The elements of materia medica and therapeutics: 3. Carbo Animalis. — Animal Charcoal.

The elements of materia medica and therapeutics
by Jonathan Pereira, M.D. F.R.S. & L.S.
Fourth Edition, enlarged and improved, including notices of themost of the medicinal substances in use in the civilized world, and forming an Encyclopædia of Materia Medica.
Vol. I.
London: printed for Longman, Brown, Green, and Longmans, Paternoster Row.
(Carbo e sanguine bovino igne pneparatus, L. Carbo animalis, E. D.)

History. — This substance must have been known from the most ancient times. The kind usually met with in the shops is prepared from bones, and is termed bone black or animal black. It is sometimes sold as ivory black (ebur ustum nigrum).

Preparation. — Animal charcoal is extensively manufactured from bones for the use of sugar-refiners; and during the process an ammoniacal liquor (called bone spirit) is obtained as a secondary product. The operation is thus conducted: —

Bones are first boiled to remove the fatty matter which is used in soapmaking. The larger and finer pieces are then selected for the manufacture of buttons, handles of knives and tooth-brushes, &c; while the smaller and refuse portions are sold as manure. The remainder is submitted to distillation.

1 See Ure's Dictionary of Arts and Manufactures, p. 10S1, figs. 951 aud 955, London, 1839.The stills or retorts are sometimes made of cast iron, and in shape and size resemble those used at gas-works. Formerly they were placed horizontally in the furnace,1 and the volatile matters were conveyed away by a pipe opening into the ends of the retorts. To facilitate the speedy removal of the charcoal, they are sometimes placed obliquely in the furnace: the bones are introduced at the upper end, and the charcoal is removed from the lower end; — while the volatile matters are conveyed away by a side pipe. But these retorts are considered inferior to the vertical ones, on account of the facility and speed with which the latter can be charged and discharged. The vertical stills or retorts are made either of cast iron or of Welsh bricks; the latter, I am informed, are preferable. In a large manufactory of animal charcoal in this metropolis, the shape of the retort is that of a right rectangular prism; its height being twenty feet, its length about three feet, and its breadth two feet. It is closed at the top by a movable iron plate, secured by a screw bolt. It is closed below by a double trapdoor opening underground. Around the retort is a furnace of brickwork, whose shape is that of a truncated pyramid.

a. Furnace inclosing the retort.
b. Top of the retort.
c. Pipe to convey away the volatile products.
d. Water cistern, through which the volatile matter passes.
e. Pipe leading to
f. The iron receiver (an old steam boiler), com municating with a reservoir cistern under ground.
g. Second receiver.
h. Chimney inlo which the residual vapour passes.
i. Furnace door.
k. Crane.
l. Canister to receive the charcoal.
m. Steps leading to the lower end of the retort.

The bones are introduced at the upper end of the retort (b). The volatile products are conveyed away by the iron pipe (c). After passing through the cistern (d) they are conveyed to a series of receivers (f and y), where the brown ammoniacal liquor (bone spirit) and the empyreumatic oil (animal oil) are deposited. The uon-condensible portion is a fetid inflammable gas: this, after passing through water contained in the second receiver, is conveyed into a chimney, or is burned. The sobd residue in the retort is removed, while red-hot, through the lower and underground end of the retort, into wrought-iron canisters (I), which are instantly closed by iron covers, luted to make them air-tight, and then raised to the surface by a crane (k). When cold it is ground, and sold as animal, bone, or ivory black.

The volatile products of this operation are easily accounted for. When bones are heated, their cartilaginous or gelatinous portion uudergoes decom position, and its elements enter into new combinations. Some of the oxygen and hydrogen unite to form water. Carbon and oxygen, combining in dif ferent proportions, furnish carbonic oxide and acid. Carbon with hydro gen forms carbohydrogen; while nitrogen uniting with hydrogen produces ammonia, which, with some carbonic acid, forms carbonate of ammonia. The empyreumatic or animal oil consists of carbon, hydrogen, and oxygen, with probably some nitrogen.

