Chapter 6

After the unhairing, kid skins must be fermented in a drench of bran, whose purpose is to completely decompose the remaining albuminous matter, and also to remove all traces of the lime. The operation is extremely delicate. While the gelatine is not so sensitive to the decomposing action of the ferment, nevertheless great care is required to prevent overfermentation and resulting damage to the texture of the skin. It is impossible for even the most experienced to tell just how long the fermentation should continue. Sometimes the work is done in two or three hours, and sometimes it requires as many days. Incessant watchfulness both day and night is required to detect the critical moment. With the less delicate skins this bran bath is not necessary. Lime and acid solutions accomplish the same purpose. When the gelatine matter is all removed the skins are ready for the actual curative process.

Oil dressing or Indian dressing--which merely differ in application, but are founded upon the same principle--is the most simple method of curing skins. The principle of each is the soaking of the gelatine fibers of the skin with oil, the union of the latter and the gelatine appearing in the form of oxide, and resulting in the insoluble, undecomposable, pliant, and tough material known to the commercial world as leather. The first step in the oil dressing, after the skins have been duly soaked to render them porous and absorptive, is to cover them with fish oil and place them in the stocks or fulling machines--huge wooden hammers with notched faces working in iron cases--where they are beaten and turned, and subjected to a uniform pressure until the oil is gradually absorbed. After taking them out, hanging them up, and stretching them, the oil and fulling process is repeated according to the thickness of the skin, and until every part of it is full of oil. After this the skins are dried in a mild heat that causes the oxidization of the oil. This being completed, all the superfluous oil is removed by putting the skins in an alkali bath. Then the curing process is complete.

With the preparation of kid leather alum is the astringent curative agent. Its operation is accompanied by that of others whose purpose is to secure elasticity and pliability, and mainly to preserve that beautiful texture which makes kid leather superior to all others. These assistants in the process are eggs, flour, and salt. They are combined into what is called a custard. A proper quantity of the custard and a number of skins having been put together in a dash wheel, where they are thrown about for some time, the open pores of the skin absorb the custard freely, and become swelled by the chemical union of the custard and the skin. In trade parlance this swelling is known as "plumping." This having progressed satisfactorily, the skins are folded together with the fleshy side outward, and are dried by a gentle heat.

They are now cured, but they are yet hard and rough. Another objectionable feature is that they are of unequal thickness. Breaking and staking, as they are called, are now resorted to, to make the skins soft, pliable, and of even texture, removing the superfluous chemicals with which they become charged, and the stiffness by manipulating the fibers. Much trained skill and dexterity, especially in knee and arm staking, are required in the stretching, which is the essential feature of these operations. Breaking is first resorted to. The break beam, which is armed at each end with a knife edge, oscillates up and down. In a frame beneath it the operator stretches the dried and stiff skin. The break beam comes down upon the skin, stretches and softens it, and removes much surplus custard. The operator presents a new surface to each stroke of the break beam, and in a very short space of time the entire skin is rendered soft and pliable.

Further manipulation upon the arm or knee stake--of which a dull, semicircular knife blade, supported upon a suitable standard upon the floor or upon a beam about opposite the worker's elbow is the main feature--is required. The skin must be drawn across this knife blade with a considerable application of force so as to reduce the unduly thick parts, stretch the skin and secure a uniform thickness suitable for gloves. Much dexterity, especially in the case of fine skins, is required in this operation to avoid cutting or tearing. The operator places the fleshy side of the skin over the knife, grasps the two ends of the skin, and placing his knee upon it and slowly drawing the skin across the knife edge, he brings his weight to bear upon it. If the operator is skilled and experienced the skin yields quickly, when needed, to the strain applied and a uniform texture is secured. The operation of transforming the skin into leather is now finished, but age is necessary to secure perfect pliability and softness. The skins are, therefore, laid away to let the slow chemical operation going on within them be completed.

The visitor can now watch the further processes of manufacture by visiting the dye rooms. Skins which have already been aged are immersed in dye vats, where the delicate colors are imparted to them. The same care is not required in obtaining the ordinary range of dark colors, for these are "brushed" on, the skin being spread upon a glass slab and the dye being painted on with a brush. After they are dyed the skins are sometimes somewhat hard, and in some classes have to be staked again in order to restore their pliability. The finishing touches to a kid skin are secured by rubbing the grain side over with a size, which imparts a gloss. The experience of Gloversville manufacturers with "buck" gloves has enabled them to impart a special finish to a skin which is very popular under the title of "Mocha." This is the same as suede finish, which is produced in other countries by shaving off the grain side of the skin at an early stage of its progress. The Gloversville method is much better, however, and has more perfect results. Here the grain is removed, and the velvet finish secured by buffing the surface on an emery wheel. The surface of the leather is cut away in minute particles by this process, and the result is an exceedingly even and velvety texture, superior to that obtained by other methods. European manufacturers do not approach the Americans in this respect.

