Imagens da página
PDF
ePub

Chinese Silver.—352 parts copper, 19.5 zhnc, 13 nickel, 2.5 silver, and 12 cobalt of iron. Hard White Metal. — Sheet brass, 32 oz. ; lead, 2 oz.; tin, 2 oz.; zinc, 1 oz. Metal for Taking Impres— sions.—Lead, 3 lbs.; tin, 2 lbs.; bismuth, 5 lbs. White Metal.—Tin, 82; lead, 18; antimony, 5; zinc, 1 ; and copper 4 parts. Metal for Tinning.—Malleable iron 1 lb., heat to whiteness; add 5 oz. regulus of antimony, and Molucca tin, 24 lbs. Frick’s German Silver.—53-39 parts copper, 17.4 nickel, 13 zinc. Best Pewter.—5 lbs. tin to 1 lb. of lead. Common Pewter.—82 parts pure tin, 18 parts lead. Speculum Metal.—Equal parts of tin and copper form a white metal as hard as steel. Less tin and a small quantity of arsenic added to the alloy forms a white hard metal of high lustre. 2 lbs. copper, 1 lb. tin, 1 oz. arsenic, form a good speculum metal. An alloy of 32 copper, 16.5 tin, 4 brass, 1:25 arsenic is hard, white, and of brilliant lustre. Type Metal.-9 parts lead to 1 antimony forms common type metal; 7 lead to 1 antimony is used for large and soft type; 6 lead and 1 antimony for large type; 5 lead and 1 antimony for middle type; 4 lead and 1 antimony for small type; and 3 lead to 1 antimony for the smallest kinds of type. Statuary Metal.-91.4 parts copper, 5.53 zinc, 1.7 tin, 1:37 lead; or copper 80, tin 20. Metal for Medals.-50 parts copper, 4 zinc. Or-Molu.-The or-molu of the brass-founder, popularly known as an imitation of red gold, is extensively used by the French workmen in metals. It is generally found in combination with grate and stove work. It is composed of a greater portion of copper and less zinc than ordinary brass, is cleaned readily by means of acid, and is burnished with facility. To give this

material the rich appearance, it is not unfrequently brightened up after “dipping” by means of a scratch brush, the action of which helps to produce a very brilliant gold-like surface. It is protected from tarnish by the application of lacquer. Spanish Tutania.-Iron or steel, 8 oz.; antimony, 16 oz.; nitre, 3 oz. Melt and harden 8 oz. tin with 1 oz. of this compound. Another Tutania.--Antimony, 4 oz.; arsenic, 1 oz.; tin, 2 lbs. Gun Metal. — Bristol 112 lbs.; zinc, 14 lbs.; tin, 7 lbs. Rivet Metal.-Copper, 32 oz.; tin, 2 oz. ; zinc, 1 oz. RiveT METAL, for Hose.—Copper, 64 lbs. ; tin, 1 lb. Bullet Metal.—98 lead to 2 arsenic. For round shot the fused metal is dropped from a high elevation in a shot tower into a basin of water; or thrown down a stack of limited height, in which a strong draught of air is produced by a blast machine. Pipe Metal for Organs.—Melt equal parts of tin and lead. This alloy is cast instead of rolled in the desired form of sheets, in order to obtain a crystallized metal, which produce a finer tone. The sheets are formed by casting the metal on a horizontal table, the thickness being regulated by the height of a rib or bridge at one end, over which the superfluous metal flows off. The sheets thus obtained are planed with a carpenter's plane, bent up, and soldered. Aluminium Bronze.—100 parts copper and 10 aluminium, measured by weighing, when combined is a durable alloy, which may be forged and worked in the same manner as copper, and is the same colour as pale gold. 80 parts copper, 19 zinc, and 1 aluminium, form a good durable alloy. Aquafortis.-Simple or Single.— Distil 2 lbs. of saltpetre and 1 lb. of copperas. Double—Saltpetre, 6 lbs., copperas, 6 lbs. in its usual crystallized state, together with 3 lbs. calcined to redness. Strong.—Copperas calcined to whiteness, and white saltpetre, of each 30 lbs.

