[bohn-blak] 
| a black, carbonaceous substance obtained by calcining bones in closed vessels, used as a black pigment, a decolorizing agent, etc. |
| bone·black also bone black (bōn'blāk') n. A black pigment containing about 10 percent charcoal, made by roasting bones in an airtight container and used in polishes, as a filtering medium, and in decolorizing sugar. Also called bone charcoal. |
bone black
a form of charcoal (q.v.) produced by heating bone in the presence of a limited amount of air. It is used in removing coloured impurities from liquids, especially solutions of raw sugar. Bone black contains only about 12 percent elemental carbon, the remainder being made up principally of calcium phosphate and calcium carbonate.
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