The leathermaker leaves off and the glovemaker begins.

A marble slab lies before the cutter on a table, and every particle of dirt or other inequality is removed before "doling." The skin is spread, flesh side up, upon the slab, and the cutter goes over it with a broad bladed chisel or knife, shaving down inequalities and removing all the porous portions. The dexterity with which this is done makes the operation appear extremely simple, but any but a skilled and experienced operative would almost surely cut through the skin. The most delicate part of the glovemaker's art, in which exact judgment is required, comes in preparing the "tranks" or slips, from which the separate gloves are cut. The trank must be so cut as to have just enough leather to make a glove of a certain size and number. The operation would be easy enough if the material were hard and stiff, and if the elasticity were uniform, but this is rarely the case.

To accomplish this operation the trank must be firmly stretched in one direction, and while so stretched a "redell" stamps the proper dimensions in the other direction, to which the leather is trimmed. Upon the nicety with which this operation is performed depends the question of whether the finished glove will stretch evenly or too much or too little in one direction or the other. After this the trank or outline of the glove must be cut out. In olden times of glove manufacture an outline was traced upon the leather and the pattern was cut with shears. Modern invention has produced dies and presses which are universally used. The steel die has the outline of a double glove, including the opening for the thumb piece. The die rests upon the bed of the press. Several tranks are laid upon it, the lever is drawn, and in a moment the blanks are cut out clean and smooth. The gussets, facings, etc., are cut from the waste leather in the thumb opening at the same operation. Similar dies are used in the cutting of the thumb pieces and fourchettes or strips forming the sides of the fingers.

The pieces now go to the great sewing rooms of the factory, where are long rows of busy sewing girls. If the manufacturer of years ago could revisit the scenes of his earthly toil, and wander through the sewing rooms of a modern factory, he would doubtless be greatly amazed at the sight presented there. In his day such a thing was unknown. The glove was then held in position by a hand clamp, while the sewing girl pushed the needle in and out, making an overseam. All this is done now in an infinitely more rapid manner by machine, and with resulting seams that are more regular and strong than those made by the hand sewer. The overseam sewers earn large wages, and their places are much coveted. Overlapping seams are produced on the pique machine, which is a most ingenious mechanism. The essential feature of this machine is a long steel finger with a shuttle and bobbin working within, and the finger of the glove is drawn upon this steel finger, permitting the seam to be sewn through and through. The visitor to the factory can see also the minor operations of embroidering, lining--in finished gloves--sewing the facing, sewing the buttonholes, putting on the buttons, and trimming with various kinds of thread. Before the gloves are ready for the boxes one more operation remains. The gloves are somewhat unsightly as they come from the sewers' hands, and must be made trim and neat. To secure these desirable results the gloves are taken to the "laying-off" room.

In this are long tables with a long row of brass hands projecting at an acute angle. These are filled with steam and are too hot to touch. These steam tables by ingenious devices are so arranged that it is impossible to burn the glove or stiffen the leather by too much heat, a common defect in ordinary methods. The operation of the "laying-off" room is finished with surprising quickness. Before each table stands an operator, who slips a glove over each frame, draws it down to shape, and after a moment's exposure to the warmth removes it, smooth, shapely, and ready for the box. The frames upon which the gloves are drawn are long and narrow for fine gloves and short and stubby for common ones. Then the glove is taken to the stock room, where there are endless shelves and bins to testify to the chief drawback to glove making, the necessity for innumerable patterns.--_The Mercer._

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FABRIC FOR UPHOLSTERY PURPOSES.

The object of this invention is to produce a firm, solid, dust-resisting, and durable woven cloth, composed, preferably, entirely of cotton, but it may be of a cotton warp combined with a linen or other weft, and is particularly applicable for covering the seats and cushions of railway and other carriages, for upholstering purposes, for bed ticking, and for various other uses. To effect this object, a cotton warp and, preferably, a cotton weft also are employed, or a linen, worsted, or other weft may be used. Both the yarns for warp and weft may be either dull or polished, according to the appearance and finish of cloth desired. The fabric is woven in a plain loom, and the ends are drawn through say eight heald shafts, but four, sixteen, or thirty-two heald shafts might be employed. When eight heald shafts are employed, the warp is drawn as follows: The 1st warp end in the first heald shaft, the 2d warp end in the second heald shaft, and so on, the remaining six warp ends being drawn in, in consecutive order, through the remaining six heald shafts; the 9th warp end is drawn in through the first heald shaft, and so on, the drawing in of the other ends being repeated as above. The order of the shedding is as follows: 1st change. The 1st and 3d heald shafts fall, the rest remaining up. 2d change. The 5th and 7th shafts fall, and the 1st and 3d rise. 3d change. The 2d and 4th shafts fall, and the 5th and 7th rise. 4th change. The 6th and 8th shafts fall, and the 2d and 4th shafts rise. The result is that each weft thread, a, passes under six warp threads, b, and over two warp threads, in the manner illustrated by the accompanying diagram. In drawing in, when four heald shafts are employed, the 1st warp end is drawn in through the 1st heald shaft, the 2d through the 2d shaft, the 3d through the 1st, the 4th through the 2d, the 5th through the 3d, the 6th through the 4th, the 7th through the 3d, and 8th through the 4th shaft, and repeating with the 9th end through the 1st shaft. In shedding, the 1st heald shaft is lowered, then the 3d, then the 2d, and then 4th. The result, in this case, is still the same, viz., that each weft thread passes under six warp ends and over two warp ends. Although a cotton warp is spoken of in some cases, worsted or other yarn can be added to the cotton warp to obtain a variation in the pattern or design.--_Jour. of Fabrics._