brass, mix, and distil in an iron pot with an earthenware head. Spirit of Nitre. —White saltpetre, 6 lbs.; oil of vitriol, 14 lb.: distil into 1 * pint of water. Dilute.—Strong aquafortis, 1 oz. by measure, and water 9 oz. by measure. Proof-The same as Assayer's Acid. Compound—Double aquafortis, 16 oz.; common salt, 1 dram: distil to dryness. Aqua Regia. — Distil together 16 oz. of spirit of nitre, with 4 oz. of common salt; equal parts of nitric acid and muriatic acid mixed, or nitric acid 2 parts, and muriatic 1 part. Amber, To Work.-Amber in the rough is first split and cut rudely into the shape required by a leaden wheel worked with emery powder, or by a bow saw having a wire for the blade, Tripoli or emery powder being used with it. The roughly-formed pieces are then smoothed with a piece of whetstone and water. The polishing is effected by friction with whiting and water, and finally with a little olive oil laid on and well rubbed with a piece of flannel, until the polish is complete. In this process the amber becomes hot and highly electrical; as soon as this happens it must be laid aside to recover itself before the polishing is continued, otherwise the article will be apt to fly into pieces. Amber, To Mend.—Smear the parts which are to be united with linseed oil, hold the oiled part carefully over a small charcoal fire, a hot cinder, or a gas-light, being careful to cover up all the rest of the object loosely with paper; when the oiled parts have begun to feel the heat, so as to be sticky, pinch or press them together, and hold them so till nearly cold. Only that part where the edges are to be united must be warmed, and even that with care, lest the form or polish of the other parts should be disturbed ; the part joined generally requires a little re-polishing. Bleaching Silk.—A ley of white soap is made by boiling in water 30 lbs. of soap for every 100 lbs. of silk intended to be bleached, and in this the silk is steeped till the gum in the silk is

dissolved and separated. The silk is then put into bags of coarse cloth and boiled in a similar ley for an hour. By these processes it loses 25 per cent. of its original weight. The silk is then thoroughly washed and steeped in a hot ley composed of 13 lb. of soap, 90 gallons of water, with a small quantity of litmus and indigo diffused. After this, it is carried to the sulphuring room: 2 lbs. of sulphur are sufficient for 100 lbs. of silk. When these processes are not sufficiently successful, it is washed with clear hard water and sulphured again. Bleaching Wool.—The wool is first prepared according to the purposes for which it is intended, by treating it with solutions of soap. By this process it is cleared of a great quantity of loose impurity and grease, which is always found in wool, often losing no less than 70 per cent. of its weight. The heat of the ley must be carefully attended to, as a high temperature is found to fix the unctuous matter or yolk of the wool. After washing, it is taken to a sulphur chamber, where it is exposed to the fumes arising from the slow combustion of sulphur, for from five to twenty hours, according to circumstances. It is again washed, and then immersed in a bath composed of pure whiting and blue. It is then exposed a second time to the fumes of the sulphur, and washed with a solution of soap, which renders it of the proper whiteIless. Paper Bleaching.—For bleaching rags, and other materials from which paper is at first fabricated, rags, when grey or coloured, are to be separated and ground in the paper-mill in the usual way, till brought to a sort of uniform consistence, having been previously macerated according to their quantity and tenacity. The mass is then treated with an alkaline ley. It is next treated with a solution of chloride of lime. If this immersion do not produce the desired effect, which does not often happen if the colours are tenacious, such as red and blue, let the treatment with the alkalin: ley be repeated, and follow it

with another bath of the chlorine preparation. Then sour the whole in a bath of sulphuric acid, much diluted and cold, for when hot its action will be less effectual. Water is then to be run upon it till it comes off without colour or indication of acidity. Black is the most easily discharged colour, and will seldom require being treated with ley or steep of sulphuric acid, one bath of alkali and another of chloride of lime being sufficient to produce a good white. Old printed or written paper is first to be sorted according to its quality, and all the yellow edges cut off with a bookbinder's plane. One hundredweight of this paper is to be put sheet by sheet into vats sufficiently capacious, with 500 quarts of hot water. The whole is to be stirred for about an hour, and as much water gradually added as will rise about three inches above the paper, and to be left to macerate for four or five hours. It is then ground coarsely in the mill, and boiled in water for about an hour, taking care to add before it begins to boil, thirteen quarts of caustic alkaline ley. After boiling, it is macerated in the ley for twelve hours, when it is pressed, and, if sufficiently white, made into paper. To Bleach Prints and Printed Books. –Simple immersion in oxygenated muriatic acid, letting the article remain in it, a longer or shorter space of time, according to the strength of the liquor, will be sufficient to whiten an engraving ; if it be required to whiten the paper of a bound book, as it is necessary that all the leaves should be moistened by the acid, care must be taken to open the book well, and to make the boards rest on the edge of the vessel, in such a manner that the paper alone shall be dipped in the liquid; the leaves must be separated from each other, in order that they may be equally moistened on both sides. The liquor assumes a yellow tint, and the paper becomes white in the same proportion; at the end of two or three hours the book may be taken from the acid liquor, and plunged into pure water with the same care and precaution as recommended in

regard to the acid liquor, that the water may touch both sides of each leaf. The water must be renewed every hour, to extract the acid remaining in the paper, and to dissipate the disagreeable smell. Printed paper may also be bleached by sulphuric acid, or by alkaline or soap leys.

