Part 80
=BRASS-STAIN.= _Prep._ 1. Sheet-brass (cut into small pieces) is exposed to a strong heat for 2 or 3 days, then powdered, and again further exposed in a like manner for several days; the whole is then reduced to fine powder, and exposed, a third time, to heat, testing it occasionally, to see if it be sufficiently burnt. When a little of it, fused with glass, makes the latter swell and froth up, the process is complete. It imparts to glass a green tint, passing into turquoise.
2. Equal parts of plate-brass and sulphur are stratified together in a crucible, and calcined, until they become friable; the whole is then reduced to powder, and exposed to heat as before. This imparts a calcedony red or yellow tinge to glass by fusion; the precise shade of colour being modified by the mode of using it.
_Obs._ The common practice in the glass-houses is to conduct the calcination by exposing the metal, placed on tiles, in the leer or annealing arch of the furnace; a plan both convenient and economical.
=BRASS'-WORK.= Articles of brass and copper, when not varnished or lacquered, may be cleaned and polished with sweet oil and tripoli, rotten-stone, or powdered bath-brick, applied with friction on flannel, and 'finished off' with leather; due care being taken to ensure the absence of anything gritty, which would scratch and disfigure the surface of the metal. A strong solution of oxalic acid in water gives brass a fine colour. Vitriol and spirits of salts make brass and copper very bright, but the polish thus obtained soon tarnishes, and the articles consequently require more frequent cleaning. A strong lye of roche alum and water also improves the appearance of brass. In all cases where acids or saline matter has been used, the metal should be at once well rinsed in clean water, and then wiped dry, and finally dry polished with soft leather.
BRASS INLAID-WORK may be cleaned with tripoli and linseed oil, applied by a rubber of felt or leather; the whole being afterwards thoroughly rubbed off, and then finished with clean soft leather. The ornaments of a French clock, and similar articles, are said to be best cleaned with bread-crumb, carefully rubbed, so as not to injure the wood-work. ORMOLU CANDLESTICKS, LAMPS, and BRANCHES, may be cleaned with soap and water. LACQUERED and GILDED ARTICLES are spoiled by frequent rubbing, and by acids and alkaline leys.
1. A fine colour may be given to BRASS ORNAMENTS, when not gilt or lacquered, with a little sal-ammoniac, in fine powder, moistened with soft water. The articles must be afterwards rubbed dry with bran and whiting. Another plan is to wash the brass-work with a strong lye of roche alum (1 oz. to water 1 pint), and after rinsing it in clean water and drying it, to finish it off with fine tripoli. These processes give to brass the brilliancy of gold. See BRASS-PASTE.
2. A gold varnish for giving a beautiful gilding to brass and bronze objects is prepared from 16 grams of shell-lac, 4 grams of dragon's blood, 1 gram of turmeric-root, and 332 grams of rectified spirit of wine. The varnish is thinly stroked over the surface with a sponge, the metal being warmed over a small coal fire.
The surface at first appears dull, but soon after it appears as if most beautifully gilded. The ready-prepared spirituous varnish must be preserved in well-stoppered vessels.--_Dingler's Journal._
=BRASS'ING.= _Syn._ BRASS-COATING. 1. Copper-plates and copper-rods may be covered with a superficial coating of brass by simply exposing them, in a heated state, to the fumes given off by melted zinc at a high temperature. The coated plates and rods are rolled into thin sheets or drawn into wire. The spurious gold wire of Lyons is said to be made in this way.
2. Vessels of copper may be coated with brass, internally, by filling them with water strongly soured with hydrochloric acid, adding some amalgam of zinc and cream of tartar, and then boiling the whole for a short time. This plan may be usefully applied in certain cases to copper boilers in laboratories, and to other purposes.
3. By the electrotype (which _see_).
=BRAUNETINCTUR--QUINSY OR BROWN TINCTURE= (Netsch, Rauschau), an embrocation for the larynx, is a mixture of 3 parts oil of cloves and 1 part creosote. (Hager.) According to Leimbach 1 part creosote with 3 parts of a spirituous tincture of cochineal perfumed with oil of cloves.
=BRAWN.= A boar or its flesh. When young, the horny parts feel moderately tender. If the rind is hard, it is old. (Mrs Rundell.) Also in cookery, the flesh of the boar, or of swine, collared so as to squeeze out as much of the fat as possible, boiled, and pickled.