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REVERSIBLE INGRAIN OR PRO-BRUSSELS CARPET.

The object of this invention is to manufacture, in a cheap fabric, a closer imitation of Brussels carpets. As is well known, an ordinary Brussels carpet is made with a pattern on one side only, but according to this invention, it is intended to produce a pattern on both sides of the ingrain or pro-Brussels carpet, so that it will be reversible. In manufacturing a reversible carpet of this class according to the present invention, the pattern is formed by means of the warp and weft combined, and any suitable ingrain warp operated by the harness or jacquard of the loom may be used. In combination with ingrain warp, a fine catching or binding warp, operated by the gear or jacquard harness of the loom, is employed, such fine catching warp being used to bind the weft into the fabric, therefore, if the fabric be woven two-ply, the ingrain warps are thrown on both the under and upper surfaces of the fabric, as well as in between the weft, according to the pattern being woven, by which means four colors are shown on both sides of the fabric, two being produced by the weft, and two by the ingrain warps. More than four colors, however, can be produced upon each side by multiplying the number of colored wefts and warps employed. If the fabric woven be a three-ply, with the addition of the ingrain warps thrown on each face of the fabric, then five or more colors would be imparted to the carpet, as any number of colors can be used to form a given pattern, by planting or arranging the colors in the warp, and the remaining colors by the wefts, and so on. The ingrain warp thread, therefore, together with the weft, used as stated above, produces an effective pattern on both sides of the carpet; consequently, it becomes reversible, and this can be accomplished whether the carpet woven be two, three, or other number of ply. By reference to the accompanying sheets of drawings, this invention will be better understood. Fig. 1 is an enlarged cross section of an improved carpet, a three-ply, that is to say, it is a carpet wherein three shuttles are employed, each carrying a differently colored weft; a represents the weft threads which may be composed of any suitable fiber, b and c are cotton or other fine warp threads, which are employed for binding the weft together, while d and e represent the ingrain or woolen warp, where it will be seen that each ingrain warp, besides lying between the weft, is thrown on both sides of the fabric, for the purpose of forming figures thereon. It will, therefore, be seen that a carpet made according to Fig. 1 will show five colors--three colors produced by the weft and two colors produced by the ingrain warp. Fig. 2 represents a carpet made with two-ply, in which case only four colors will be produced, two by the weft and two by the ingrain warp. It is, consequently, obvious that a carpet made in the manner above described will have a corresponding pattern or figure on both its sides, allowing it to be used on both sides. Fig. 3 also shows a two-ply carpet, but, in this case, six colors are produced, i.e., two colors by the weft and four by the ingrain warp, marked d, d¹, e, and e¹, the warp being so manipulated by the harness as to make the carpet reversible, and having a corresponding pattern or figure on both sides.--_Journal of Fabrics._

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ARÆO-PICNOMETER.

A modified aræometer has been recently patented by Aug. Eichhorn, in Dresden, Germany (Deutsches Reichs-Patent, No. 49,683), which will prove a great boon to chemists, distillers, physicians, etc., as it affords an easy means of determining the specific gravity of liquids, especially such of which only small quantities can be conveniently obtained.

With the ordinary aræometers, as hitherto constructed, a considerable quantity of the test fluid is required, and an elaborate calculation necessary for each determination. In the new aræo-picnometer these drawbacks are ingeniously avoided, so that the specific gravity of any liquid can be quickly and easily obtained with astonishing accuracy.

The new and important feature of this instrument consists in a glass bulb, c--see accompanying sketch--which is filled with the liquid whose gravity is to be determined. Thus, instead of floating the entire apparatus in the test fluid, only a very small quantity of the latter is required, an advantage which can hardly be overestimated, considering how difficult it is in many instances to procure the necessary supply.

