

The French government purchased, in 1807, the patent of Douglas, an English mechanist, who had, in 1802, imported into France, the best system of gig-mills then used in the west of England. A working set of his machines having been placed in the _Conservatoire des Arts_, for public inspection, they were soon introduced into most of the French establishments, so as generally to supersede teasling (_lainage_) by hand. A description of them was published in the third volume of the _Brevets d’Invention_. The following is an outline of some subsequent improvements:--

1. As it was imagined that the seesaw action of the hand operative was in some respects more effectual than the uniform rotation of a gig-mill, this was attempted to be imitated by an alternating movement.

2. Others conceived that the seesaw motion was not essential, but that it was advantageous to make the teasels or cards act in a rectilinear direction, as in working by hand; this action was attempted by placing the two ends of the teasel-frame in grooves formed like the letter D, so that the teasel should act on the cloth only when it came into the rectilinear part. Mr. Wells, machine-maker, of Manchester, obtained a patent, in 1832, for this construction.

3. It was supposed that the teasels should not act perpendicularly to the weft, but obliquely or circularly upon the face of the cloth. Mr. Ferrabee, of Gloucester, patented, in 1830, a scheme of this kind, in which the teasels are mounted upon two endless chains, which traverse from the middle of the web to the selvage or list, one to the right, and another to the left hand, while the cloth itself passes under them with such a velocity, that the effect, or _resultant_, is a diagonal action, dividing into two equal parts the rectangle formed by the weft and warp yarns. Three patent machines of Mr. George Oldland--the first in 1830, the second and third in 1832--all proceed upon this principle. In the first, the teasels are mounted upon discs made to turn flat upon the surface of the cloth; in the second, the rotating discs are pressed by corkscrew spiral springs against the cloth, which is supported by an elastic cushion, also pressed against the discs by springs; and in the third machine, the revolving discs have a larger diameter, and they turn, not in a horizontal, but a vertical plane.

4. Others fancied that it would be beneficial to support the reverse side of the cloth by flat hard surfaces, while acting upon its face with cards or teasels. Mr. Joseph Cliseld Daniell, having stretched the cloth upon smooth level stones, teasels them by hand. 5. Messrs. Charlesworth and Mellor obtained a patent, in 1829, for supporting the back of the cloth with elastic surfaces, while the part was exposed to the teasling action. 6. Elasticity has also been imparted to the teasels, in the three patent inventions of Mr. Sevill, Mr. J. C. Daniell, and Mr. R. Atkinson. 7. It has been thought useful to separate the teasel-frames upon the drum of the gig-mill, by simple rollers, or by rollers heated with steam, in order to obtain the combined effect of calendering and teasling. Mr. J. C. Daniell, Mr. G. Haden, and Mr. J. Rayner, have obtained patents for contrivances of this kind. 8. Several French schemes have been mounted for making the gig-drum act upon the two sides of the cloth, or even to mount two drums on the same machine.

Mr. Jones, of Leeds, contrived a very excellent method of stretching the cloth, so as to prevent the formation of folds or wrinkles. (See Newton’s Journal, vol. viii., 2nd series, page 126.) Mr. Collier, of Paris, obtained a patent, in 1830, for a greatly improved gig-mill, upon Douglas’s plan, which is now much esteemed by the French clothiers. The following figures and description exhibit one of the latest and best teasling machines. It is the invention of M. Dubois and Co., of Louviers, and is now doing excellent work in that celebrated seat of the cloth manufacture.

In the fulling-mill, the woollen web acquires body and thickness, at the expense of its other dimensions; for being thereby reduced about one-third in length, and one-half in breadth, its surface is diminished to one-third of its size as it comes out of the loom; and it has, of course, increased threefold in thickness. As the filaments drawn forth by teasling, are of very unequal lengths, they must be shorn to make them level, and with different degrees of closeness, according to the quality of the stuff, and the appearance it is desired to have. But, in general, a single operation of each kind is insufficient; whence, after having passed the cloth once through the gig-mill, and once through the shearing-machine (_tondeuse_), it is ready to receive a second teasling, deeper than the first, and then to suffer a second shearing. Thus, by the alternate repetition of these processes, as often as is deemed proper, the cloth finally acquires its wished-for appearance. Both of these operations are very delicate, especially the first; and if they be ill conducted, the cloth is weakened, so as to tear or wear most readily. On the other hand, if they be skilfully executed, the fabric becomes not only more sightly, but it acquires strength and durability, because its face is changed into a species of fur, which protects it from friction and humidity.

_Figs._ 1214, 1215., represent the gig-mill in section, and in front elevation. A, B, C, D, A´, B´, C´, D´, being the strong frame of iron, cast in one piece, having its feet enlarged a little more to the inside than to the outside, and bolted to large blocks in the stone pavement. The two uprights are bound together below by two cross-beams A´´, being fastened with screw-bolts at the ears _a´´_, _a´´_; and at top, by the wrought-iron stretcher-rod D, whose ends are secured by screw-nuts at D, D´. The drum is mounted upon a wrought-iron shaft F, which bears at its right end (_fig._ 1215.), exterior to the frame, the usual riggers, or fast and loose pulley, _ff´´_, _f´_, which give motion to the machine by a band from the main shaft of the mill. On its right end, within the frame, the shaft F, has a bevel wheel F´, for transmitting movement to the cloth, as shall be afterwards explained. Three crown wheels G, of which one is shown in the section, _fig._ 1214., are, as usual, keyed by a wedge to the shaft F. Their contour is a sinuous band, with six semi-cylindrical hollows, separated alternately by as many portions of the periphery. One of these three wheels is placed in the middle of the shaft F, and the other two, towards its extremities. Their size may be judged of, from inspection of _fig._ 1214. After having set them so that all their spokes or radii correspond exactly, the 16 sides H, are made fast to the 16 portions of the periphery, which correspond in the three wheels. These sides are made of sheet iron, curved into a gutter form, _fig._ 1214., but rounded off at the end, _fig._ 1215., and each of them is fixed to the three felloes of the wheels by three bolts _h_. The elastic part of the plate iron allows of their being sufficiently well adjusted, so that their flat portions furthest from the centre may lie pretty truly on a cylindrical surface, whose axis would coincide with that of the shaft F.

Between the 16 sides there are 16 intervals, which correspond to the 16 hollowings of each of the wheels. Into these intervals are adjusted, with proper precautions, 16 frames bearing the teasels which are to act upon the cloth. These are fitted in as follows:--Each has the shape of a rectangle, of a length equal to that of the drum, but their breadth only large enough to contain two thistle-heads set end to end, thus making two rows of parallel teasels throughout the entire length, (see the contour in _fig._ 1214.) A portion of the frame is represented in _fig._ 1216. The large side I, against which the tops of the teasels rest, is hollowed out into a semi-cylinder, and its opposite side is cleft throughout its whole length, to receive the tails of the teasels, which are seated and compressed in it. There are, moreover, cross-bars _i_, which serve to maintain the sides of the frame I, at an invariable distance, and to form short compartments for keeping the thistles compact. The ends are fortified by stronger bars _k_, _k_, with projecting bolts to fasten the frames between the ribs. The distance of the sides of the frame I, I´, ought to be such, that if a frame be laid upon the drum, in the interval of two ribs, the side I will rest upon the inclined plane of one of the ribs, and the side I´ upon the inclined plane of the other, (see _fig._ 1214.); while at the same time the bars _k_, of the two ends of the frame, rest upon the flat parts of the ribs themselves. This point being secured, it is obvious, that if the ends of the bars _k_ be stopped, the frame will be made fast. But they need not be fixed in a permanent manner, because they must be frequently removed and replaced. They are fastened by the clamp, (_figs._ 1217, 1218.), which is shut at the one end, and furnished at the other with a spring, which can be opened or shut at pleasure. 2 and 4, in _fig._ 1215. (near the right end of the shaft F), shows the place of the clamp, _figs._ 1217, 1218. The bar of the right hand is first set in the clamp, by holding up its other end; the frame is then let down into the left-hand clamp.

The cloth is wound upon the lower beam Q, _fig._ 1214.; thence it passes in contact with a wooden cylinder T, turning upon an axis, and proceeds to the upper beam P, on to which it is wound: by a contrary movement, the cloth returns from the beam P to Q, over the cylinder T; and may thus go from the one to the other as many times as shall be requisite. In these successive circuits it is presented to the action of the teasels, under certain conditions. In order to be properly teasled, it must have an equal tension throughout its whole breadth during its traverse; it must be brought into more or less close contact with the drum, according to the nature of the cloth, and the stage of the operations; sometimes being a tangent to the surface, and sometimes embracing a greater or smaller portion of its contour, it must travel with a determinate speed, dependent upon the velocity of the drum, and calculated so as to produce the best result: the machine itself must make the stuff pass alternately from one winding beam to the other.

In _fig._ 1215., before the front end of the machine, there is a vertical shaft L, as high as the framework, which revolves with great facility, in the bottom step _l_, the middle collet _l´_, and top collet _l´´_, in the prolongation of the stretcher D. Upon this upright shaft are mounted--1. a bevel wheel L´; 2. an upper bevel pinion M, with its boss M´; 3. a lower bevel pinion N, with its boss N´. The bevel wheel L´ is keyed upon the shaft L, and communicates to it the movement of rotation which it receives from the pinion _f_, with which it is in geer; but the pinion _f_, which is mounted upon the shaft F of the drum, participates in the rotation which this shaft receives from the prime mover, by means of the fast rigger-pulley _f´_. The upper pinion M is independent upon the shaft L; that is to say, it may be slidden along it, up and down, without being driven by it; but it may be turned in an indirect manner by means of six curved teeth, projecting from its bottom, and which may be rendered active or not, at pleasure; these curved teeth, and their intervals, correspond to similar teeth and intervals upon the top of the boss M´, which is dependent, by feathered indentations, upon the rotation of L, though it can slide freely up and down upon it. When it is raised, therefore, it comes into geer with M. The pinion N, and its boss, have a similar mode of being thrown into and out of geer with each other. The bosses M´ and N´, ought always to be moved simultaneously, in order to throw one of them into geer, and the other out of geer. The shaft L serves to put the cloth in motion, by means of the bevel wheels P´´ and Q´´, upon the ends of the beams P, Q, which take into the pinions M and N.

The mechanism destined to stretch the cloth is placed at the other end of the machine, where the shafts of the beams P, Q, are prolonged beyond the frame, and bear at their extremities P´ and Q´, armed each with a brake. The beam P (_fig._ 1214.), turns in an opposite direction to the drum; consequently the cloth is wound upon P, and unwound from Q. If, at the same time as this is going on, the handle R´, of the brake-shaft, be turned so as to clasp the brake of the pulley Q´, and release that of the pulley P´, it is obvious that a greater or smaller resistance will be occasioned in the beam Q, and the cloth which pulls it in unwinding, will be able to make it turn only when it has acquired the requisite tension; hence it will be necessary, in order to increase or diminish the tension, to turn the handle R´ a little more or a little less in the direction which clasps the brake of the pulley Q´; and as the brake acts in a very equable manner, a very equable tension will take place all the time that the cloth takes to pass. Besides, should the diminution of the diameter of the beam Q, render the tension less efficacious in any considerable degree, the brake would need to be unclamped a very little, to restore the primitive tension.

When the cloth is to be returned from the beam P, to the beam Q, Z must be lowered, to put the shaft L out of geer above, and in geer below; then the cloth-beam Q, being driven by that vertical shaft, it will turn in the same direction as the drum, and will wind the cloth round its surface. In order that it may do so, with a suitable tension, the pulley Q´ must be left free, by clasping the brake of the pulley P´, so as to oppose an adequate resistance.