=Brawn, Mock.= _Prep._ (Mrs Rundell.) Take the head and belly-piece of a young porker, well saltpetred; split the head and boil it; take out the bones and cut it to pieces; then take 4 ox-feet, boiled tender, and cut them in thin pieces; lay them in the belly-piece with the head cut small; roll it up tight with sheet tin, and boil it 4 or 5 hours. When it comes out set it up on one end, put a trencher on it (within the tin), press it down with a heavy weight, and let it stand all night. The next morning take it out of the tin and bind it with a fillet, put it in cold salt-and-water, and it will be fit for use; it will keep a long time, if fresh salt-and-water are put into it about once every four days.
=BRAXY.= Inflammation of the bowels in sheep, chiefly affecting young sheep. It is most frequent during winter, and occurs in exposed wet localities. The symptoms are restlessness, thirst, tenderness along the spine or belly, and constipation.
_Treatment._ Bleed early, and give 3 _oz._ castor oil; 8 grains of calomel; 1/2 _oz._ of laudanum; 3 _oz._ treacle; beat up with two eggs, and mixed with about 6 _oz._ of warm water; let this be repeated in half doses every six hours.
This should be combined with clysters and hot fomentations to the belly. If, after two days, no benefit should be derived, give thrice daily, 5 grains of calomel, 20 grains of carbonate of ammonia, and 1-1/2 dram of laudanum, in gruel. The animal should be removed to a shed or sheltered place.
=BRAZIL NUTS.= The particular tree yielding these nuts (the _Bartholetia excelsa_) is a native of Brazil, whence the nuts are exported to the yearly annual amount of about 60,000 bushels.
When the kernels of the nuts are submitted to pressure they yield an oil in great repute for domestic purposes and for export, each pound of the nuts yielding nine ounces of the oil, valued at two shillings the pound. According to Martius, this oil consists of 74 per cent. of eldein, and 26 per cent. of stearin. The finely laminated inner bark of the trunks is also a valuable article of commerce, especially adapted for the caulking of ships and barges, and is worth about eighteen shillings the cwt.
The following analysis by Corenwinder gives the composition of the kernels taken from the nuts when in a fresh condition:
Water 8·00 Oil 65·60 Nitrogenous matters 15·31 Non-nitrogenous organic matters 7·39 Phosphoric acid 1·35 } Lime, potash, silica, &c. 2·35 } 3·70 ------ 100·00
=BRAZIL'-WOOD= (-z[=e]le'-). _Syn._ BRAZIL[double-dagger]; LIG'NUM BRAZILIEN'SE, L.; BOIS DE BRÉSIL, Fr. A dye-stuff furnished by several species of trees of the genus _cæsalpin'ia_, and much used in dyeing various shades of red. The usual practice is to boil it for some hours in hard spring-water, and to keep the resulting decoction for some time, or until it undergoes a species of fermentation; as it is thus found to yield more permanent and beautiful colours than when employed fresh. The following are examples of its application:--
_a._ For COTTON:--
1. The goods are first boiled in a bath of sumach, next worked through a weak mordant of solution of tin, and then run through the Brazil bath lukewarm. This gives a bright red.
2. The goods are alumed, rinsed, next mordanted with solution of tin, rinsed again, and then turned through the Brazil dye bath. This gives a rose colour.
_b._ For LINEN:--This, for the most part, is similar to that adopted for cotton.
_c._ For SILK:--The goods, after being alumed in the same way as wool, but at a lower temperature, are rinsed, and passed through the Brazil-wood bath lukewarm.
_d._ For WOOL:--The goods are first steeped or boiled in a weak mordant of alum and tartar, for 1 hour, and then allowed to lie in the cold liquor for 2 or 3 days, with frequent moving about; they are lastly boiled in the Brazil-wood bath for about 1/2 an hour.
_Obs._ The shades of colour given with Brazil-wood may be modified by varying the strength of the bath, the mordant, &c. The addition of a little alum turns it on the purple. A little alkali added to the bath, or passing the goods, after being dyed, through water holding a little alkali in solution, produces what is called false crimson. A deep crimson is obtained by adding a little logwood to the Brazil-wood bath. 1 lb. of Brazil-wood, 1/2 oz. of alum, and 2 oz. of tartar, are sufficient to dye from 20 to 28 lbs. of cotton, according to the depth of shade required. See DYEING, RED DYES, &c.
