Bone-ash

Bone-ash, or BONE-EARTH, is obtained by the complete combustion of bones in an open furnace, when the oxygen of the air burns away the organic matter or gelatin, and leaves the earthy constituents as a white friable mass, the size of the original bone, but readily reducible to the condition of coarse powder which is bone-ash. A very large quantity of bone-ash is exported from South America to other countries, especially Britain. The used-up bone-black of the sugar-refiner is also employed as a source of bone-ash, by being heated in a furnace exposed to the air. Bone-ash of good quality contains about 80 per cent. of phosphate of lime, and 20 per cent. of carbonate of lime, phosphate of magnesia, soda, and chloride of sodium (common salt); but it is occasionally found mixed with sand, especially that procured from South America. Bone-ash is employed to some extent as a source of Phosphorus (q.v.), and in the making of Cupels (q.v.) for the process of Assaying (q.v.); but the most extensive use is in the manufacture of artificial manures, such as Dissolved Bones (q.v.) and superphosphates.