One of the principal uses of hone is the manufacture of knife handles, toothbrushes, babie,s' gum rings, and a great variety of such small articles of turnery. Almost the only kinds of bone employed for this purpose are the shin and buttock bones of oxen and calves. They are first boiled, as described above, to remove the fat, and this process robs them, at the same time, of some of their bone cartilage, thus rendering them rather more brittle. Next they are bleached, by laying them in the sun, or by other means, and are sawn and turned into shape as required. When finished, they are soaked in turpentine for one day, boiled in water for about an hour, and then polished, first with glass paper, second with rrent sand or Flanders brick on a wet flannel, third with whiting on a damp woollen rag. Finally, a small qufintity of wax is rubbed on quickly with the object of filling up the tiny pores of the bone, but very little must be allowed to remain on the article. Common articles, such as cheap tooth and nail brushes, are often polished, by simply using a little slaked lime on a damp flannel or woollen rag. An excellent method of cleaning bones is to soak them for twenty-four hours in a solution of 1 lb. soda ash and lb. calcined lime in three quarts of hot water, then wash them thoroughly and put them to bleach. Bone shavings, scrapings, and sawdust are in considerable request among pastrycooks and others, for making jelly.
In some bone-producing countries, notably South America, whence enormous quantities of bones are imported to this country and a few Continental ports, the bones are commonly calcined in the open air before shipment, an operation which greatly reduces their bulk, by eliminating all the moisture they contain, and rendering them a friable mass. In this form, they are known as " bone ash," and are consumed chiefly in the manufacture of high-class artificial Manures (which see), while abOut 4500 tons per annum are employed in the china manufactories of this country. Less irnportant applications of the substance are for the making of cupels used in assaying, and for case hardening small articles of steel.
Another product derived from bones is "sal-ammoniac '' or " chloride of ammonia." This is produced by subjecting bones, which have previously been boiled to remove the fat, to a process of distillation in large retorts, by which is drawn off a vapour composed of carbonic acid, various hydrogen-carbon compounds, water (steam) holding carbonate of ammonia in solution, and a peculiar oil which is collected separately and afterwards burnt in specially constructed lamps for the purpose of depositing "lamp-black." Towards the conclusion of the distillation process, chloride of ammonia and sulphate of soda are formed; the former is separated by sublimation, and the latter is dissolved in water and crystallized. Tbe mass left in the retorts represents the earthy portions of the bone, blackened by the carbon of the organic matter and known as " Ivory-black," "Bone black," or " Animal charcoal" (which see). By exposing this last to an open fire, the carbon is consumed, and the bones are rendered almost white. They are then reduced to powder (bone-ash), and are used for cupel making, as a polishing powder for plate, &c., and by the phosphorus-match makers.
The purification of ammonia salts from the waste of bone-gas and animal-charcoal works is rendered difficult by the presence of empyreumatic organic matters (Dippele's oil). The cost
is much increased by the necessity for re-subliming the crude products, while the neutralization of the condensation waters with hydrochloric acid creates a nuisance, by reason of the ammonia sulphide and cyanide present. IVIr. J. V. Divis has elaborated a mode of purification, which he thinks may be used even in sugar-works making their own animal charcoal, 8 to 10 per cent. (according to the quality of the bones) of ammonia water being obtainable, containing 7 to 9 per cent. of actual ammonia, the yield of bone oil being 1-7 to 2 per cent. The ammonia waters are collected in old petroleum barrels and allowed to stand two days, when the floating oil is skimmed off. The waters are then gently heated and just neutralized with hydrochloric acid, after being mixed with concentrated solution of chloride of lime, to decompose the carbonate of ammonia, without which there would be a liberation of gas. Carbonate of lime is abundantly deposited, and its precipitation clarifies the liquor. After some hours, the clear liquid is decanted, and the sediment remaining forms a good manure. The chloride of lime must be slightly deficient—never in excess. The clear but yellowish decanted solution is heated to boiling in sheet-iron tanks, which causes the rest of the impurities to separate out, and admits of _their being skimmed off. The boiling liquid is then filtered through a mixture of wood charcoal, animal charcoal, and coke, in a double-bottomed cask. Finally, it i8 evaporated in shallow pans, the vapours arising being forced through the ash-grates of the furnaces. The sal-ammoniac thus produced contains 95-3 per cent. of true chloride of ammonia and 4.2 per cent. of water.
Before detailing the important part played by bones in the manufacture of gelatinous substances, such as gelatine, size, &c., it will be necessary to refer for a moment to their composition. After undergoing the preliminary fat-extracting operation, there remain the two essential constituents— cartilage and lime-earths. And here it might be well to remark that the fat is not really a constittent of bone, but an accessory, for varieties of bone exist identical in other respects, but quite free from grease. A portion of the cartilage is sure to be dissolved out of the bones while they are being boiled to removed the fat, and in the large dyeing works at Manchester and other places, this is often utilized for making " size." After removing the fat, the bone liquor is boiled down in another vessel till it is strong enough for stiffening the heavy goods to which it is applied. When the size-liquor is too weak for further use, it still possesses a value as a fertilizer, and the exhausted bones are also bought up by the farmers and manure makers for a similar purpose. A modification of this plan consists in crushing the bones, treating them with steam at high pressure, and adding to the semi-gelatinous mass thus formed, a proportion of hydrochloric acid (2 per cent.) and reboiling. The fat then separates and floats on the liquor, to be easily collected and purified, by-being treated first with boiling water and a very small quantity of caustic soda, and next with animal charcoal, and finally filtered.