The cloth is brought into more or less close contact with the drum as follows:--There is for this purpose a wooden roller T, against which it presses in passing from the one winding beam to the other, and which may have its position changed relatively to the drum. It is obvious, for example, that in departing from the position represented in _fig._ 1214., where the cloth is nearly a tangent to the drum, if the roller T´ be raised, the cloth will cease to touch it; and if it be lowered, the cloth will, on the contrary, embrace the drum over a greater or less portion of its periphery. For it to produce these effects, the roller is borne at each end, by iron gudgeons, upon the heads of an arched rack T´´ (_fig._ 1214.), where it is held merely by pins. These racks have the same curvature as the circle of the frame, against which they are adjusted by two bolts; and by means of slits, which these bolts traverse, they may be slidden upwards or downwards, and consequently raise or depress the roller T. But to graduate the movements, and to render them equal in the two racks, there is a shaft U, supported by the uprights of the frame, and which carries, at each end, pinions U´, U´´, which work into the two racks T´, T´´: this shaft is extended in front of the frame, upon the side of the head of the machine (_fig._ 1215.), and there it carries a ratchet wheel _u_, and a handle _u´_. The workman, therefore, requires merely to lay hold of the handle, and turn it in the direction of the ratchet wheel, to raise the racks, and the roller T, which they carry; or to lift the click or catch, and turn the handle in the opposite direction, when he wishes to lower the roller, so as to apply the cloth to a larger portion of the drum.

CLOTH CROPPING.

Of machines for cropping or shearing woollen cloths, those of Lewis and Davis have been very generally used.

_Fig._ 1219. is an end view, and _fig._ 1220. is a side view, of Lewis’s machine, for shearing cloth from list to list. _Fig._ 1221. is an end view of the carriage, with the rotatory cutter detached from the frame of the machine, and upon a larger scale: _a_, is a cylinder of metal, on which is fixed a triangular steel wire; this wire is previously bent round the cylinder in the form of a screw, as represented at _a_, _a_, in _fig._ 1219., and, being hardened, is intended to constitute one edge of the shear or cutter.

The axis of the cylindrical cutter _a_, turns in the frame _b_, which, having proper adjustments, is mounted upon pivots _c_, in the standard of the travelling carriage _d_, _d_; and _e_, is the fixed or ledger blade, attached to a bar _f_, which constitutes the other edge of the cutter; that is, the stationary blade, against which the edges of the rotatory cutter act; _f_ and _g_, are flat springs, intended to keep the cloth (shown by dots) up against the cutting edges. The form of these flat springs _f_, _g_, is shown at _figs._ 1222. and 1223., as consisting of plates of thin metal cut into narrow slips (_fig._ 1222.), or perforated with long holes, (_fig._ 1223.) Their object is to support the cloth, which is intended to pass between them, and operate as a spring bed, bearing the surface of the cloth against the cutters, so that its pile or nap may be cropped off or shorn as the carriage _d_ is drawn along the top rails of the standard or frame of the machine _h_, _h_, by means of cords.

The piece of cloth to be shorn, is wound upon the beam _k_, and its end is then conducted through the machine, between the flat springs _f_ and _g_ (as shown in _fig._ 1221.), to the other beam _l_, and is then made fast; the sides or lists of the cloth being held and stretched by small hooks, called habiting hooks. The cloth being thus placed in the machine, and drawn tight, is held distended by means of ratchets on the ends of the beams _k_ and _l_, and palls. In commencing the operation of shearing, the carriage _d_, must be brought back, as in _fig._ 1221., so that the cutters shall be close to the list; the frame of the cutters is raised up on its pivots as it recedes, in order to keep the cloth from injury, but is lowered again previously to being put in action. A band or winch is applied to the rigger or pulley _m_, which, by means of an endless cord passed round the pulley _n_, at the reverse end of the axle of _m_, and round the other pulleys _o_ and _p_, and the small pulley _q_, on the axle of the cylindrical cutter, gives the cylindrical cutter a very rapid rotatory motion; at the same time a worm, or endless screw, on the axle of _m_ and _n_, taking into the teeth of the large wheel _r_, causes that wheel to revolve, and a small drum _s_, upon its axle, to coil up the cord, by which the carriage _d_, with the cutters _a_ and _e_, and the spring bed _f_ and _g_, are slowly, but progressively, made to advance, and to carry the cutters over the face of the cloth, from list to list; the rapid rotation of the cutting cylinder _a_, producing the operation of cropping or shearing the pile.

Upon the cutting cylinder, between the spiral blades, it is proposed to place stripes of plush, to answer the purpose of brushes, to raise the nap or pile as the cylinder goes around, and thereby assist in bringing the points of the wool up to the cutters.

The same contrivance is adapted to a machine for shearing the cloth lengthwise.

_Fig._ 1224. is a geometrical elevation of one side of Mr. Davis’s machine. _Fig._ 1225. a plan or horizontal representation of the same, as seen in the top; and _fig._ 1226. a section taken vertically across the machine near the middle, for the purpose of displaying the working parts more perfectly than in the two preceding figures. These three figures represent a complete machine in working condition, the cutters being worked by a rotatory motion, and the cloth so placed in the carriage as to be cut from list to list. _a_, _a_, _a_, is a frame or standard, of wood or iron, firmly bolted together by cross braces at the ends and in the middle. In the upper side-rails of the standard, there is a series of axles carrying anti-friction wheels _b_, _b_, _b_, upon which the side-rails _c_, _c_, of the carriage or frame that bears the cloth runs, when it is passing under the cutters in the operation of shearing. The side-rails _c_, _c_, are straight bars of iron, formed with edges _v_, on their under sides, which run smoothly in the grooves of the rollers _b_, _b_, _b_. These side-rails are firmly held together by the end stretchers _d_, _d_. The sliding frame has attached to it the two lower rollers _e_, _e_, upon which the cloth intended to be shorn is wound; the two upper lateral rollers _f_, _f_, over which the cloth is conducted and held up; and the two end rollers _g_, _g_, by which the habiting rails _h_, _h_, are drawn tight.

In preparing to shear a piece of cloth, the whole length of the piece is, in the first place, tightly rolled upon one of the lower rollers _e_, which must be something longer than the breadth of the cloth from list to list. The end of the piece is then raised, and passed over the top of the lateral rollers _f_, _f_, whence it is carried down to the other roller _e_, and its end or farral is made fast to that roller. The hooks of the habiting rails _h_, _h_, are then put into the lists, and the two lower rollers _e_, _e_, with the two end rollers _g_, _g_, are then turned, for the purpose of drawing up the cloth, and straining it tight, which tension is preserved by ratchet wheels attached to the ends of the respective rollers, with palls dropping into their teeth. The frame carrying the cloth, is now slidden along upon the top standard rails by hand, so that the list shall be brought nearly up to the cutter _i_, _i_, ready to commence the shearing operation; the bed is then raised, which brings the cloth up against the edges of the shears.

The construction of the bed will be seen by reference to the cross section _fig._ 1226. It consists of an iron or other metal roller _k_, _k_, turned to a truly cylindrical figure, and covered with cloth or leather, to afford a small degree of elasticity. This roller is mounted upon pivots in a frame _l_, _l_, and is supported by a smaller roller _m_, similarly mounted, which roller _m_, is intended merely to prevent any bending or depression of the central part of the upper roller or bed _k_, _k_, so that the cloth may be kept in close contact with the whole length of the cutting blades.

In order to allow the bed _k_ to rise and fall, for the purpose of bringing the cloth up to the cutters to be shorn, or lowering it away from them after the operation, the frame _l_, _l_, is made to slide up and down in the grooved standard _n_, _n_, the movable part enclosed within the standard being shown by dots. This standard _n_, is situated about the middle of the machine, crossing it immediately under the cutters, and is made fast to the frame _a_, by bolts and screws. There is a lever _o_, attached to the lower cross-rail of the standard, which turns upon a fulcrum-pin, the extremity of the shorter arm of which lever acts under the centre of the sliding-frame, so that by the lever _o_, the sliding-frame, with the bed, may be raised or lowered, and when so raised, be held up by a spring catch _j_.

It being now explained by what means the bed which supports the cloth is constructed, and brought up, so as to keep the cloth in close contact with the cutters, while the operation of shearing is going on; it is necessary, in the next place, to describe the construction of the cutters, and their mode of working; for which purpose, in addition to what is shown in the first three figures, the cutters are also represented detached, and upon a larger scale, in _fig._ 1227.

In this figure is exhibited a portion of the cutters in the same situation as in _fig._ 1221.; and alongside of it is a section of the same, taken through it at right angles to the former; _p_, is a metallic bar or rib, somewhat of a wedge form, which is fastened to the top part of the standard _a_, _a_, seen best in _fig._ 1220. To this bar a straight blade of steel _g_, is attached by screws, the edge of which stands forward even with the centre or axis of the cylindrical cutter _i_, and forms the ledger blade, or lower fixed edge of the shears. This blade remains stationary, and is in close contact with the pile or nap of the cloth, when the bed _k_, is raised, in the manner above described.

The cutter or upper blade of the shears, is formed by inserting two or more strips of plate steel _r_, _r_, in twisted directions, into grooves in the metallic cylinder _i_, _i_, the edges of which blades _r_, as the cylinder _i_ revolves, traverse along the edge of the fixed or ledger blade _g_, and by their obliquity produce a cutting action like shears; the edges of the two blades taking hold of the pile or raised nap, as the cloth passes under it, shaves off the superfluous ends of the wool, and leaves the face smooth.

Rotatory motion is given to the cutting cylinder _i_, by means of a band leading from the wheel _s_, which passes round the pulley fixed on the end of the cylinder _i_, the wheel _s_ being driven by a band leading from the rotatory part of a steam-engine, or any other first mover, and passed round the rigger _t_, fixed on the axle _s_. Tension is given to this band by a tightening pulley _u_, mounted on an adjustable sliding-piece _v_, which is secured to the standard by a screw; and this rigger is thrown in and out of geer by a clutch-box and lever, which sets the machine going, or stops it.

In order to give a drawing stroke to the cutter, which will cause the piece of cloth to be shorn off with better effect, the upper cutter has a slight lateral action, produced by the axle of the cutting cylinder being made sufficiently long to allow of its sliding laterally about an inch in its bearings; which sliding is effected by a cam _w_, fixed at one end. This cam is formed by an oblique groove, cut round the axle, (see _w_, _fig._ 1227.) and a tooth _x_, fixed to the frame or standard which works in it, as the cylinder revolves. By means of this tooth, the cylinder is made to slide laterally, a distance equal to the obliquity of the groove _w_, which produces the drawing stroke of the upper shear. In order that the rotation of the shearing cylinder may not be obstructed by friction, the tooth _x_, is made of two pieces, set a little apart, so as to afford a small degree of elasticity.

The manner of passing the cloth progressively under the cutters is as follows:--On the axle of the wheel _s_, and immediately behind that wheel, there is a small rigger, from which a band passes to a wheel _y_, mounted in an axle turning in bearings on the lower side-rail of the standard _a_. At the reverse extremity of this axle, there is another small rigger 1, from which a band passes to a wheel 2, fixed on the axle 3, which crosses near the middle of the machine, seen in _fig._ 1226. Upon this axle there is a sliding pulley 4, round which a cord is passed several times, whose extremities are made fast to the ends of the sliding carriage _d_; when, therefore, this pulley is locked to the axle, which is done by a clutch box, the previously described movements of the machine cause the pulley 4 to revolve, and by means of the rope passed round it, to draw the frame, with the cloth, slowly and progressively along under the cutters.

It remains only to point out the contrivance whereby the machinery throws itself out of geer, and stops its operations, when the edge of the cloth or list arrives at the cutters.