Bleaching Ivory. — Antique works in ivory that have become discoloured may be brought to a pure whiteness by exposing them to the sun under glasses. It is the particular property of ivory to resist the action of the sun's rays, when it is under glass; but when deprived of this protection, to become covered with a multitude of minute cracks. Many antique pieces of sculpture in ivory may be seen, which, although tolerably white, are, at the same time, defaced by numerous cracks; this defect cannot be remedied; but, in order to conceal it, the dust may be removed by brushing the work with warm water and soap, and afterwards placing it under glass. Antique works in ivory that have become discoloured, may be brushed with pumice-stone, calcined and diluted, and while yet wet placed under glasses. They should be daily exposed to the action of the sun, and be turned from time to time, that they may become equally bleached; if the brown colour be deeper on one side than the other, that side will, of course, be for the longest time exposed to the sun.

Bleaching Powder. or Chloride of Lime, is prepared by passing chlorine gas into boxes of lead in which a quantity of slaked lime is laid on shelves. The stuff to be bleached is first boiled in lime water, wash, and without drying boil again, in a solution of soda or potash; wash, and without drying steep in a weak mixture of chloride of lime and water for six hours; wash, and without drying steep for four hours in a weak solution or mixture of sulphuric acid and water; wash well and dry; upon an emergency chlorate of potash mixed with three times its weight of common salt, and diluted in water, may be used as a bieachir liquid,

To Bleach Sponge.—Soak it well in dilute muriatic acid for twelve hours. Wash well with water, to remove the lime, then immerse it in a solution of hyposulphate of soda, to which dilute muriatic acid has been added a moment before. After it is bleached sufficiently, remove it, wash again, and dry it. It may thus be bleached almost snow white. To Whiten Lace.—Lace may be restored to its original whiteness by first ironing it slightly, then folding it and sewing it into a clean linen bag, which is placed for twenty-four hours in pure olive oil. Afterwards the bag is to be boiled in a solution of soap and water for fifteen minutes, then well rinsed in lukewarm water, and finally dipped into water containing a slight proportion of starch. The lace is theu to be taken from the bag and stretched on pins to dry. Alcohol Barrels — Barrels or casks designed to be filled with alcohol, may be made tight by the application of the following solution:-Dissolve in a water bath 1 lb. of leather scraps and 1 oz. of oxalic acid, in 2 lbs. of water, and dilute gradually with 3 lbs. of warm water. Apply this solution to the inside of the barrel, where, by oxidation, it will assume a brown colour, and become insoluble in alcohol. This coat closes all the pores of the wood, and does not crack or scale off. Paste Blacking.—Mix 1 part of ivory black, 4 treacle, # sweet oil, then add + oil of vitriol and # hydrochloric acid. Dilute each ingredient with three times its weight of water before mixing. Liquid Blacking.—2 lbs. of ivory black in fine powder, treacle 14 lb., + pint of sperm oil. Rub the black and oil well together, add the treacle and mix. Another Method. 4 oz. of ivory black, 3 oz. coarse sugar, a table-spoonful of sweet oil, and 1 pint of weak beer; mix them gradually together until cold. Black Reviver.—Take 2 pints of vinegar, and infuse 1 oz. of iron filings, 1 oz. copperas, 1 oz. ground logwood,

[ocr errors]

