_Industrial Applications of Bones._--By the increasing inventiveness of man, the industrial utilization of animal bone has been so developed that not one of the constituents fails to reappear in commerce. Composed of mineral matter--phosphates, &c.--fat and gelatinous substances, the phosphates are used as artificial manures, the fat is worked up by the soap-maker and chandler, and the gelatinous matter forms the basis of the gelatin and glue of commerce; while by the dry distillation of bones from which the gelatin has been but partially removed, there are obtained a carbonaceous residue--animal charcoal--and a tarry distillate, from which "bone oil" and bone pitch are obtained. To these by-products there must be added the direct uses of bone--for making buttons, knife-handles, &c.--when an estimate is desired of the commercial importance of these components of the animal frame. While most of the world's supply of bones goes to the glue and gelatin works, the leg and thigh bones, termed "marrows" and "knuckles," are used for the manufacture of bone articles. The treatment which they receive is very different from that practised in the glue-works. The ends are removed by a saw, and the bones are steeped in a 1% brine solution for three to four days, in order to separate the fibrous matter. The bones are now heated with water, and allowed to simmer for about six hours. This removes a part of the fat and gelatinous matter; the former rises as a scum, the latter passes into solution, and the bones remain sufficiently firm to be worked up by the lathe, &c. The fat is skimmed off, and, after bleaching, reappears as a component of fine soaps, or, if unbleached, the oil is expressed and is used as an adulterant of other oils, while the stearine or solid matter goes to the candle-maker; the gelatinous water is used (after filtration) for making size for cardboard boxes; while the bones are scrubbed, dried, and then transferred to the bone-worker.