At the end of one of the habiting rails _h_, there is a stop affixed by a nut and screw 5, which, by the advance of the carriage, is brought up and made to press against a lever 6; when an arm from this lever 6, acting under the catch 7, raises the catch up, and allows the hand-lever 8, which is pressed upon by a strong spring, to throw the clutch-box 10, out of geer with the wheel 8; whereby the evolution of the machine instantly ceases. The lower part of the lever 6, being connected by a joint to the top of the lever _j_, the receding of the lever 6, draws back the lower catch _j_, and allows the sliding frame _l_, _l_, within the bed _k_, to descend. By now turning the lower rollers _e_, _e_, another portion of the cloth is brought up to be shorn; and when it is properly habited and strained, by the means above described, the carriage is slidden back, and, the parts being all thrown into geer, the operation goes on as before.

Mr. Hirst’s improvements in manufacturing woollen cloths, for which a patent was obtained in February, 1830, apply to that part of the process where a permanent lustre is given usually by what is called roll-boiling; that is, stewing the cloth, when tightly wound upon a roller, in a vessel of hot water or steam. As there are many disadvantages attendant upon the operation of roll-boiling, such as injuring the cloths, by overheating them, which weakens the fibre of the wool, and also changes some colours, he substituted, in place of it, a particular mode of acting upon the cloths, by occasional or intermitted immersion in hot water, and also in cold water, which operations may be performed either with or without pressure upon the cloth, as circumstances may require.

The apparatus which he proposes to employ for carrying on his improved process, is shown in the accompanying drawing. _Fig._ 1228. is a front view of the apparatus, complete, and in working order; _fig._ 1229. is a section, taken transversely through the middle of the machine, in the direction of _fig._ 1230.; and _fig._ 1230. is an end view of the same; _a_, _a_, _a_, is a vessel or tank, made of iron or wood, or any other suitable material: sloping at the back and front, and perpendicular at the ends. This tank must be sufficiently large to admit of half the diameter of the cylinder or drum _b_, _b_, _b_, being immersed into it, which drum is about four feet diameter, and about six feet long, or something more than the width of the piece of cloth intended to be operated upon. This cylinder or drum _b_, _b_, is constructed by combining segments of wood cut radially on their edges, secured by screw-bolts to the rims of the iron wheels, having arms, with an axle passing through the middle.

The cylinder or drum being thus formed, rendered smooth on its periphery, and mounted upon its axle in the tank, the piece of cloth is wound upon it as tightly as possible, which is done by placing it in a heap upon a stool, as at _c_, _fig._ 1229., passing its end over and between the tension-rollers _d_, _e_, and then securing it to the drum, the cloth is progressively drawn from the heap, between the tension-rollers, which are confined by a pall and ratchet, on to the periphery of the drum, by causing the drum to revolve upon its axis, until the whole piece of cloth is tightly wound upon the drum; it is then bound round with canvas or other wrappers, to keep it secure.

If the tank has not been previously charged with clean and pure water, it is now filled to the brim, as shown at _fig._ 1229., and opening the stopcock of the pipe _f_, which leads from a boiler, the steam is allowed to blow through the pipe, and discharge itself at the lower end, by which means the temperature of the water is raised in the tank to about 170° Fahr. Before the temperature of the water has got up, the drum is set in slow rotatory motion, in order that the cloth may be uniformly heated throughout; the drum making about one rotation per minute. The cloth, by immersion in the hot water, and passing through the cold air, in succession, for the space of about eight hours, gets a smooth soft face, the texture not being rendered harsh, or otherwise injured, as is frequently the case by roll-boiling.

Uniform rotatory motion to the drum is shown in _fig._ 1228., in which _g_ is an endless screw or worm, placed horizontally, and driven by a steam-engine or any other first mover employed in the factory. This endless screw takes into the teeth of, and drives, the vertical wheel _h_, upon the axle of which the coupling-box _i_, _i_, is fixed, and, consequently, continually revolves with it. At the end of the shaft of the drum, a pair of sliding clutches _k_, _k_, are mounted, which, when projected forward, as shown by dots in _fig._ 1228., produce the coupling or locking of the drum-shaft to the driving wheel, by which the drum is put in motion; but on withdrawing the clutches _k_, _k_, from the coupling-box _i_, _i_, as in the figure, the drum immediately stands still.

After operating upon the cloth in the way described, by passing it through hot water for the space of time required, the hot water is to be withdrawn by a cock at the bottom, or otherwise, and cold water introduced into the tank in its stead; in which cold water the cloth is to be continued turning, in the manner above described, for the space of twenty-four hours, which will perfectly fix the lustre that the face of the cloth has acquired by its immersion in the hot water, and leave the pile or nap, to the touch, in a soft silky state.

In the cold-water operation he sometimes employs a heavy pressing roller _l_, which, being mounted in slots in the frame or standard, revolve with the large drum, rolling over the back of the cloth as it goes round. This roller may be made to act upon the cloth with any required pressure, by depressing the screws _m_, _m_, or by the employment of weighted levers, if that should be thought necessary.

_Pressing_ is the last finish of cloth to give it a smooth level surface. The piece is folded backwards and forwards in yard lengths, so as to form a thick package on the board of a screw or hydraulic press. Between every fold sheets of glazed paper are placed to prevent the contiguous surfaces of cloth from coming into contact; and at the end of every twenty yards, three hot iron plates are inserted between the folds, the plates being laid side by side, so as to occupy the whole surface of the folds. Thin sheets of iron not heated are also inserted above and below the hot plates to moderate the heat. When the packs of cloth are properly folded, and piled in sufficient number in the press, they are subjected to a severe compression, and left under its influence till the plates get cold. The cloth is now taken out and folded again, so that the creases of the former folds may come opposite to the flat faces of the paper, and be removed by a second pressure. In finishing superfine cloths, however, a very slight pressure is given with iron plates but moderately warmed. The satiny lustre and smoothness given by strong compression with much heat is objectionable, as it renders the surface apt to become spotted and disfigured by rain.

WOOTZ, is the Indian name of steel.

WORT, is the fermentable infusion of malt or grains. See BEER.

WOULFE’S APPARATUS, is a series of vessels, connected by tubes, for the purpose of condensing gaseous products in water. See ACETIC ACID, _fig._ 1.; also MURIATIC ACID.

X.

XANTHINE, is the name given by Kuhlmann to the yellow dyeing-matter contained in madder.

Y.

YEAST, is the froth of fermenting worts. See BEER and FERMENTATION.

YELLOW DYE. (_Teinture jaune_, Fr.; _Gelbfarben_, Germ.) _Annotto_, _dyer’s-broom_ (_Genista tinctoria_), _fustic_, _fustet_, _Persian or French berries_, _quercitron bark_, _saw-wort_ (_Serratula tinctoria_), _turmeric_, _weld_, and _willow leaves_, are the principal yellow dyes of the vegetable kingdom; _chromate of lead_, _iron-oxide_, _nitric acid_ (for silk), _sulphuret of antimony_, and _sulphuret of arsenic_, are those of the mineral kingdom. Under these articles, as also under CALICO-PRINTING, DYEING, and MORDANTS, ample instructions will be found for communicating this colour to textile and other fibrous substances. Alumina and oxide of tin are the most approved bases of the above vegetable dyes. A nankin dye may be given with _bablah_, especially to cotton oiled preparatory to the Turkey-red process. See MADDER.

YELLOW, KING’S, is a poisonous yellow pigment. See ARSENIC and ORPIMENT.

YTTRIA, is a rare earth, extracted from the minerals gadolinite and yttrotantalite, being an oxide of the metal yttrium.

Z.

ZAFFRE. See COBALT.

ZEDOARY, is the root of a plant which grows in Malabar, Ceylon, &c. It occurs in wrinkled pieces, externally ash-coloured, internally brownish-red; possessed of a fragrant odour, somewhat resembling camphor; and of a pungent, aromatic, bitterish taste. It contains, according to Bucholz, 1·42 of volatile oil, of a burning camphorated taste; 3·60 of a soft, bitter, aromatic resin; 11·75 of a bitter aromatic extract, mixed with a little resin and potash-salts; 4·5 of gum; 9 of vegetable mucilage; 3·60 of starch; 8·0 of a starchy extract from the woody fibre, by means of caustic potassa, along with 31·2 of another matter, 12·89 of woody fibre, and 15 of water. According to Morin, this root, contains besides, an azotized substance, analogous to the extract of beef.

ZIMOME, is a principle supposed by Taddei to exist in the gluten of wheat-flour. Its identity is not recognised by later chemists.

ZIRCON. See HYACINTH and LAPIDARY.

ZIRCONIA, is a rare earth, extracted from the minerals zircon and hyacinth; it is an oxide of zirconium, a substance possessing externally none of the metallic characters, but resembling rather charcoal powder, which burns briskly, and almost with explosive violence.

ZINC, is a metal of a bluish-white colour, of considerable lustre when broken across, but easily tarnished by the air; its fracture is hackly, and foliated with small facets, irregularly set. It has little cohesion, and breaks in thin plates before the hammer, unless it has been previously subjected to a regulated process of lamination, at the temperature of from 220° to 300° F., whereby it becomes malleable, and retains its malleability and ductility afterwards. On this singular property, a patent was taken out by Messrs. Hobson and Sylvester, of Sheffield, many years ago, for manufacturing sheet zinc, for covering the roofs of houses, and sheathing ships; but the low price of copper at that time, and its superior tenacity, rendered their patent ineffective. The specific gravity of zinc varies from 6·9 to 7·2, according to the condensation it has received. It melts under a red heat, at about the 680th or 700th degree of Fahrenheit’s scale. When exposed to this heat with contact of air, the metal takes fire, and burns with a brilliant bluish-white light, while a few flocculi, of a woolly-looking white matter, rise out of the crucible, and float in the air. The result of the combustion is a white powder, formerly called flowers, but now oxide of zinc; consisting of 34 of metal, and 8 of oxygen, being their respective prime equivalents; or, in 100 parts, of 81 and 19.

The principal ores of zinc are, the sulphuret called _blende_, the silicate called _calamine_ and the sparry calamine, or the carbonate.

1. _Blende_ crystallizes in the garnet-dodecahedron; its fracture is highly conchoidal; lustre, adamantine; colours, black, brown, red, yellow, and green; transparent or translucent; specific gravity, 4. It is a simple sulphuret of the metal; and, therefore, consists, in its pure state, of 34 of zinc, and 16 of sulphur. It dissolves in nitric acid, with disengagement of sulphuretted hydrogen gas. It occurs in beds and veins, accompanied chiefly by galena, iron pyrites, copper pyrites, and heavy spar. There is a radiated variety found at Przibram, remarkable for containing a large proportion of cadmium. Blende is found in great quantities in Derbyshire and Cumberland, as also in Cornwall.

2. _Calamine_, or silicate of zinc, is divided into two species; the prismatic or electric calamine, and the rhomboidal; though they both agree in metallurgic treatment. The _first_ has a vitreous lustre, inclining to pearly; colour, white, but occasionally blue, green, yellow, or brown; spec. grav. 3·38. It often occurs massive, and in botroidal shapes. This species is a compound of oxide of zinc with silica and water; and its constituents are--zinc oxide, 66·37; silica, 26·23; water, 7·4; in 100 parts. Reduced to powder, it is soluble in dilute sulphuric or nitric acid, and the solution gelatinizes on cooling. It emits a green phosphorescent light before the blowpipe. The second species, or rhombohedral calamine, is a carbonate of zinc. Its specific gravity is 4·442, much denser than the preceding. It occurs in kidney-shaped, botroidal, stalactitic, and other imitative shapes; surface generally rough, composition columnar. Massive, with a granular texture, sometimes impalpable; strongly coherent. According to Smithson’s analysis, Derbyshire calamine consists of--oxide of zinc, 65·2; carbonic acid, 34·8; which coincides almost exactly with a prime equivalent of the oxide and acid, or 42 + 22 = 64.

