Two kinds of carbon are officinal, namely, animal charcoal and wood charcoal.

1. Carbo Animalis

Carbo Animalis. Animal Charcoal. Bone Black.

Source. - Made by exposing bones to a red heat without the access of air.

Characters. - A black powder; contains only 10 per cent. of pure carbon, the rest consisting chiefly of phosphate and carbonate of lime.

Preparation.

Carbo Animalis Purificatus. - Purified Animal Charcoal. Animal Charcoal from which the salts have been almost wholly removed.

Source. - Made by digesting Animal Charcoal in Diluted Hydrochloric Acid, washing the undissolved part, and heating to redness in a closed crucible.

Characters. - A black powder, inodorous, and nearly-tasteless.

Dose. - 20 to 60 gr.

2. Carbo Ligni

Carbo Ligni. Wood Charcoal.

Source. - Wood charred by exposure to a red heat without access of air.

Characters. - Black, brittle, porous masses, without taste or smell, and retaining the texture of wood; contains about 2 per cent. vegetable ash.

Dose. - 20 to 60 gr.

Preparation.

Cataplasma Carbonis. - Wood Charcoal, Linseed Meal, Bread Crumb, and boiling Water,

Charcoal is also used pharmaceutically as a decolorising agent) in the preparation of such drugs as morphia and atropia.

Action And Uses

Externally. - Charcoal absorbs and condenses many gaseous bodies and vapours, as oxygen, carbonic acid, etc., and attracts the colouring, odoriferous, and sapid principles of many liquid substances, for example, litmus, bitters, wines, and decomposing liquids in general. It is used as a deodorant and disinfectant to absorb the foul emanations from cancerous and other discharges, ulcers, and wounds, being either hung around the bed in bags, or directly applied in dust, or as the poultice (a bad form.)

Internally - Charcoal is locally used as a dentifrice. When taken into the stomach in sufficient bulk, either pure, or in the form of biscuits, it absorbs any gas and acrid products of indiges-tion which may be distending and distressing the organ, and is useful as a carminative in some forms of flatulent dyspepsia. Animal charcoal has been recommended by Dr. Garrod as an antidote in poisoning by opium, nux-vomica, aconite, and other organic poisons, which it attracts from their solutions in the stomach, and renders inert. It is doubtful, however, whether the absorptive action of charcoal can be retained in the bowel, or even in the stomach, after it has been thoroughly brought in contact with water. In the intestines it may possibly reduce flatulence, deodorise the faeces, and thus reduce the reflex peristaltic movements, and relieve diarrhoea.

Charcoal is entirely evacuated by the bowel and is not absorbed, so that it exerts no specific action on the body.