=BRAZI'LIN.= _Syn._ BREZE''L[)I]NE, SAPAN'[)I]NE. The colouring matter of Brazil-wood. It forms small orange-coloured needles, soluble in both water and alcohol. Alkalies turn it violet; acids, yellow. Bolly has shown it to be identical with the colouring matter of Sapan-wood.
=BRA''ZING.= The operation of uniting pieces of copper, brass, iron, &c., by means of hard solder.
_Proc._ The edges, after being filed or scraped quite clean, are covered with a mixture of hard solder and powdered borax, made into a paste with water. The whole is then allowed to dry, and is afterwards exposed, in a clear fire, to a heat sufficient to melt the solder. See AUTOGENOUS, SOLDERING, SOLDERS, &c.
=BREAD= (br[)e]d). _Syn._ PA'NIS, L.; PAIN, Fr.; BROD, Ger.; BROOD, Dut.; BRÖD, Dan., Swed.; BREOD, Sax. Loaves or cakes made from ground corn, and constituting the staple article of food of all civilised nations.
This important article of food is made of the flour of different cereal grains, but only those that contain gluten admit of conversion into light or spongy bread. In this respect wheat-flour is superior to all others. When this flour is made into a paste or dough with water, and the dough, previous to baking, is left for some time in a moderately warm place, a state of fermentation comes on, owing to the sugar of the flour gradually undergoing the process of conversion into alcohol, in every respect similar to that which takes place during the fermentation of wine and beer. In this process a large quantity of carbonic acid gas is liberated, and the toughness of the dough preventing its escape, the whole mass becomes puffed up and spongy, and a light porous paste is formed, the porosity of which is still further increased by the heat of the oven. The natural process of fermenting the dough just described is, however, tedious and uncertain, whilst the dough has a tendency to run into the acetous fermentation, and to acquire a sour and disagreeable taste, by which it is rendered less nutritious and less easy of digestion. This has led to the use of a ferment which produces a similar condition more speedily, and with greater certainty. Leaven or dough was originally employed for this purpose, and the bread so made was hence called LEAVENED BREAD. At the present time barm or yeast is almost universally used for this purpose. All that is essential to make a loaf of bread is to add a proper quantity of yeast to the dough, and to allow it to remain for a short time in a warm place, and as soon as it rises or becomes spongy, to subject it to the process of baking.
In preparing his dough, the modern baker takes a part of the water needed for the batch, and having rendered it tepid or lukewarm (80° to 90° Fahr.) by the addition of boiling water, dissolves his salt in it, and adds the yeast, together with a portion of the flour. With these he forms a thin dough, which he sets aside in a moderately warm place provided for the purpose, and technically called the 'kneading trough,' 'prover,' or 'tryer,' where it soon begins to ferment and swell up. This process is called 'setting the sponge,' and according to the proportion the water in it bears to the whole quantity that is to be used, it receives the name of 'whole,' 'half,' or 'quarter sponge.' Here the sponge heaves and swells, and ultimately the surface bursts and subsides, and if not checked swells again and again in a similar manner and would continue to do so until the whole of the 'saccharine matter' was destroyed, and the dough had become sour. The baker is careful, however, to stop it before it has communicated a sourness to the mass. After the first, or, at the furthest, after the second or third 'dropping of the sponge,' he adds the remaining quantity of flour, water, and salt, necessary to form the 'batch,' and then kneads the whole until it becomes sufficiently tough and elastic to bear the pressure of the hand without adhering to it. The 'dough' is now left to itself for a few hours, during which the fermentation still goes on. The inflated mass is then again kneaded, cut into pieces, weighed, and shaped into loaves. In an hour or two these unbaked loaves swell up to nearly double their former size, and are then placed in the oven and baked. During this operation they continue for a time to increase in size, in consequence of the dilation of the pent-up gas by the heat. At length the fermentation is checked, and the dough becomes too solid to admit of further alteration.
Such are the principles and practice of the art of baking. The operations are precisely the same on both the small and the large scale, and therefore need not be separately described.