The mineral genus called _zinc-ore_, or red oxide of zinc, is denser than either of the above, its spec. grav. being 5·432. It is a compound of oxide of zinc 88, and oxide of iron and manganese 12. It is found massive, of a granular texture, in large quantities, in several localities, in New Jersey. It is set free in several metallurgic processes, and occurs crystallized in six-sided prisms of a yellow colour, in the smelting-works of Kœnigshutte in Silesia, according to Mitscherlich.

The zinc ores of England, like those of France, Flanders, and Silesia, occur in two geological localities.

The first is in veins in the carboniferous or mountain limestone. The blende and the calamine most usually accompany the numerous veins of galena which traverse that limestone; though there are many lead mines that yield no calamine; and, on the other hand, there are veins of calamine alone, as at Matlock, whence a very considerable quantity of this ore is obtained.

In almost every point of England where that metalliferous limestone appears, there are explorations for lead and zinc ores. The neighbourhood of Alston-moor in Cumberland, of Castleton and Matlock in Derbyshire, and the small metalliferous belt of Flintshire, are peculiarly marked for their mineral riches. On the north side of the last county, calamine is mined in a rich vein of galena at Holywell, where it presents the singular appearance of occurring only in the ramifications that the lead vein makes from east to west, and never in those from north to south; while the blende, abundantly present in this mine, is found indifferently in all directions.

The second locality of calamine is in the magnesian limestone formation of the English geologists, the alpine limestone of the French, and the zechstein of the Germans. The calamine is disseminated through it in small contemporaneous veins, which, running in all directions, form the appearance of a network. These veins have commonly a thickness of only a few inches; but in certain cases they extend to four feet, in consequence of the union of several small ones into a mass. The explorations of calamine in the magnesian limestone, are situated chiefly on the flanks of the Mendip Hills, a chain which extends in a north-west and south-east direction, from the canal of Bristol to Frome. The calamine is worked mostly in the parishes of Phipham and Roborough, as also near Rickford and Broadfield-Doron, by means of a great multitude of small shafts. The miners pay, for the privilege of working, a tax of 1_l._ sterling per annum to the Lords of the Treasury; and they sell the ores, mixed with a considerable quantity of carbonate of lime, for 1_l._ per ton, at Phipham, after washing it slightly in a sieve. They are despatched to Bristol, where they receive a new washing, in order to separate the galena.

OF THE SMELTING OF THE ORES OF ZINC.

The greater part of the zinc works are situated in the neighbourhood of Birmingham and Bristol. The manufacture of brass, which has been long one of the staple articles of these towns, was probably the cause of the introduction of this branch of industry, at the period when brass began to be made by the direct union of copper with metallic zinc, instead of calamine. A few zinc furnaces exist also in the neighbourhood of Sheffield, amid the coal-pits surrounding that town. Bristol and Birmingham derive their chief supply of ores from the Mendip Hills and Flintshire; and Sheffield, from Alston-moor.

The calamine, freed from the galena by sorting with the hand, is calcined before its introduction into the smelting-furnaces, by being exposed, coarsely bruised, in reverberatory ovens, 10 feet long, and 8 broad, in a layer 6 inches thick. In some establishments the calcination is omitted, and the calamine, broken into pieces about the size of a pigeon’s egg, is mixed with its bulk of small coal.

Zinc is smelted in England, likewise from blende (sulphuret of zinc). This ore, after being washed, and broken into pieces of the size of a filbert, was sold a few years ago at the mine of Holywell for 3_l._ a ton, or half the price of calamine. It is roasted, without any other preparation, in reverberatory furnaces; which are about 8 feet wide, and 10 long; the distance between the roof and the sole being 30 inches, and the height of the fire-bridge 18. The layer of blende, which is placed on the hearth, is about 4 or 5 inches thick; and it is continually stirred up with rakes. One ton of it requires, for roasting, four tons of coals; and it suffers a loss of 20 per cent. The operation takes from 10 to 12 hours. The mixture of reducing consists of one-fourth part of the desulphuretted oxide, one-fourth of calcined calamine, and one-half part of charcoal; which affords commonly 30 per cent. of zinc.

The English furnaces for smelting zinc ores are sometimes quadrangular, sometimes round; the latter form being preferable. They are mounted with from 6 to 8 crucibles or pots (see _fig._ 1231.), arched over with a cupola _a_, placed under a conical chimney _b_, which serves to give a strong draught, and to carry off the smoke. In this cone there are as many doors _c_, _c_, _c_, as there are pots in the furnace; and an equal number of vents _d_, _d_, _d_, in the cupola, through which the smoke may escape, and the pots may be set. In the surrounding walls there are holes for taking out the pots, when they become unserviceable; after the pots are set, these holes are bricked up. The pots are heated to ignition in a reverberatory furnace before being set, and are put in by means of iron tong machinery supported upon two wheels, as is the case with glass-house pots, _e_, is the grate; _f_, the door for the fuel; _g_, the ash-pit. The pots _h_, _h_, _h_, have a hole in the centre of their bottom, which is closed with a wooden plug, when they are set charged with calamine, mixed with one-seventh of coal; which coal prevents the mixture from falling through the orifice, when the heat rises and consumes the plug. The sole of the hearth _i_, _i_, upon which the crucibles stand, is perforated under each of them, so that they can be reached from below; to the bottom orifice of the pot, when the distillation begins, a long sheet-iron pipe _k_, is joined, which dips at its end into a water-vessel _l_, for receiving in drops the condensed vapours of the zinc. The pot is charged from above, through an orifice in the lid of the pot, which is left open after the firing, till the bluish colour of the flame shows the volatilization of the metal; immediately whereupon the hole is covered with a fire-tile _m_. The iron tubes are apt to get obstructed during the distillation, and must therefore be occasionally cleared out with a redhot rod. When the distillation is finished, the iron pipes must be removed; the coaly and other contents of the pot cleared away. A pot lasts about four months upon an average. Five distillations may be made in the course of 14 days, in which from 6 to 10 tons of calamine may be worked up, and from 22 to 24 tons of coals consumed, with a product of two tons of zinc. The metal amounts to from 25 to 40 per cent. of the ore.

1, 2, is the level of the upper floor; 3, 4, level of the lower ceiling of the lower floor.

_Fig._ 1232., ground plan on the level of 1, 2: only one-half is here shown.

The zinc collected in this operation, is in the form of drops, and a very fine powder, mingled with some oxide. It must be melted in an iron pot or boiler, set in a proper furnace; and the oxide is skimmed off the surface, to be returned into the crucibles. The metal is, lastly, cast into square bars or ingots.

The crucibles are discharged at the end of each operation, by withdrawing the condenser, breaking with a rake the piece of charcoal which shuts their bottom, and then emptying them completely, by shaking their upper part. In replacing the condenser-pipe _k_ (see second pot from the right hand, _fig._ 1231), the flange at its top is covered with a ring of loam-lute, pressed against the conical bottom of the crucible, and secured in its place by means of two parallel rods _o_, _o_, which can be clamped by screws projecting horizontally from the vertical tunnel. See their places, indicated by two open dots near _o_, _o_.

A smelter and two labourers are employed in conducting a furnace; who make, with a mixture of equal parts of fire-clay, and cement of old pounds finely ground, the pots or crucibles, which last about four months. Five charges are made in 15 days; these work up from 6 to 10 tons of calamine, consume from 22 to 24 tons of coals, and produce 2 tons of zinc, upon an average. The following estimate of prices was made a few years ago:--

3 tons of calamine, at _£_6. _£_18 0 0 24 ditto coal, at 5_s._ 6 0 0 A smelter, at 2 guineas a week 2 2 0 Two labourers, each at 4_s._ per day 2 16 0 Incidental expenses 1 0 0 -------- _£_29 18 0

The calamine of Alston-moor, used at Sheffield, is not so rich; it produces at most only 25 per cent. of zinc. The coals are laid down at a cost of 5_s._ 8_d._ per ton; and the calamine laid down there 5_l._; whence the zinc will amount to 32_l._ 14_s._ per ton. The considerable importations of zinc from Belgium and Germany, for some years back, have caused a considerable fall in its price.

At Lüttich, where the calamine of Altenberg, near Aix-la-Chapelle, is smelted, a reduction furnace, containing long horizontal earthen tubes, is employed. The roasted calamine is finely ground, and mixed with from one-third to two-thirds its volume of coke or charcoal, broken to pieces the size of nuts.

_Fig._ 1233. represents this zinc furnace in elevation; and _fig._ 1234. in a vertical section through the middle. From the hearth to the bottom of the chimney it is 9 feet high, and the chimney itself is 18 or 20 feet high. _a_, is the ash-pit; _b_, the grate; _c_, the fireplace; _d_, the hearth; _e_, _e_, the laboratory; _f_, the upper arch, which closes in the laboratory; _f_, the second arch, which forms the hood-cap of the furnace; _g_, the chimney; _h_, the fire-wall, which rests against a supporting wall of the smelting-house. Through the vaulted hearth the flame of the fire draws through ten flues _i_, _i_, two placed in one line; betwixt these 5 pairs of draught openings, upon the sole of the hearth, the undermost earthen tubes _k_, immediately rest. The second and third rows of tubes _k_, _k_, lie in a parallel direction over each other, at about one inch apart; in the sixth row there are only two tubes; so that there are 22 tubes altogether in one furnace. At their two ends these tubes rest upon fire-tiles, which form, with the side-walls, a kind of checquer-work _l_, _l_. The tubes are 4 feet long, 4 to 5 inches in diameter within, 5/4 of an inch thick. The fire, which arrives at the laboratory through the flues _i_, _i_, plays round the tubes, and passes off through the apertures _m_, _m_, in both arches of the furnace, into the chimney. _n_, is an opening in the front wall between the two arches, which serves to modify the draught, by admitting more or less of the external air.

The two slender side walls _o_, _o_, of the furnace, are a foot distant from the chequer-work, so that on the horizontal iron bars _q_, _q_, supported by the hooks _p_, _p_, the iron receivers _r_, _r_, may have room to rest at their fore part. These receivers are conical pipes of cast iron, 1-1/2 foot long, posteriorly 1-1/2 inch, and anteriorly 1 inch wide at the utmost. After the earthen tubes have been filled with the ore to be smelted, these conical pipes are luted to them in a slightly slanting position. These cones last no more than three weeks; and are generally lengthened with narrow-mouthed wrought-iron tubes, to prevent the combustion of the zinc, by contact of air. When the furnace is in activity, a blue flame is to be seen at the mouths of all these pipes. Every two hours the liquefied metal is raked out into a shovel placed beneath; and in 12 hours the charge is distilled; after which the tubes are cleared out, and re-charged. 100 pounds of metallic zinc are the product of one operation. It is remelted at a loss of 10 per cent., and cast into moulds for sale.

_Fig._ 1235. is a longitudinal section of the furnace for calcining calamine in Upper Silesia; _fig._ 1236. is a ground-plan of the furnace. _a_, is the orifice in the vault or dome, for the introduction of the ore; _b_, _b_, apertures in the side-walls, shut with doors, through which the matter may be turned over; _c_, the chimney; _d_, the fire-bridge; _e_, the grate; _f_, the feed opening of the fire, the fuel being pitcoal. The calamine is stirred about every hour; and after being well calcined during 5 or 6 hours, it is withdrawn; and a new charge is put in. These Silesian furnaces admit of 30 cwt. at a time; and for roasting every 100 cwt. 15 Prussian bushels of fuel, equal to 23 English bushels, are employed. These calcining furnaces are sometimes built alongside of the zinc smelting-furnaces, and are heated by the waste flame of the latter. The roasting is performed in the Netherlands in shafts, like small blast iron-furnaces, called schachtofen.

