BONES. (Fn., Os; GER., Bein, Knochen.) Bone consists of a dense cellular tissue of membranous matter known as perzosteum, rendered hard and stiff by incorporation with certain insoluble earthy salts, of which phosphate of lime is the most important. Bones form the solid framework or skeleton of the bodies of animals, enclosing and protecting the most vital parts from external injury, and themselves clothed with softer parts called flesh. They differ greatly in form and character, some being hollow and filled with marrow, while others are solid and contain no marrow. In composition, they exhibit equally wide diversity, especially with regard to the proportions of the two principal constituents, viz. the organic (osseous cartilage or °nein) and the inorganic (earthy salts). The former, through which the nerves and blood-vessels find their way into the bone, is antecedent in growth to the latter, and is composed of modified gelatine. The earthy portion consists essentially of phosphate of lime, with carbonate of lime and small proportions of some other salts ; it is built up slowly and gradually duriug the whole lifetime of the animal, so that from the relative earthiness of the bone, some idea may be formed of the age of the animal. Oci an average, it may be said that the weight of green bones is about equally divided between the organio and inorganic components, or, when dry, about 30 to 40 per cent. of the former to 60 to 70 per cent. of tbe latter. It has been observed that bird bones are more earthy than animal bones, and contain a greater percentage of carbonate of lime in proportion to the phosphate of lime. The bones of amphibia, again, are less earthy than those of mammalia ; in fish bones, the inorganic ingredients vary between 21 and 57 per cent. The composition of fossil bones depends, in a great measure, on the conditions under which they have been preserved, and much irregularity is to be expected. Sometimes the organic matter is abundant, as in fish bones; in other cases, it is altogether wanting. Carbonate of lime is usually more strongly developed, which may he owing to the phosphate being in some deg,ree converted by the infiltration of carbonic acid or its salts.
The economic uses of bones are manifold and important. In the first place, they contain a large amount of nutritious food, which may be extracted by continued boiling in water, or by " digesting."
In treeless countries, such as Iceland, Tartary, and tbe Pampas of South America, they are commonly used as fuel ; and among many savage tribes, they forna the points of arrows and other weapons of war or the chase. But these are rather domestin than industrial applications.
Whether coming from the slaughter-houso or battle-field in a raw state, or from the domestic kitchen after having undergone one or more cookings, hones always contain an amount of fat, which must be extracted as a preliminary to any other process needed to fit them for their various uses. The elimination of the grease is usually effected by subjecting the bones to gentle ebullition, for about twenty-four hours, in water in large open coppers, and skimming off the fat as it floats. All kinds of bones should not be boiled indiscriminately together, both because the bones themselves will be devoted to different purposes, and because the quality of fat produced will likewise be various. The hollow bullocks' shank-bones are generally boiled alone, yielding the primest fat, which is sold to the soap-makers, and to tho manufacturers of " butterine '' and other curious compounds with which science provides our breakfast tables, at about 35s. to 45s. per cwt. Ordinary butchers' bones are chopped into pieces about the size of the sticks composing the bundles of London firewood, and in such a manner with regard to grain, &c., as will best expose the fat-impregnated cells of the bone to the dissolving action of the hot water. The grease from these is less in quacitity and inferior in quality to the last named, and sells at 25s. to 35s. per cwt., the price varying with the more or less brown colour. Common house-bones yield still less fat, whose general character and price do not differ materially from those just mentioned. Horse bones contain so little fat as not to be worth boiling for its extraction, aud are comparatively useless for any purpose save manuring the ground ; they are only indifferently valuable in that sphere, as the great percentage of lime they contain precludes their being economically treated with sulphuric acid before application to die soil. Fish bones are usually pressed, to remove the valuable oil which is present in considerable amount, and are then admioistered as a manure, without any furtber preparation.