The kneading of the dough by hand is not only a very laborious process, but it is unhealthy and additionally objectionable on account of its being uncleanly. Added to this, the uniform quality of the dough is not to be depended upon. Although it is impossible to perform by machinery any labour which absolutely requires the touch of the human hand, bread-kneading machines have been introduced wherever the making of only one and the same kind of bread is required. Amongst the numerous kinds of machines devised for bread-making, is Clayton's. (_See cut._)
The constituents of the dough are placed in the cylinder, _A_, mounted in the framework, _b b_, and provided with hollow axles, _c_ and _d_, turning in their bearings at _e_. The interior of the cylinder is fitted with the framework, _f_, which may be made to revolve by the aid of the axles, _g_ and _h_. The two halves of this framework are connected together by the diagonal knives _i_, _i_, which, when the machinery revolves, work up the dough; the trough or outer cylinder revolves in the opposite direction to the revolution of the framework. The crank, _o_, is connected with the axle of the trough or outer cylinder, the crank, _p_, with that of the inner framework; as the two cranks are turned in opposite directions, they impart opposite movements to trough and framework. The revolving of the machinery may be performed by one man by the aid of one crank, since the axle, _h_, of the crank, _o_, which is fitted to the inner frame by means of the hollow axle-tree, and revolves along with it, carries a conically shaped wheel, _m_, fitted to the wheel _k_, which, being connected with _l_, causes the trough also to revolve; when therefore the wheel _m_ turns towards the right, the wheel _t_ will revolve towards the left. Another kneading machine is that of Mr Stevens. It is employed at the Holborn Union, where more than 5000 _lbs._ of bread are made every week by one man and two boys.
_Adult._ The adulteration of both flour and bread is carried to a fearful extent, more especially in London. The baker's flour is very often made of the worst kinds of damaged foreign wheat; and other cereal grains, and particularly beans, are mixed with them in grinding them into flour. In this capital no fewer than six distinct kinds of wheaten flour are brought into the market--fine flour, seconds, middlings, fine middlings, coarse middlings, and twenty-penny flour.
Among the principal substances which have been proved to have been used to adulterate wheat-flour and bread are the following:--
**Alum. *Ammonia (Sesquicarbonate). **Beans. *Bone dust. *Chalk. Clay. Copper (Sulphate). Lime (Sulphate from the soda water makers). *Magnesia (Carbonate). *Plaster of Paris. *Potash (Carbonate and bicarbonate). **Potatoes. **Rice. **Soda (Carbonate and sesquicarbonate). *Starch (Potato). **Water (in excess). Zinc (Sulphate).
Of these substances, those marked thus (*) are very frequently used; and those marked thus (**) almost universally so.
In the absence of chemical analysis the unalumed loaf may be roughly distinguished from the alumed one by the following characteristics: it is neither so white, so bulky, nor so symmetrical; it bites shorter, and it is free from the sour taste which accompanies the presence of alum. Again, unalumed bread a day or two old will be found to crumble with great readiness; alumed bread, however old, crumbles, on the contrary, with difficulty.
According to Mr Accum, the smallest quantity of alum that can be employed with effect to produce white, light, and porous bread, from the inferior kinds of flour commonly used by the bakers, is from 3 to 4 oz. to a sack of flour weighing 280 lbs. But Dr P. Markham states that the ordinary bread of the London baker is made of one sack or 5 bushels of flour; 8 oz. of alum; 4 lbs. of salt; 1/2 gall. of yeast; and about 3 galls. of water. Our own analyses, extending to many hundred samples of London bread, as well as those of other chemists, show that even this large quantity of alum is often very much exceeded by the bakers.
Alkaline substances, as the carbonates of ammonia, soda, and potash, are often employed to realise the important consideration of producing light and porous bread from spoiled, or, as it is technically called, sour flour. The first salt becomes temporarily converted into a gaseous state during the operation of baking, causing the dough to swell up in minute bubbles, which thus render it light and porous; the salt itself being at the same time, for the most part, volatilised. Alum is added, not only with a like intention, but also to enable the dough to carry more water. There are several instances of convictions on record of millers and bakers having used gypsum, chalk, and pipeclay in the manufacture of their goods. A gentleman lately writing from the North of England says that he found in one sample of flour which he recently examined upwards of 16% of gypsum; and in another, 12% of the same earth.