The hearth _a_, in _figs._ 1237, 1238., is constructed for working with 5 muffles, one of which is long, and four short. The muffles are made upon moulds, of fire-clay mixed with ground potsherds. The receivers are stoneware bottles. The grate is 10 inches beneath the level of the hearth. _b_, the fire-bridge, is proportionally high, to diminish the force of the flame upon the hearth, that it may not strike the muffles. _c_, is the opening through which the muffles are put in and taken out; during the firing it is partly filled with bricks, so that the smoke and flame may escape between them; _d_, _d_, are openings for adjusting the positions of the muffles; _e_, cross hoops of iron, to strengthen the brick arch; _f_, is a bed of sand under the sole of the hearth. During the first two days, the fire is applied under the grating; the heat must be very slowly raised to redness, at which pitch it must be maintained during two days. From 8 to 10 days are required for the firing of the muffles.

The furnace shown in _figs._ 1239, 1240, 1241. is for the melting of the metallic zinc. _Fig._ 1240. is a front view; _fig._ 1239. a transverse section; _fig._ 1241. a view from above: _a_, is the fire-door; _b_, the grate; _c_, the fire-bridge; _d_, the flue; _e_, the chimney; _f_, _f_, _f_, cast-iron melting-pots, which contain each about 10 cwt. of the metal. The heat is moderated by the successive addition of pieces of cold zinc. The inside of the pots should be coated with loam, to prevent the iron being attacked by the zinc. When the zinc is intended to be laminated, it should be melted with the lowest possible heat, and poured into hot moulds.

When the zinc ores contain cadmium, this metal distils over in the form of brown oxide, with the first portions, being more volatile than zinc.

Under BRASS and COPPER, the most useful alloys of zinc are described. The sulphate, vulgarly called white vitriol, is made from the sulphuret, by roasting it gently, and then exposing it upon sloping terraces to the action of air and moisture, as has been fully detailed under SULPHATE OF IRON. The purest sulphate of zinc is made by dissolving the metal in dilute sulphuric acid, digesting the solution over some of the metal, filtering, evaporating, and crystallizing.

Sulphate of zinc is added as a drier to japan varnishes.

The ordinary zinc found in the market is never pure; but contains lead, cadmium, arsenic, copper, iron, and carbon; from some of which, it may be freed in a great degree by distillation; but even after this process it retains a little lead, with all the arsenic and cadmium. The separation of the latter is described under CADMIUM. Zinc, free from other metals, may be obtained by distilling a mixture of charcoal and its subcarbonate, precipitated from the crystallized sulphate by carbonate of soda. By holding a porcelain saucer over the flame of hydrogen produced from the action of dilute sulphuric acid upon any sample of the zinc of commerce, the presence of arsenic in it may be made manifest by the deposit of a gray film of the latter metal. Antimony, however, produces a somewhat similar effect to arsenic.

Zinc is extensively employed for making water-cisterns, baths, spouts, pipes, plates for the zincographer, for voltaic batteries, filings for fire-works, covering roofs, and a great many architectural purposes, especially in Berlin; because this metal, after it gets covered with a thin film of oxide or carbonate, suffers no further change by long exposure to the weather. One capital objection to zinc as a roofing material, is its combustibility.

Chloride of zinc has been recently used with great advantage as an escharotic for removing cancerous tumours, and healing various ill-constitutioned ulcers. It, as also the nitrate, forms an ingredient in the resist pastes for the pale blues of the indigo vat.

Spelter (zinc) imported for home consumption--in 1835, 52,604 cwts.; in 1836, 47,406 cwts. Duty,--in cakes, 2_s._; not in cakes, 10_s._ per cwt.

THE END.

LONDON: Printed by A. SPOTTISWOODE New-Street-Square

Alphabetical List of Articles.

ABB-WOOL -- ACETATE -- ACETATE OF ALUMINA -- ACETIC ACID -- ACETIMETER -- ACETONE -- ACID OF ARSENIC -- ACIDS -- ACROSPIRE -- ADDITIONS -- ADIPOCIRE -- ADIT -- ADULTERATION -- ÆTHER -- AFFINITY -- AGARIC -- AGATE -- AIR -- ALABASTER -- ALBUM GRÆCUM -- ALCARAZZAS -- ALCOHOL -- ALE -- ALEMBIC -- ALEMBROTH -- ALGAROTH -- ALIZARINE -- ALKALI -- ALKALIMETER -- ALKANA -- ALKANET -- ALLIGATION -- ALLOY -- ALMOND -- ALMOND OIL -- ALOE -- ALUDEL -- ALUM -- AMADOU -- AMALGAM -- AMALGAMATION -- AMBER -- AMBERGRIS -- AMIANTHUS -- AMMONIA -- AMMONIAC -- AMORPHOUS -- ANALYSIS -- ANCHOR -- ANIMÉ -- ANKER -- ANNEALING or NEALING -- ANNOTTO -- ANTHRACITE -- ANTIGUGGLER -- ANTIMONY -- ANTISEPTICS -- ANVIL -- AQUA REGIA -- AQUA VITÆ -- AQUAFORTIS -- ARCHIL -- ARDENT SPIRIT -- AREOMETER OF BAUMÉ -- ARGILLACEOUS EARTH -- ARGOL -- ARMS -- ARRACK -- ARROW ROOT -- ARSENIC -- ARTESIAN WELLS -- ASPHALTUM -- ASSAY and ASSAYING -- ATOMIC WEIGHTS or ATOMS -- ATTAR OF ROSES -- AURUM MUSIVUM -- AUTOMATIC -- AUTOMATON -- AXE -- AXLES -- AXUNGE -- AZOTIZED -- AZURE

BABLAH -- BAGASSE -- BAKING -- BALANCE -- BALSAMS -- BANDANNA -- BARBERRY -- BARILLA -- BARIUM -- BARK OF OAK -- BARLEY -- BARM -- BARYTA or BARYTES -- BASSORINE -- BATHS -- BDELLIUM -- BEER -- BEET-ROOT SUGAR -- BELL-METAL -- BELLOWS -- BEN OIL -- BENGAL STRIPES -- BENJAMIN or BENZOIN -- BERLIN BLUE -- BERRIES OF AVIGNON -- BERYL -- BEZOAR -- BILE -- BIRDLIME -- BISMUTH -- BISTRE -- BITTER PRINCIPLE -- BITUMEN, or ASPHALTUM -- BLACK DYE -- BLACK PIGMENT -- BLEACHING -- BLENDE -- BLOCK MANUFACTURE -- BLOOD -- BLOWING MACHINE -- BLOWPIPE -- BLUE DYES -- BLUE PIGMENTS -- BLUE VITRIOL -- BOMBAZINE -- BONE BLACK -- BONES -- BOOKBINDING -- BORAX -- BOTTLE MANUFACTURE -- BOUGIE -- BRACES -- BRAIDING MACHINE -- BRAN -- BRANDY -- BRASS -- BRAZIL-WOOD -- BRAZING -- BREAD -- BRECCIA -- BREWING -- BRICK -- BRIMSTONE -- BRITISH GUM -- BROMINE -- BRONZE -- BROWN DYE -- BRUSHES -- BUTTER -- BUTTER OF CACAO -- BUTTON MANUFACTURE

CABLE -- CACAO, BUTTER OF -- CADMIUM -- CAFEINE -- CAJEPUT OIL -- CALAMANCO -- CALAMINE -- CALC-SINTER -- CALC-TUFF -- CALCAREOUS EARTH -- CALCAREOUS SPAR -- CALCEDONY -- CALCHANTUM -- CALCINATION -- CALCIUM -- CALCULUS -- CALENDER -- CALICO-PRINTING -- CALOMEL -- CALORIC -- CALORIFÈRE OF WATER -- CAMBRIC -- CAMLET OR CAMBLET -- CAMPHOR, or CAMPHIRE -- CAMWOOD -- CANDLE -- CANE-MILL -- CANNON -- CANVASS -- CAOUTCHOUC, GUM-ELASTIC, OR INDIAN-RUBBER -- CAPERS -- CAPSTAN -- CARAT or CARACT -- CARBON -- CARBONATE OF AMMONIA -- CARBONATED WATER -- CARBONATES -- CARBONIC ACID -- CARBONIC OXIDE -- CARBUNCLE -- CARBURET OF SULPHUR -- CARBURETTED HYDROGEN -- CARD CUTTING -- CARDS -- CARDS, PLAYING -- CARMINE -- CARPET -- CARTHAMUS -- CASE-HARDENING -- CASHMERE or CACHEMERE -- CASK -- CASSAVA -- CASSIS -- CASTING OF METALS -- CASTOR -- CASTOR OIL -- CASTOR or CASTOREUM -- CASTORINE -- CATECHU -- CATGUT -- CATHARTINE -- CAUSTIC -- CAVIAR -- CAWK -- CEDRA -- CELESTINE -- CEMENTATION -- CEMENTS -- CERASIN -- CERATE -- CERINE -- CERIUM -- CERUSE -- CETINE -- CHAINWORK -- CHALK -- CHALK--Black -- CHALK--French -- CHALK--Red -- CHARCOAL -- CHICA -- CHIMNEY -- CHINTZ -- CHLORATE OF POTASH -- CHLORATES -- CHLORIC ACID -- CHLORINE -- CHLOROMETRY -- CHOCOLATE -- CHROMATES -- CHROMIC ACID -- CHROMIUM -- CINNABAR -- CINNAMON -- CITRIC ACID -- CIVET -- CLAY -- CLOTH-BINDING -- CLOTH, MANUFACTURE OF -- COBALT -- COCCULUS INDICUS, or Indian berry -- COCHINEAL -- COCOA, STEARINE, AND ELAINE -- COFFEE -- COKE -- COLCOTHAR OF VITRIOL -- COLOPHANY -- COLOURING MATTER -- COLUMBIUM -- COLZA -- COMB -- COMBINATION -- COMBUSTIBLE -- COMBUSTION -- COMPOUND COLOURS -- CONCRETE -- CONGELATION -- COOLING OF FLUIDS -- COPAL -- COPPER -- COPPER, Statistics of -- COPPERAS -- CORAL -- CORK -- CORROSIVE SUBLIMATE -- CORUNDUM; or Telesie -- COTTON DYEING -- COTTON MANUFACTURE -- COURT PLASTER -- CRAPE -- CRAYONS -- CRAYONS, lithographic -- CREOSOTE -- CRUCIBLES -- CRYSTAL -- CUDBEAR -- CUPELLATION -- CURRYING OF LEATHER -- CUTLERY -- CYANATES -- CYANHYDRIC Acid -- CYANIDES -- CYANIDES, FERRO -- CYANOGEN -- CYDER

DAHLINE -- DAMASCUS BLADES -- DAMASK -- DAMASKEENING -- DAMASSIN -- DAMPS -- DAPHNINE -- DATOLITE -- DECANTATION -- DECOCTION -- DECOMPOSITION -- DECREPITATION -- DEFECATION -- DEFLAGRATION -- DELIQUESCENT -- DELPHINIA -- DEPHLEGMATION -- DEPHLOGISTICATED -- DEPILATORY -- DETONATION -- DEUTOXIDE -- DEXTRINE -- DIAMOND -- DIAMOND MICROSCOPES -- DIAMONDS, cutting of -- DIAPER -- DIASTASE -- DIES FOR STAMPING -- DIGESTER -- DIMITY -- DISTILLATION -- DOCIMACY -- DORNOCK -- DRAGON’S BLOOD -- DRUGGET -- DRYING HOUSE -- DUCTILITY -- DUNGING -- DYEING