Blue Black is a paste made of ivory black and indigo, ground together with water. Blue, Soluble.—7 parts oil of vitriol, place in a glass vessel, and set this in cold water, add gradually 1 part indigo in powder, stirring the mixture at each addition with a glass rod. Cover the vessel for twenty-four hours, then dilute with an equal quantity of water. Boiler Incrustation.—The following remedies have been used with varying success to prevent incrustation:1. Potatoes, oth of weignt of water prevents adherence of scale. 2. 12 parts salt, 2} caustic soda, 4 extract of oak bark, 3 potash. 3. Pieces of oak-wood suspended in boiler and renewed monthly. 4. 2 oz. muriate of ammonia in boiler twice a week. 5. A coating 3 parts of black-lead, 18 tallow, applied hot to the inside of the boiler every few weeks. 6. 124 lbs. of molasses fed into an 8-horse boiler at intervals, prevented incrustation for six months. 7. Mahogany or oak sawdustin small quantities. Use this with caution, as the tannic acid attracts iron. 8. Carbonate of soda. 9. Slippery elm bark. 10. Chloride of tin. 11. Spent tanners’ bark. 12. Frequent blowing off. Brightening and Colouring Brass.-The work to be brightened and coloured is first annealed in a redhot muffle, or over an open fire, allowing the cooling to extend over one hour; the object of the heating being to remove the grease or dirt that may have accumulated during the process of fitting. Soft soldered work, however, must be annealed before fitted together, and afterwards boiled in a lye of potash; this is also done with work having ornamental surfaces. Next, it is immersed in a bath of diluted oil of vitriol or aquafortis, which may be made with two or three parts of water, and one of acid; but the old acid that contains a small quantity of copper, in solution, is frequently preferred. The work is allowed to remain in this liquid for one or two hours, according to the strength of the acid; it is then well rinsed in water, and scoured with sand, which is applied with an ordinary scrubbing brush, and washed. The pickling bath is made by dissolving one part of zinc in three parts of nitric acid of 36° Baume, in a porcelain vessel, and adding a mixture of eight parts of nitric acid, and eight parts of oil of vitriol. Heat is then applied, and when the liquid is boiling the work is plunged into it for half a minute, or until the violent development of nitrous vapour ceases, and the surface is getting uniform. Then it is plunged into clean water, and well rinsed, to remove the acid. The ordimary, dark greyish, yellow tint, which is thus very often produced, is removed on immersing the work again in aquafortis for a very short time. Then it is plunged into clean or slightly alkaline water, well rinsed to remove the acid, and plunged into warm dry beech or boxwood saw-dust, and rubbed until quite dry. To prevent the action of the atmosphere it is lacquered; if a green tint is to be produced, the lacquer is coloured with turmeric. A dark, greyish, but agreeable tint, is obtained by immersing the work previously in a solution of white arsenic in hydrochloric acid, or in a solution of bichloride of platinum, under addition of some vinegar, or rubbing with plumbago. Bronze for Statuary.—1. Copper, 88 parts; tin, 9 parts; zinc, 2 parts; lead, 1 part. 2. Copper, 88% parts; tin, 5 parts; zinc, 10% parts; lead, 2 parts. 3. Copper, 90 parts; tin, 9 parts; lead, 1 part. 4. Copper, 91 parts; tin, 9 parts. For Medals.-1. Copper, 89 parts; tin, 8 parts; zinc, 3 parts. 2. Copper, 95 parts; tin, 5 parts. For Cutting Instruments.-Copper, 100 parts; tin, 14 parts. For Ornaments.-1. Copper, 82 parts; tin, 3 parts; zinc, 18 parts; and lead, 2 parts. 2. Copper, 83 parts; zinc, 17 parts; tin, 1 part; lead, 4 part. Bronze Liquid.—Take 1 pint of

[ocr errors]

strong vinegar, 1 oz. of sal ammoniac, # oz. of alum, 4 oz. of arsenic; dissolve them in the vinegar, and the compound is fit for use. We know brass-founders who have been in the habit of using this for several years, and, where the metal is good, it is seldom found to fail. Bronze Powders, Aurum Mustvum.—Melt together, in a crucible over a clear fire, equal parts of sulphur and the white oxide of tin. Keep them continually stirred with the stem of an earthenware pipe or glass rod, till they assume the appearance of a yellow flaky powder. An iron rod must not be used in stirring up any mixture of sulphur when melted, or the sulphur and iron will unite. Aurum Musivum, or Mosaic Gold, is used as a cheap bronze powder. It is rubbed on with the finger. Another way to prepare it is to take quicksilver, tin, sulphur, and sal ammoniac, equal parts. First melt the tin, then pour the quicksilver into it, afterwards grind up with the amalgam thus made the sulphur and sal ammoniac. Place the mixture in a crucible, and heat until the powder in the crucible becomes goldcoloured, and also until no fumes of quicksilver arise. Copper-coloured Bronze may be obtained by dissolving copper in aquafortis until it is saturated, and then putting into the solution some small pieces of iron, when the copper will be precipitated in the metallic state; the fluid must then be poured off, and the powder carefully washed, dried, and levigated, when it may be put by for use. Bronze powder is sometimes made from Dutch gold, which is sold in books at a very low price. All these inferior bronzes require to be covered with a coat of clear varnish, or they will very soon lose their metallic appearance, nor will the varnish entirely prevent, although it will greatly retard, this change. Cheap Bronze.—Verdigris, 8 oz. ; flowers of zinc or tutti powder, 4 oz.; borax and nitre, of each 2 oz.; corrosive sublimate, 2 drachms, made into a pasto G

« AnteriorContinuar »