This element is employed in medicine in the form of animal and vegetable charcoal.

Carbo Ligni, B.P. and U.S.P. Wood Charcoal. - Wood charred by exposure to a red heat without access of air, B.P. Charcoal prepared from soft wood, U.S.P.

Characters. - In black, brittle, porous masses, without taste or smell, very light, and retaining the shape and texture of the wood from which it was obtained. When pulverised it forms a fine black powder.

Preparation. - It is prepared either by burning the wood under turf, or in retorts, so that the hydrogen and oxygen are driven off and charcoal alone remains. If too much air be allowed to have access, the charcoal itself becomes burnt, and too large a proportion of ash comes to be present.

Impurities. - Too much ash.

Tests. - When burned at a high temperature with free access of air it leaves not more than two per cent. of ash.

Dose. - 20-60 grains.

Officinal Preparation. B.P. U.S.P.

Cataplasma Carbonis. None.