EARTHS -- EAU DE COLOGNE -- EAU DE LUCE -- EBULLITION -- EDGE-TOOLS -- EDULCORATE -- EFFERVESCENCE -- EFFLORESCENCE -- EGGS, HATCHING -- EIDER-DOWN -- ELAINE -- ELASTIC BANDS -- ELECTIVE AFFINITY -- ELEMENTS -- ELEMI -- ELUTRIATE -- EMBALMING -- EMBOSSING CLOTH -- EMBOSSING WOOD -- EMBROIDERING MACHINE -- EMERALD -- EMERY -- EMPYREUMA -- ENAMELS -- EPSOM SALTS -- EQUIVALENTS, CHEMICAL -- ESSENCE D’ORIENT -- ESSENCES -- ETCHING Varnish -- ETHER -- ETHER, Acetic -- ETHIOPS -- EUDIOMETER -- EVAPORATION -- EXPANSION -- EXTRACTS

FAHLERZ -- FAINTS -- FAN -- FARINA -- FATS -- FAULTS -- FEATHERS -- FECULA -- FELSPAR -- FELTING -- FERMENT -- FERMENTATION -- FERROCYANATE, or, FERROCYANIDE -- FERROPRUSSIATES -- FIBRE, VEGETABLE -- FIBRINE -- FILE -- FILLIGREE -- FILTRATION -- FIRE ARMS, MANUFACTURE OF -- FIRE-DAMP -- FIRE-WORKS -- FISH-HOOKS -- FLAKE WHITE -- FLAME -- FLANNEL -- FLAX -- FLINT -- FLOSS -- FLOSS-SILK -- FLOUR -- FLOUR OF WHEAT, Adulterations of, to Detect -- FLOWERS -- FLOWERS, ARTIFICIAL, MANUFACTURE OF -- FLUATES -- FLUOR SPAR -- FLUX -- FLY POWDER -- FODDER -- FONDUS -- FORGE -- FORMIATES -- FORMIC ACID -- FORMULÆ, CHEMICAL -- FOUNDING -- FOUNTAIN -- FOXING -- FRANKFORT BLACK -- FREEZING -- FRENCH BERRIES -- FRICTION, counteraction of -- FRIT -- FUEL -- FULGURATION -- FULLER’S EARTH -- FULLING -- FULLING MILL -- FULMINATES -- FULMINIC ACID -- FUMIGATION -- FUR -- FURNACE OF ASSAY -- FUSIBILITY -- FUSIBLE METAL -- FUSTET -- FUSTIAN -- FUSTIC

GABRONITE -- GADOLINITE -- GALACTOMETER, or LACTOMETER -- GALBANUM -- GALENA -- GALIPOT -- GALL OF ANIMALS, or OX-GALL, purification of -- GALL OF GLASS -- GALL-NUTS, or GALLS -- GALLATES -- GALLIC ACID -- GALLIPOLI OIL -- GALVANIZED IRON -- GAMBOGE -- GANGUE -- GARNET -- GAS -- GAS-HOLDER -- GAS-LIGHT -- GASOMETER -- GAUZE WIRE CLOTH -- GAY-LUSSITE -- GELATINE -- GEMS -- GEOGNOSY -- GERMAN SILVER -- GERMINATION -- GIG MACHINES -- GILDING -- GIN, or Geneva, -- GINNING -- GLANCE COAL -- GLASS -- GLASS CUTTING AND GRINDING -- GLASS MAKING -- GLAUBER SALT -- GLAZES -- GLAZIER -- GLOVE MANUFACTURE -- GLOVE-SEWING -- GLUCINA -- GLUE -- GLUTEN -- GLYCERINE -- GNEISS -- GOLD -- GONG-GONG; or tam-tam -- GONIOMETER -- GRADUATOR -- GRANITE -- GRANULATION -- GRAPHITE -- GRAUWACKE or GREYWACKE -- GRAY DYE -- GREEN DYE -- GREEN PAINTS -- GREEN VITRIOL -- GUAIAC -- GUANO -- GUM -- GUM RESINS -- GUNPOWDER -- GYPSUM

HADE -- HAIR -- HAIR PENCILS OR BRUSHES -- HALOGENE -- HANDSPIKE -- HARDNESS -- HARTSHORN, SPIRIT OF -- HAT MANUFACTURE -- HATCHING OF CHICKENS -- HEALDS -- HEARTH -- HEAT -- HEAT-REGULATOR -- HEAVY SPAR -- HECKLE -- HELIOTROPE -- HEMATINE -- HEMATITE -- HEMP -- HEPAR -- HEPATIC AIR -- HERMETICAL SEAL -- HIDE -- HIRCINE -- HOG’s LARD -- HONEY -- HONEY-STONE -- HOP -- HORDEINE -- HORN -- HORNSILVER -- HORNSTONE -- HORSE POWER -- HOSIERY -- HOT-FLUE -- HYDRATES -- HYDRAULIC PRESS -- HYDRIODIC ACID -- HYDROCHLORIC ACID -- HYDROGEN -- HYDROMETER -- HYDROSULPHURETS -- HYMEN[OE]A COURBARIL -- HYOSCIAMUS NIGER -- HYPEROXYMURIATES -- HYPOSULPHATES; HYPOSULPHITES

ICEHOUSE -- IMPERMEABLE -- INCOMBUSTIBLE CLOTH -- INCUBATION, ARTIFICIAL -- INDIAN RUBBER -- INDIGO -- INK -- INULINE -- IODINE -- IRIDIUM -- IRON -- ISINGLASS, or Fish-glue -- ISLAND MOSS -- IVORY -- IVORY BLACK

JACK -- JACK and JACK-SINKERS -- JACK-BACK -- JACQUARD -- JADE -- JAPANNING -- JASPER -- JELLY, ANIMAL -- JELLY, VEGETABLE -- JET -- JEWELLERY, Art of.

KALI -- KAOLIN -- KARABÉ -- KELP -- KERMES -- KILLAS -- KILN -- KINIC ACID -- KINO -- KIRSCHWASSER -- KNOPPERN -- KOUMISS

LABDANUM or LADANUM -- LABRADORITE, OPALINE or LABRADORE FELSPAR -- LABYRINTH -- LAC, LAC-DYE -- LACCIC ACID -- LACCINE -- LACE MANUFACTURE -- LACQUER -- LACTIC ACID -- LACTOMETER -- LAKES -- LAMINABLE -- LAMIUM ALBUM -- LAMP OF DAVY -- LAMP-BLACK -- LAMPATES and LAMPIC ACID -- LAMPS -- LAPIDARY, Art of -- LAZULITE -- LEAD -- LEAD-SHOT -- LEATHER -- LEDUM PALUSTRE -- LEGUMINE -- LEMONS -- LEUCINE -- LEUCITE -- LEVIGATION -- LEWIS -- LIAS -- LIBAVIUS, LIQUOR OF -- LICHEN. -- LIGNEOUS MATTER -- LIGNITE -- LILAC DYE -- LIMESTONE -- LINEN -- LINSEED -- LIQUATION -- LIQUEURS, LIQUORISTE -- LIQUID AMBER -- LITHARGE -- LITHIA -- LITHIUM -- LITHOGRAPHY -- LITMUS -- LIXIVIATION -- LOADSTONE, MAGNETIC IRON-STONE -- LOAM -- LODE -- LOGWOOD -- LOOM -- LUBRICATION -- LUPININE -- LUPULINE -- LUTE -- LUTEOLINE -- LYCOPODIUM CLAVATUM -- LYDIAN STONE

MACARONI -- MACE -- MACERATION -- MACLE -- MADDER -- MADREPORES -- MAGISTERY -- MAGISTRAL -- MAGMA -- MAGNANIER -- MAGNESIA -- MAGNESIA, NATIVE -- MAGNESIAN LIMESTONE -- MAGNESITE -- MAGNET, NATIVE -- MAHALEB -- MALACHITE -- MALATES -- MALIC ACID -- MALLEABILITY -- MALT -- MALT KILN -- MALTHA -- MANGANESE -- MANGLE -- MANIOC -- MANNA -- MARBLE -- MARCASITE -- MARGARATES -- MARGARIC ACID -- MARINE ACID -- MARINE SALT -- MARL -- MARQUETRY -- MARTIAL -- MASSICOT -- MASTIC -- MATRASS -- MATTE -- MEADOW ORE -- MEDALS -- MEERSCHAUM -- MELLITE -- MELLITIC ACID -- MELLON -- MENACHANITE -- MERCURY or QUICKSILVER -- MERCURY, BICHLORIDE OF -- MERCURY, PROTOCHLORIDE OF -- METALLURGY -- METALS -- METEORITES -- METHYLÈNE -- MICA -- MICROCOSMIC SALT -- MILK -- MILL-STONE, or BUHR-STONE -- MINERAL WATERS -- MINES -- MINIUM -- MINT -- MIRRORS -- MISPICKEL -- MOHAIR -- MOIRÉE METALLIQUE -- MOLASSE -- MOLASSES -- MOLYBDENUM -- MORDANT (adhesive) -- MORDANT (colouring) -- MOROCCO -- MORPHIA -- MORTAR, HYDRAULIC -- MOSAIC -- MOSAIC GOLD -- MOTHER OF PEARL -- MOTHER-WATER -- MOUNTAIN SOAP -- MUCIC ACID -- MUCILAGE -- MUFFLE -- MUNDIC -- MUNJEET -- MURIATES -- MURIATIC or HYDROCHLORIC ACID -- MUSK -- MUSLIN -- MUST -- MUSTARD -- MUTAGE -- MYRICINE -- MYRRH

NACARAT -- NAILS, MANUFACTURE OF -- NANKIN -- NAPHTHA, or ROCK-OIL -- NAPHTHALINE -- NAPLES YELLOW -- NATRON -- NEALING -- NEB-NEB -- NEEDLE MANUFACTURE -- NEROLI -- NET -- NEUTRALIZATION -- NICARAGUA WOOD -- NICKEL -- NICOTIANINE -- NICOTINE -- NITRATE OF AMMONIA -- NITRATE OF LEAD -- NITRATE OF POTASH -- NITRATE OF SILVER -- NITRATE OF SODA -- NITRATE OF STRONTIA -- NITRIC ACID -- NITRO-MURIATIC ACID -- NITROGEN GAS, or AZOTE -- NITROGEN, DEUTOXIDE OF -- NITROGEN, PROTOXIDE OF -- NITROUS ACID -- NOPAL -- NUT OIL -- NUTMEG -- NUX VOMICA

OAK BARK -- OATS -- OBSIDIAN -- OCHRE -- OIL OF VITRIOL -- OILS -- OILS, VOLATILE OR ESSENTIAL; Manufacture of -- OLEATES -- OLEFIANT GAS -- OLEIC ACID -- OLEINE -- OLIBANUM -- OLIVE OIL -- ONYX -- OOLITE -- OOST, or OAST -- OPAL -- OPERAMETER -- OPIUM -- OPOBALSAM -- OPOPONAX -- ORANGE DYE -- ORCINE -- ORES -- ORPIMENT -- ORYCTNOGNOSY -- OSMIUM -- OSTEOCOLLA -- OXALATES -- OXALIC ACID -- OXIDES -- OXISELS -- OXYGEN

