Animal charcoal (carbo animalis) is prepared from bones, and 85 per cent. of it consists of mineral matter. It is called "bone-black." Purified animal charcoal is bone-black boiled with hydrochloric acid and washed thoroughly with water. It is almost pure carbon. Wood charcoal (carbo ligni) is prepared from soft wood; it is nearly pure carbon. Dose of charcoal, 15 to 60 grains (1 to 4 gm.). The larger dose makes a tablespoon-ful and for intestinal infections should be given four times a day mixed with cereal or other thick liquid.

Purified animal charcoal possesses the power, in a high degree, of adsorbing organic colors, hence is used largely in pharmacy and the arts for decolorizing, as in the refining of sugar and petroleum. It has a strong affinity for bacterial toxins, and has been used with success in dysentery, cholera, and other intestinal infections. It has also a certain amount of power to remove certain resins, bitter principles, and alkaloids from their solutions, and Lebourdais has in this way recovered digitalin, colo-cynthin, strychnine, quinine, and other active principles. Owing to this property, it has been proposed as a remedy in mushroom poisoning, arsenic poisoning, strychnine poisoning, etc. Unfortunately, this property of adsorption cannot be depended upon. Wood-charcoal and bone-black are very inferior as adsorbents.

In medicine, wood-charcoal has been used in flatulency because of its known power of adsorbing gases. But when saturated with liquid, it loses this power of gas adsorption, hence in fermenting stomach contents is of little or no value. In the study of the stools it is much employed in timing the passage through the alimentary tract. A dose of 30 grains (2 gm.) given with a meal will color the stool resulting from that meal black or gray-black. (See next article.)