^ = = = = a = = \ = / | = | |~~~~~~~~~~~~~~| | - - = - -| |- - = - | | - - = - -| |- - = - | | - / \ -| |- - | b | - | | \ / -| |- e//¯ ¯\\d | | - | c | -| |- \ _ / | | - \ / -| |- = - | | - = -| |- | | - | | - \f/ -| |- - v - | | -| / \ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

The glass bulb, c, when filled with the test fluid, is closed by means of an accurately fitting glass stopper, d, and the instrument is then placed in a glass cylinder filled with distilled water of 17.5 deg. temperature (Centigrade). The gravity is then at once shown on the divided scale in the tube, a. The lower bulb, f, contains some mercury; e is a small glass knob, which serves to maintain the balance, while b is an empty glass bulb (floater).

These instruments are admirably adapted for determining the gravity of alcohol, petroleum, benzine, and every kind of oil, also for testing beer, milk, vinegar, grape juice, lye, glycerine, urine, etc.

As the process is an exceedingly simple one and free from the drawbacks of the aræometer, we are justified in concluding that the aræo-picnometer will soon be in general use.

H. HENSOLDT, Ph.D.

Petrographical Laboratory, School of Mines, Columbia College.

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[Continued from SUPPLEMENT, No. 793, page 12669.]

GASEOUS ILLUMINANTS.[1]

[Footnote: Lectures recently delivered before the Society of Arts, London. From the _Journal_ of the Society.]

BY PROF. VIVIAN B LEWES.

IV.

Mr. Frank Livesey, in the concluding sentence of a paper read before the Southern District Association of Gas Managers and Engineers during the past month, on "A Ready Means of Enriching Coal Gas," speaking of enrichment by gasolene by the Maxim-Clarke process, said "it should, in many cases, take the place of cannel, to be replaced in its turn, probably, by a water gas carbureted to 20 or 25 candle power." And now, having fully reviewed the methods either in use or proposed for the enrichment of gas, we will pass on to this, the probable cannel of the future.

Discovered by Fontana, in 1780, and first worked by Ibbetson, in England, in 1824, water gas has added a voluminous chapter to the patent records of England, France, and America, no less than sixty patents being taken out between 1824 and 1858, in which the action of steam on incandescent carbon was the basis for the production of an inflammable gas.

Up to the latter date the attempts to make and utilize water gas all met with failure; but about this time the subject began to be taken up in America, and the principle of the regenerator, enunciated by Siemens in 1856, having been pressed into service in the water-gas generator under the name of fixing chambers or superheaters, we find water gas gradually approaching the successful development to which it has attained in the United States during the last ten years. Having now, by the aid of American skill, been brought into practical form, it is once more attempting to gain a foothold in Western Europe--the land of its birth.

When carbon is acted upon at high temperatures by steam, the first action which takes place is the decomposition of the water vapor, the hydrogen being liberated, while the oxygen unites with the carbon to form carbon dioxide:

Carbon. Water. C + 2H2O = CO2 + 4H2

And the carbon dioxide so produced interacts with more red-hot carbon, forming the lower oxide--carbon monoxide:

CO2 + C = 2CO

So that the completed reaction may be looked upon as yielding a mixture of equal volumes of hydrogen and carbon monoxide, both of them inflammable but non-luminous flames. This decomposition, however, is rarely completed, and a certain proportion of carbon dioxide is invariably to be found in the water gas, which, in practice, generally consists of a mixture of about this composition:

WATER GAS.

Hydrogen 48.31 Carbon monoxide 35.93 Carbon dioxide 4.25 Nitrogen 8.75 Methane 1.05 Sulphureted hydrogen 1.20 Oxygen 0.51 ------ 100.00

The above is an analysis of water gas made from ordinary gas coke in a Van Steenbergh generator.

The ratio of carbon monoxide and carbon dioxide present entirely depends upon the temperature of the generator, and the kind of carbonaceous matter employed. With a hard, dense anthracite coal, for instance, it is quite possible to attain a temperature at which there is practically no carbon dioxide produced, while with an ordinary form of generator and a loose fuel like coke, a large proportion of carbon dioxide is generally to be found.

The sulphureted hydrogen in the analysis quoted is, of course, due to the high amount of sulphur to be found in the gas coke, and is practically absent from water gas made with anthracite, while the nitrogen is due to the method of manufacture, the coke being, in the first instance, raised to incandescence by an air blast, which leaves the generator and pipes full of a mixture of nitrogen and carbon monoxide (producer gas), which is carried over by the first portions of water gas into the holder. The water gas so made has no photometric value, its constituents being perfectly non-luminous, and attempts to use it as an illuminant have all taken the form of incandescent burners, in which thin mantles or combs of highly refractory metallic oxides have been heated to incandescence. In carbureted water gas this gas is only used as the carrier of illuminating hydrocarbon gases, made by decomposing various grades of hydrocarbon oils into permanent gases by heat.