PACKFONG -- PACO, or PACOS -- PADDING MACHINE -- PAINT -- PAINTS, GRINDING OF -- PAINTS, VITRIFIABLE -- PALLADIUM -- PALM OIL -- PAPER CUTTING -- PAPER-HANGINGS -- PAPER, MANUFACTURE OF -- PARAFFINE -- PARCHMENT -- PARTING -- PASTEL (colour) -- PASTEL (crayon) -- PASTES, or FACTITIOUS GEMS -- PASTILLE (perfumery) -- PASTILLE (tablet) -- PE-TUNT-SE -- PEARLASH -- PEARLS -- PEARLS, ARTIFICIAL -- PEARLWHITE -- PECTIC ACID -- PECTINE -- PELTRY -- PENCIL MANUFACTURE -- PENS, STEEL -- PEPPER -- PERFUMERY, ART OF -- PERRY -- PERSIAN BERRIES -- PETROLEUM -- PEWTER, PEWTERER -- PHOSPHORIC ACID -- PHOSPHORUS -- PICAMARE -- PICROMEL -- PICROTOXINE -- PIGMENTS, VITRIFIABLE -- PIMENTO -- PIN MANUFACTURE -- PINCHBECK -- PINE-APPLE YARN and CLOTH -- PINEY TALLOW -- PIPERINE -- PITCH of wood-tar -- PITCH, MINERAL -- PITCOAL -- PITCOAL, COKING OF -- PITTACALL -- PLASTER -- PLASTER OF PARIS -- PLATED MANUFACTURE -- PLATINA-MOHR -- PLATINUM -- PLUMBAGO -- PLUSH -- POINT NET -- PORCELAIN -- PORPHYRY -- PORTER -- PORTLAND STONE -- POTASH, or POTASSA -- POTASSIUM -- POTATO -- POTTERY, PORCELAIN. -- PRECIPITATE -- PRECIPITATION -- PRESS, HYDRAULIC -- PRINCE’S METAL, or Prince Rupert’s metal -- PRINTING INK -- PRINTING MACHINE -- PRUSSIAN BLUE, and PRUSSIATE OF POTASH -- PUMICE-STONE -- PUOZZOLANA -- PURPLE OF CASSIUS, Gold purple -- PURPLE OF MOLLUSCA -- PURPURIC ACID -- PURPURINE -- PUTREFACTION and its prevention -- PYRITES -- PYRO-ACETIC SPIRIT -- PYROLIGNOUS ACID -- PYROLIGNOUS or PYROXILIC SPIRIT -- PYROMETER -- PYROPHORUS -- PYROTECHNY -- PYROXILINE

QUARTATION -- QUARTZ -- QUASSIA -- QUEEN’s WARE -- QUEEN’s YELLOW -- QUERCITRON -- QUICKLIME -- QUICKSILVER -- QUILL -- QUININA -- QUINTESSENCE

RAISINS -- RAPE-SEED -- RASP, MECHANICAL -- RATAFIA -- REALGAR -- RECTIFICATION -- RED LIQUOR -- REED -- REFINING OF GOLD AND SILVER -- REFRIGERATION OF WORTS, &c. -- REGULUS -- RESIN, KAURI or COWDEE -- RESINS -- RETORT -- REVERBERATORY FURNACE -- RHODIUM -- RIBBON MANUFACTURE -- RICE -- RICE CLEANING -- RIFLE -- RINSING MACHINE -- ROCKETS -- ROLLING-MILL -- ROPE-MAKING -- ROSIN GAS -- ROSIN, or COLOPHANY -- ROTTEN-STONE -- ROUGE -- RUBY -- RUM -- RUST -- RYE

SAFETY LAMP -- SAFFLOWER -- SAFFRON -- SAGO -- SAL AMMONIAC -- SAL PRUNELLA -- SAL VOLATILE -- SALAMSTONE -- SALEP, or SALOUP -- SALICINE -- SALT OF AMBER -- SALT OF LEMONS -- SALT OF SATURN -- SALT OF SODA -- SALT OF SORREL -- SALT OF TARTAR -- SALT OF VITRIOL -- SALT PERLATE -- SALT, EPSOM -- SALT, MICROCOSMIC -- SALT, SEA, or CULINARY; Chloride of sodium -- SALT, SEDATIVE -- SALTPETRE -- SALTS -- SAND -- SANDAL or RED SAUNDERS WOOD -- SANDARACH -- SAPAN WOOD -- SARD -- SATIN -- SATURATION -- SCALIOLA -- SCARLET DYE -- SCHEELE’S GREEN -- SCHWEINFURTH GREEN -- SCOURING -- SEA WATER -- SEAL ENGRAVING -- SEALING-WAX -- SEGGAR, or SAGGER -- SELENIUM -- SELTZER WATER -- SEPIA -- SEPTARIA -- SERPENTINE -- SHAFT -- SHAGREEN -- SHALE, or SLATE-CLAY -- SHAMOY LEATHER -- SHEATHING OF SHIPS -- SHELLAC -- SIENITE -- SILICA and SILICON -- SILICATES -- SILICON -- SILK MANUFACTURE -- SILKWORM GUT -- SILVER -- SILVER LEAF -- SILVERING -- SIMILOR -- SINGEING OF WEBS -- SKIN -- SLAG -- SLATES -- SMALL WARES -- SMALT -- SMELTING -- SOAP -- SOAPSTONE -- SODA-WATER -- SODA, Caustic soda -- SODA, CARBONATE OF -- SODIUM -- SOLDERING -- SOOT -- SORBIC ACID -- SOY -- SPECIFIC GRAVITY -- SPECULUM METAL -- SPERMACETI -- SPIRIT OF AMMONIA -- SPIRIT OF WINE -- SPIRITS, VINOUS -- SPONGE -- SPOON MANUFACTURE -- STAINED GLASS -- STAMPING OF METALS -- STARCH -- STARCHING AND STEAM-DRYING APPARATUS -- STEAM -- STEARIC ACID, improperly called STEARINE -- STEARINE COLD PRESS -- STEATITE -- STEEL -- STEREOTYPE PRINTING -- STILL -- STOCKING MANUFACTURE -- STONE -- STONE, ARTIFICIAL -- STONEWARE -- STORAX, STYRAX -- STOVE -- STRASS -- STRAW-HAT MANUFACTURE -- STRETCHING MACHINE -- STRONTIA -- STRYCHNIA -- STUCCO -- SUBERIC ACID -- SUBLIMATE -- SUBLIMATION -- SUBSALT -- SUCCINIC ACID, Acid of Amber -- SUGAR -- SUGAR OF LEAD -- SULPHATE OF ALUMINA AND POTASSA -- SULPHATE OF AMMONIA -- SULPHATE OF BARYTA -- SULPHATE OF COPPER -- SULPHATE OF IRON -- SULPHATE OF LIME -- SULPHATE OF MAGNESIA, Epsom Salt -- SULPHATE OF MANGANESE -- SULPHATE OF MERCURY -- SULPHATE OF POTASSA -- SULPHATE OF SODA -- SULPHATE OF ZINC -- SULPHATES -- SULPHITES -- SULPHOSELS -- SULPHUR; Brimstone -- SULPHURATION -- SULPHURETTED HYDROGEN -- SULPHURIC ACID, Vitriolic Acid, or Oil of Vitriol -- SUMACH -- SWEEP-WASHER -- SYNTHESIS -- SYRUP

TABBYING, or WATERING -- TACAMAHAC -- TAFFETY -- TAFIA -- TALC -- TALLOW -- TALLOW, PINEY -- TAMPING -- TAN, or TANNIC ACID -- TANNING -- TANTALUM -- TAPESTRY -- TAPIOCA -- TAR -- TARRAS -- TARTAR -- TARTARIC ACID -- TARTRATES -- TAWING -- TEA -- TEASEL -- TEETH -- TELLURIUM -- TERRA DI SIENA -- TERRA-COTTA -- TESTS -- TEXTILE FABRICS -- THENARD’S BLUE, or COBALT BLUE -- THERMOMETER -- THERMOSTAT -- THIMBLE -- THORINA -- THREAD MANUFACTURE -- TILES -- TILTING OF STEEL -- TIN -- TIN MORDANTS -- TIN-GLASS -- TIN-PLATE -- TINCAL -- TINCTORIAL MATTER -- TINCTURE -- TITANIUM -- TOBACCO -- TOBACCO-PIPES -- TODDY -- TOLU -- TOMBAC -- TONKA BEAN -- TOPAZ -- TORTOISE-SHELL -- TOUCH-NEEDLES, and TOUCH-STONE -- TOW -- TRAGACANTH, GUM -- TRAVERTINO -- TREACLE -- TRIPOLI -- TUFA, or TUF -- TULA METAL -- TUNGSTEN -- TURBITH MINERAL -- TURF -- TURKEY RED -- TURMERIC, Curcuma, Terra merita -- TURNSOLE -- TURPENTINE -- TURPENTINE, OIL OF -- TURQUOIS -- TUTENAG -- TYPE

ULTRAMARINE -- UMBER -- URANIUM -- URAO

VALONIA -- VANADIUM -- VANILLA -- VAPOUR -- VARNISH -- VEIN STONES, or GANGUES -- VEINS -- VELLUM -- VELVET -- VENETIAN CHALK -- VENTILATION -- VENUS -- VERATRINE -- VERDIGRIS -- VERDITER, or BLUE VERDITER -- VERDITER, or BREMEN GREEN -- VERMICELLI -- VERMILLION, or Cinnabar -- VINEGAR MANUFACTORY, BY MALT -- VIOLET DYE -- VITRIFIABLE COLOURS -- VITRIOL

WACKE -- WADD -- WADDING -- WAFERS -- WALNUT HUSKS, or PEELS -- WARP -- WASH -- WASHING -- WATER-PROOF CLOTH -- WATERING OF STUFFS -- WATERS, MINERAL -- WAX -- WAX, MINERAL, or Ozocerite, -- WEAVING -- WEFT -- WELD -- WELDING -- WELLS, ARTESIAN -- WHALEBONE -- WHEAT -- WHEEL CARRIAGES -- WHETSLATE -- WHEY -- WHISKEY -- WHITE LEAD -- WICK -- WINCING-MACHINE -- WINE -- WINE-STONE -- WINE, FAMILY -- WIRE-DRAWING -- WOAD -- WOLFRAM -- WOOD -- WOOF -- WOOLLEN MANUFACTURE -- WOOTZ -- WORT -- WOULFE’S APPARATUS

XANTHINE

YEAST -- YELLOW DYE -- YELLOW, KING’S -- YTTRIA

ZAFFRE -- ZEDOARY -- ZIMOME -- ZINC -- ZIRCON -- ZIRCONIA

Transcriber’s Notes

General

This e-text follows the text of the original work, including inconsistencies in spelling, hyphenation, capitalisation and typography. In particular, the following have not been standardised or corrected (except when mentioned below):

- the two types of fractions used (2-1/2 and 1-10th, for example);

- errors in calculations (for example, constituent parts that do not add up to the total given);

- articles that are not in alphabetical order have not been moved (note that I and J are considered to be equivalent, as in Jasper -- Icehouse -- Jelly);

- missing reference letters/figures in illustrations;

- inconsistent numbering of sections and paragraphs (for example, there may be a paragraph number 1, but no number 2 or further; there may be a section number II, but no number I).

Some illustrations are missing from the original and are not referred to in the text (Figs. 57, 372), others are provided in the original work, but not discussed or described. Fig. 93 is not present in the original, but is described in the text. The original has two illustrations numbered 384; the second one (on page 464) has been renamed 384*. Figures 496/497 and 498/499 are remarkably similar, as is their description.

Remarks on the text

Fontanier and Fontanieu probably refer to the same person.

The text occasionally gives ohm and aime as inits of volume; these are probably aams or ames (circa 30-36 imperial gallons).

There are several references to a table of elasticities of vapour; it is not clear which table is meant.

Page 16, table: the temperature 164° stands out from the other temperatures, and may be wrong (possibly error for 194°)

Page 16, The specific gravity of water at 60° being 1000, at 62° it is 99,981. This phrase contains at least one mistake: the intention might be specific gravities 100 and 99·981, respectively (see also the table following on page 21/22).

Page 19, table, first row, column 70°: 9991 does not fit in with the other data, this is possibly an error for 9981.

Page 25, table, first row (17°): 44·9 does not fit with the other data; this is possibly an error for 44·2; last row but one (24°): 693 does not fit with the other data; possibly an error for 993.

