Land.

Most animal substances, when exposed to a high temperature in close vessels, are converted into charcoal; but the animal charcoal inserted in the list of Materia Medica by the London College of Physicians is prepared chiefly from bones, or from ivory. But ivory black, or bone charcoal, requires to be purified by digestion in hydrochloric acid, in order to free it from carbonate and phosphate of lime, and afterwards washing out the muriates until the water passes off free from any saline matters. Pure animal charcoal should not yield bubbles when treated with hydrochloric acid; nor should the acid to which it has been subjected throw down a precipitate with sesquicarbonate of ammonia: the first mode of testing demonstrates the absence of carbonate of lime, the second that of the phosphate.

Uses. - Pure animal charcoal is only employed for the purpose of destroying the colouring matter which adheres to the crystalline products of some vegetable substances. Thus the second crystallization of morphia is dark coloured; but it becomes white when digested with animal charcoal.

Officinal preparations. - Aconitina, L. Morphiae Hydrochloras, L. Quince disulphas, L. Veratria, L.