Charcoal, Animal

Syn. Animal black , Bone black , Ivory black , Carbo animal is . The charcoal obtained by igniting bone in close ve els, but often applied likewise to any charcoal obtained from animal matter. Commercial. Bones (deprived of their grease by boiling) are broken to pieces, and put into small cast-iron pots, varying from 3 ⁄ 8 to 1 ⁄ 2 an inch in thickne . Two of these being filled, are dexterously placed with their mouths together and then luted with loam. A number of these ve els are then placed side by side and piled on each other, in an oven resembling a potter’s kiln, to the number of 100 or 150, or even more. The fire is next kindled, and the heat kept up strongly for 10 or 12 hours, according to circumstances, until the proce is completed. The whole is then allowed to cool before opening the pots. A more economical method is by distillation, as under:— Bones (previously boiled for their grease) are introduced into retorts similar to those used in gas works, and heat being applied, the volatile products are conveyed away by iron pipes to cisterns where the condensable portion is collected. As soon as the proce of distillation is finished, the solid residuum in the retorts, while still red hot, is removed through their lower ends into wrought-iron canisters, which are instantly closed by air-tight covers and luted over. These are then raised to the ground by a crane, and set aside to cool. The bones, having been carbonised, are ground in a mill, and the resulting coarse powder, sorted by sieves into two kinds, one, granular, somewhat resembling gunpowder, for decolorising liquids, and the other, quite fine, to be used as a pigment. The first is sold under the name of animal charcoal; the second as bone or ivory black. The latter and other fine varieties of animal charcoal are fully described under the head of Black pigments . Uses, . This crude animal charcoal po e es the valuable property of taking lime and other saline matter from syrups and other aqueous solutions, especially organic ones, at the same time that it decolours them. Its power as a decoloriser may be tested by adding it to a solution of brown sugar or of mola es, or to water containing 1 ⁄ 1000 part of indigo di olved in sulphuric acid. The test should be made in a small gla tube. By well washing and carefully reburning it, this charcoal may be used any number of times. As a decoloriser and deodoriser, animal charcoal is vastly superior to vegetable charcoal. Dr Sten house has invented a charcoal respirator to cover over the mouth and nostrils of a person going into an infected atmosphere. Charcoal is also used with excellent effect to prevent the escape of noxious vapours and offensive effluvia from the ventilating openings of sewers. The charcoal condenses and oxidises the escaping sewer gas in its pores. Dr Garrod has proposed animal charcoal as a general antidote in cases of poisoning. Prepared Animal Charcoal. Hydrochloric acid, 1 lb.; water, 1 pint; mix, add bone black, 7 lbs.; make a paste; in 2 or 3 days stir in boiling water, 1 quart; and the next day wash it with fresh water until the washings cease to affect litmus paper or a solution of carbonate of sodium; then collect it in a cloth, and drain, pre , and dry it; lastly, heat it to redne , as before. Used to decolour syrups, .; and occasionally by the distillers and rectifiers. The most powerful charcoal is prepared by calcining blood, and well washing the residue, and which is the method of the last ‘London Pharma copœia.’ The B. P. directs it to be made by burning bones in a closed ve el. Concluding Remarks. Animal charcoal, however prepared, if intended to be used as a deodoriser or decoloriser, should be kept thoroughly excluded from the air, as by exposure it loses all its valuable properties, and becomes absolutely inert. Freshly burnt charcoal is therefore to be employed whenever it can be obtained.