Page 26, table, row 20°: the last value was partly illegible in the original, this should probably be 68·4; row 22° the last decimal was illegible in the original, this should probably be 67·7 or 67·8.

Page 29, Lausania inermis: probably Lawsonia inermis.

Page 41, reference to Gems, cutting of: the article Gems refers to the article Lapidary for cutting of gems.

Page 46, Fig. 14, a plan of the same: Fig. 14 is a different side view.

Page 67, 1000 of a grain of silver: possibly an error for 1/1000 of a grain of silver.

Page 99, reference to Saccharometer: there is no article Saccharometer; the saccharometer is discussed in the article Beer only.

Page 111-112, description of location of elements relative to each other: the author has reversed left and right.

Page 118, See Oil of Ben: there is no such article; the only reference to Oil of Ben occurs on page 895 (table).

Page 150, teint, Germ.: probably error for teint, French.

Page 169, Fernambouc: the 16th century French name for Pernambuco.

Page 178, calculation: 315 loaves at 6d. give 7_l._ 17_s._ 6_d._, making the clear profit 11_s._ 10_d._

Page 225, Chloride of Lime: there is no such article; chloride of lime is discussed under Bleaching.

Page 249, reference to Mill: there is no such article; the article Sugar has a part on mills.

Page 339, first table: the first two columns do not add up to the sub-totals given; it is not clear whether this is due to errors in the data or to miscalculation.

Page 358, Fig. 337 and accompanying text: text and illustration do not seem to fit together, few of the parts mentioned appear in the figure.

Page 382, reference to Prussic Acid: the Dictionary does not have this article.

Page 392, the year 173: the last digit was missing from the original, and has been replaced with a tilde (173~). The 1858 enlarged edition gives 1730 as the year.

Page 396, by of a lever: possibly a word is missing (by means of a lever or similar).

Page 403, footnote [24]: 2198 should possibly read 1829.

Page 512, table Phosphorus: The two values in the last column are incompatible: the first should be one half of the second.

Page 522, about 6-1/2 per cent. upon: possibly a word (such as depending) is missing.

Page 564, second table: the totals do not always add up completely, and the meaning of some of the data is unclear.

Page 605, Abrabanya: should possibly be Abrudbánya

Page 632, dyeing of horse-hair: this is described in the same, not the next article.

Page 742, Bilin in Bohemia: also referred to as Billen and Billin.

Page 784, Houton-Libillardière: probably Jacques-Julien Houtou de La Billardière.

Page 876, The carriage is then again by the rotation ...: there is a verb missing from the text (advanced, moved forward, or similar).

Page 885, Nicaraca: possibly an error for Nicaragua.

Page 895, table, line 41: the specific gravity is likely to be a misprint.

Page 897: strychia: possibly an error for strychnia.

Page 920, three separate sheets: the three knives will cut four sheets.

Page 1093, table: dr. in the column Cochineal may be an error for oz.

Page 1151, reference to page 1041: there is no related information on this page.

Page 1204, arescence: possibly an error for acescence.

Page 1270, Then increase the gradually: a word is missing from the original (possibly heat or temperature).

Changes and corrections made

Some missing punctuation has been added and obvious minor typographical errors have been corrected silently.

Footnotes have been moved to under the paragraph etc. they refer to.

Illustrations have been moved to where they are first or most fully described, they are therefore not always given in numerical order (the original work does not always show them in numerical order either). Illustration numbers have been added to illustrations that lacked a number.

Multi-page tables have been changed to single tables; tables have been re-arranged or split; some tables are presented here with legends or table notes.

For the sake of consistency, the following changes have been made throughout the text:

- All references to illustration numbers in the text have been italicised (_Fig._ nnn etc.); reference letters in the text have been standardised to italics (for lower case letters) and capitals (for upper case letters).

- Apostrophes in French words have been closed with the following word where necessary.

- All decimal points have been changed to mid-dots, commas and dashes have been changed to mid-dots or vice versa where necessary.

- Accents on French words printed in capitals have been moved where necessary (for example E' has been changed to É).

- The Alphabetical List of Articles has been added.

- The German ...saure in nouns has been standardised to ...säure.

- The author uses the single and double dashed pound sign; both are represented here by the same symbol (£). All £/l. s. and d. (pound, shilling, pence) have been italicised for consistency.

Other changes:

Location Original document Changed to Page vi, table 201,773,872 204,773,872 Page 14 olëine oleine as elsewhere Page 15 Brongniard Brongniart Page 22, table, ·70042 ·00042 row ·82 ditto last line ·100 1·00 Page 49 αηθραξ ανθραξ Page 57 _a a_ A A as in illustration Page 69, Fig. 87 -- letter c added Page 75 Baume Baumé as elsewhere Page 84 -- 2. added before Balsams without benzoic acid Page 92 intersticial interstitial as else- where Page 109, second table 980 0·980 Page 112 the troughs u the troughs n as in the illustration Page 122 Breislack Breislak as elsewhere Page 144 sp. gr. 0837 sp. gr. 0·837 ditto sheeps’ wool sheep’s wool as else- where Page 167 fig. 165, between fig. 163. Between Fig. 162 _c_ _e_ Page 171 tonne au noir tonneau noir Page 178, calculation 7 17 5 7 17 6 ditto 0 11 6-1/2 0 11 9-1/2 Page 183 Fig. 170 Fig. 171 ditto Fig. 171 Fig. 170 Page 215 Elberfeldt Elberfeld Page 220, Fig. 234 d d′ as in text Page 229 see ... page 224 see ... page 223 Page 240 F′ G′ F G as in illustration Page 243 tire tiré ditto _k_ K Page 245 labiacæ labiatæ Page 249 -- quote marks added after ... for making candles. ditto undica indica Page 278 60·30 feet 69·39 feet Page 311 rhamnus fragula rhamnus frangula Page 318 _Figs._ 297, 298. _Figs._ 296, 298. Page 331 its bottom, C its bottom, _c_ Page 336 Gtakamite Atakamite Page 345, Fig. 318 -- ′s added as mentioned in text Page 356 pulley or whorl _g_ pulley or whorl _q_ as in drawing Page 372 5·463 lbs. of force 5463 lbs. of force Page 385 45 (or nearly so) 45° (or nearly so) Page 394 Münzstampeln Münzstempeln Page 403 are constantly making are constantly made Page 450 1·375 137·5 Page 464 -- Fig. 384 renamed Fig. 384*, (also reference to this illustration in text) Page 480, table header 3/4 to 174 3/4 to 1-1/4 Page 481 Hamecons Hameçons ditto Fishangeln Fischangeln Page 499 _fig._ 524 _fig._ 452 Page 510 Bernardiere Bernardière ditto cachemire cachemere as elsewhere Page 515, Peroxide 2F 2Fe of iron Page 524, formula (1) 1·000,000 1,000,000 Page 530, Fig. 480* lower d b Page 534 -- Opening quotes added before conclusion nr. 1. Page 538, schematic -- 2 inserted in second row Pillow Fustian Page 548, Fig. 482 -- reference letter s added Page 552 30,000 feet of gas 30,000 cubic feet of gas Page 553 _fig._ 488 _fig._ 489 (second reference in text) Page 554, formula 7 ) ( Page 561 we have 100·4 we have 100 and 4 Page 574, table curly bracket embraces curly bracket embraces lime and silica silica only Page 580, Fig. 507 -- illustration numbers and 508 interchanged to conform to text Page 594 (3 × 77·6) 232·8 (3 × 77·6) = 232·8 Page 608 -- closing quote mark added after ... 47 millions per annum. Page 618 Graufärbe Graufarbe Page 645 Wohler Wöhler Page 650 a section of the a section of the presser pressure Page 658 _p_, small spiral P, small spiral springs springs as in drawing Page 670 Liebeg Liebig Page 674 Elbeuf Elbœuf Page 684 Huttenberg Hüttenberg Page 709 shachtofen schachtofen Page 713 ruckstein rückstein as elsewhere Page 740 as is shown in _fig._ as is shown in _fig._ 621. 622. Page 745 Himmelsfurst Himmelsfürst ditto Beschertgluck Beschertglück Page 746 Huelgoet Huelgoët Page 747 gelena galena ditto Huelgöet Huelgoët Page 748 Kongsburg Kongsberg as elsewhere Page 749 _z_′ _z_′ _z z_ as in drawing Page 750 Z′ Z′ _z z_ as in drawing Page 752 Poulläouen Poullaouen as elsewhere Page 760 Vicenago Viconago Page 774 Rudersdorf Rüdersdorf Page 783 Farberröthe Färberröthe Page 784 Societé Société Page 785 Kuhlman Kuhlmann Page 792 silk-works are reared silk-worms are reared Page 793 magnesien magnésien Page 805, Figs. 656 -- primes added as and 657 described in text Page 814 Poullaounen Pouallouen as elsewhere Page 818 K K′ K′ K′′ as in illustration Page 822 Ehrenfriedensdorf Ehrenfriedersdorf Page 828 mlydenum molybdenum Page 829, table , · (2x) ditto -- blank line inserted under Water ditto La Ferte-sous-Jouarre La Ferté-sous-Jouarre Page 849 rothelie gende rothe liegende ditto lumachello lumachella Page 853 Breïtlingerwetter- Breitlingerwetterschacht schacht ditto _m_, _n_, _o_, _q_, _m_, _n_, _o_, _q_, R, _s_ _r_, _s_ Page 854/855 (table) -- table notes [a] through [d] were printed as vertical text in the original work Page 859 _t t_ _t_ T as in illustration Page 868 oölite oolite ditto Puzzuolo Puzzuoli Page 874 Braconot Braconnot as elsewhere Page 889 (table) 93·024. 93,024 Page 891 Stichstoffoxyd Stickstoffoxyd Page 895 Hyociamus Hyosciamus as elsewhere Page 897, table -- the original work has a mixture of plain text (olive oil and sperma- ceti) and table; this has been changed to a table Page 898 Wurtemburg Wurtemberg as elsewhere Page 900 by passing into a by passing into a slit- slit-groove the verti- groove in the vertical cal turning shaft turning shaft Page 909 rosmarinus officialis rosmarinus officinalis Page 922 _a_, _c_, _d_ _a_, _b_, _c_ Page 929 -- quote marks added after ... from the invention. Page 930, table -- 2 added before Journey- men Page 931, table, first or 4 vats 3 or 4 vats line Page 933 (p. 967.) (p. 936.) Page 944, table grams grains header above No. I Page 989, Fig. 864 lower d b Page 1000 rollers, _figs._ rollers, _figs._ 885. 886. 886. 887. Page 1001 Descotil Descotils Page 1002 Goro-Blagodatz Goroblagodat as else- where Page 1029 Mintereau Montereau as elsewhere Page 1056 Solfaterra Solfetara Page 1080 -- quote marks added after ... casualty from explosion. Page 1090 schlot-plan schlot-pan Page 1074 _fig._ 50 _fig._ 950 Page 1106 _Fig._ 796. _Fig._ 976. Page 1127 _Fig._ 1011. _Fig._ 1012. Page 1129 _Figs._ 1023. and _Figs._ 1024. and 1025. 1026. Page 1137 Himmelfürst Himmelsfürst Page 1175 -- quote marks added after ... or of the alloys. Page 1185 Liquidamber Liquidambar styraciflua styraciflua Page 1196 the feeder unites them the feeder unties them Page 1245 The portion B is to be The portion A is to be washed again washed again Page 1250, -- missing 0 in shillings- calculation column added Page 1252 Poerner Poërner Page 1253 Moiree Moirée Page 1281, table, 00·184 0·0184 column Carlsbad, row Fluoride of Calcium ditto column Seltzer, 00·185; 0·0185 row Alumina ditto Pullna Püllna Page 1284 In his way In this way Page 1332 _fig._ 1230 _fig._ 1231