Animal Charcoal, when intended for medicinal purposes, is best obtained by calcining leather scraps or blood with pearlash, washing and re-heating the same in a close crucible. By these means a very good pure charcoal is obtained, and was that employed by Dr. Garrod in his experiments (infra). "Bone, Ivory, or Animal Black" contains only about 10 to 18 per cent. of Animal Charcoal.

Carbo Animalis Purificattjs. Purified Animal Charcoal of the British Pharmacopoeia is prepared by adding 16 oz. of Bone Black to 10 fl oz. of Hydrochloric Acid, diluted with 1 pint of Distilled Water and stirring occasionally. The mixture is digested at a moderate heat for two days, and agitated from time to time; the undissolved charcoal is then collected on a calico filter and washed with Distilled Water till what passes through gives scarcely any precipitate with Nitrate of Silver. The charcoal is then dried and heated to redness in a covered crucible. In this process the charcoal is freed from the phosphate and carbonate of lime and the sulphide of calcium.

* Association Med. Journal, Aug. 10, 1858, p. 742.

Med. Prop. and Action. Used in pharmacy as a decolorising agent. Like Wood Charcoal, it may be employed as a deodorizer and antiseptic. As an antidote in poisoning by certain vegetable substances, the alkaloids, &c, it was first proposed by Dr. Garrod.* The results of his experiments, and those of Wapen, Graham, and Chevalier Rand, may be summed up in the following articles: -

1. Animal charcoal is capable of removing from their solutions, in some cases only by the aid of heat, the bitter, resinous, and active principles of Quassia, and the other simple bitters; of Colocynth, Aloes, and other purgatives; of Krameria, and other astringents; of Guaiacum, Cinchona, Opium, Nux Vomica; and, in short, all vegetable substances submitted to its influence.

2. That It Precipitates From Their Solutions A Large Number Of Oxides

The acid salts, Arsenious acid, the Arsenites of Potassa and Soda, the acid nitrate of Mercury, the cyanide and ferrocyanide of Potassium, are exempt from its action.

3. That it has the power of combining in the stomach with the poisonous principles of animal and vegetable substances, and that the compounds thus produced are innoxious; therefore, when given before these poisons have become absorbed, it will act as an antidote.

4. That A Certain Amount Of Animal Charcoal Is Required, About Ss

to each grain of Morphia, Strychnia, or any other alkaloid; but of course much less forthe substances from which they are obtained, as Opium, Nux Vomica, &c. Gr. xx of Nux Vomica requires about ss of Charcoal.

5. That The Antidote Itself Exerts No Injurious Action On The Body

6. That when given as an antidote, it should be mixed with water as hot as the patient can swallow, as its action is much aided by an elevated temperature, Dr. Taylor and Dr. Pereira§; agree in regarding the experiments adduced as inconclusive. They admit that it is certainly capable of acting mechanically, and thereby impeding the action of poisons; but beyond this they deny its antidotal power. The weight of evidence is decidedly in favour of its efficacy, and it should never be neglected when opportunity offers of testing its real value.