A few years since it was discovered that some of the bakers in France and Belgium added blue vitriol to their dough to make it take more water, in the same way as the English baker uses alum. 1 oz. of this sulphate was dissolved in a quart of water, and a wine-glassful of this solution added to the water necessary to make about 50 4-lb. loaves. This enormous crime was soon detected, and deservedly caused the ruin of its heartless perpetrators.
_Exam._ The following are the methods employed for the discovery of the principal sophisticants of bread, and as the chief of these, and the one most difficult of identification is alum, we have given prominence to the processes now generally adopted for the detection of this article:--
1. ALUM:--_a._ (Robine and Parisot.) About 1/4 lb. of the suspected bread (somewhat stale or dry) is reduced to crumbs, macerated for 2 or 3 hours in cold water, and then squeezed through a clean piece of white linen. The liquid is next evaporated to dryness at a steam-heat, the residuum redissolved in a little hot water, and the solution filtered. Liquor of ammonia or a solution of sal-ammoniac, and a solution of chloride of barium added to the filtered liquid, give a white precipitate when ALUM is present.
When nearly the whole of the alum has suffered decomposition in the loaf, as is frequently the case, the following process is required:--
_b._ (M. Kuhlman.) 4 or 5 oz. of bread are reduced to ash, which is powdered and treated with nitric acid, the mixture evaporated to dryness, and about 1 oz. of hot water added. A little caustic potassa is added to the last solution (unfiltered), the whole boiled a few minutes, and passed through a filter. The filtrate is next tested with a solution of sal-ammoniac, and the whole again boiled for 2 or 3 minutes. If a precipitate forms it is alumina; every 50 gr. of which are equivalent to 332 gr. of crystallised alum.
_c._ The suspected sample is wetted with a weak solution of logwood, or, preferably, of cochineal. Pure bread is only slightly stained by this solution; bread containing alum strikes a lavender, lilac, or purple colour, according to the quantity of the adulterant present. If it acquires a pearl-grey or bluish tint, some alkali (potash, soda, or ammonia) is present.
_d._ (J. A. Wanklyn.) 100 grams of bread are incinerated in a platinum dish, capable of holding the whole quantity at once. The incineration is managed at a comparatively low temperature, and takes some four or five hours; the platinum dish being heated by means of a large Bunsen burner, abundantly supplied with air. It is well to continue the ignition until the bread-ash is nearly completely burnt, and it is advisable to weigh the dish containing the ash. The weight of the ash should not sensibly exceed 2 grams. The ash having been obtained is then moistened with 3 c. c. of pure strong hydrochloric acid, and then some 20 to 30 c. c. of distilled water is added, and the whole is boiled, filtered, and the precipitate washed several times with boiling water. In this manner a precipitate consisting of a silica, together with some unburnt carbon, is left on the filter, whilst the filtrate contains the phosphates. The precipitate, which, after being burnt, consists of silica, is weighed. The filtrate is mixed with 5 c. c. of ammonia (sp. gr. 0·880), whereby it is rendered powerfully alkaline and opaque, owing to the precipitation of the phosphates. It is finally mixed gradually with some 20 c. c. of strong acetic acid, and as the acid is being poured in, it is to be observed that the liquid is alkaline and opaque, until some 5 c. c. of the acid have been added; that when about 10 c. c. have been added the liquid is acid and much clearer, and that at least 10 c. c. of strong acetic acid are added after the establishment of a distinctly acid reaction. The liquid is then boiled and filtered, and the precipitates, consisting of phosphates of alumina and iron, well-washed with boiling water, ignited and weighed. The last step is the determination of the iron in the weighed precipitate, and this is accomplished either by reduction and titration with standard solution of permanganate in the well known manner, or else by a colour process, viz., by trituration with ferrocyanide of potassium. Having ascertained the amount of iron in the precipitate of mixed phosphates, it is only necessary to calculate it into phosphate of iron, and to subtract the weight of phosphate of iron from the total weight of the mixed phosphates, and the difference is the phosphate of alum yielded by 100 grams of the bread. The following results have been obtained by applying the above-described process to samples of bread presumed to be free from alum:--
_From 100 grams of Bread._