Properties. — In its general properties animal charcoal agrees with char coal procured from wood. It is denser and less combustible than wood charcoal, but greatly exceeds the latter in its power of destroying colour and odour. In the crude state (carbo animalis crudus) it occurs in four forms in commerce: unground, and retaining the shape of the bones from which it was procured; coarsely ground (grain animal charcoal), as used by the sugar-refiners; more finely ground (coarse grit animal charcoal), as used by distillers; and finely ground or pulverised (fine animal charcoal). In the latter state it is frequently damped, and sold, at a lower price, as ivory black to the makers of blacking, &c.

Characteristics. — Animal charcoal yields, when burnt in oxygen gas or atmospheric air, carbonic acid, like other forms of carbon. From vegetable charcoal it may be distinguished by its texture and appearance, as well as by the nature and properties of its ashes. To obtain the ashes for examination a portion of the charcoal should be burned on a red-hot iron into white ashes. Wood ashes dissolve in sulphuric acid, and yield a bitterish solution: bone ashes are very sparingly affected by that acid, and form with it a compound having a very different taste.

1 Dumas, Traité de Chimie, t. i. p. 450, Paris, 1828Composition. — Animal charcoal, prepared by calcining the bones of the ox, sheep, and horse, consists of the following ingredients:1
Phosphate of lime
Carbonate of lime } ... 88.0
Charcoal ... 10.0
Carburet or siliciuret of iron ... 2.0
Sulphuret of calcium or iron ... traces
Common Bone Black ... 100.0

The proportion of charcoal here stated is certainly small. Dr. Christison states that he has found, in the animal black of this country, usually about 20 per cent, of charcoal. When bone black is calcined in the open air, the carbon is burnt off, and a whitish residue is obtained, called bone ash. (See Calcis Subphosphas.)

For the ordinary purposes of the arts, as sugar-refining, crude animal char coal answers very well, because the earthy salts in no way affect the process. But in various pharmaceutical operations the presence of phosphate and carbonate of lime would preclude its use, on account of the free acid in the liquids to be decolorised. Hence the necessity of the purification of animal charcoal. (See Carbo animalis purificatus, p. 326.)

Animal charcoal, when deprived of its saline matters, usually contains traces of nitrogen. Dobereiner, indeed, supposed it to be a kind of subnitruret of carbon, composed of one equivalent or 14 parts of nitrogen, and six equivalents or 36 parts of carbon. Bussy, however, has shown, that though animal charcoal retains its nitrogen with considerable obstinacy, yet that the latter may be separated by heat.

Physiological Effects. — The remarks already made in reference to the physiological effects of wood charcoal apply equally well to animal charcoal.

1 Pharmaceutical Journal, vol. ix. p. 78.

2 Journal de Pharmacie, t. viii. p. 257, 1822.
Uses. — The principal use of animal charcoal is as a decolorising agent in various pharmaceutical processes, as in the refining of sugar, the preparation of disulphate of quina, hydrochlorate of morphia, veratria, &c. The superior value of animal to vegetable charcoal for this purpose is usually referred to the minute separation of the carbonaceous particles effected by the presence of other matters, as of phosphate of lime, when bones are employed. Carbonate of potash is better for this purpose than phosphate of lime. The property possessed by minute particles of charcoal, of abstracting colouring matter from liquids, depends, probably, on some chemical affinities existing between carbon and colouring matter. It has been stated that charcoal which has been once used cannot have its decolorising property restored by a fresh ignition, unless it be mixed with some inorganic substance. This, however, is an error. The animal charcoal which has been used in sugar-refining is returned to the maker to be freshly ignited, and is then employed again, and this process of re-igniting is repeated many times, without any loss of decolorising power. [Animal charcoal can scarcely be regarded as a proper decoloriser in the preparation of the alkaloids, as it appears that many of these substances become removed from solution when digested with it. Morphia and strychnia are so affected, according to the experiments of Dr. Band, of Philadelphia.1 — Ed.]

The following table, drawn up by Bussy,2 shows the decolorising power of charcoal for indigo and molasses. The indigo test liquor contained 1/1000th of this substance; and, therefore, every gramme of the solution decolorised represents a millegramme (=0,0154 troy gr.) of indigo absorbed by the charcoal. The molasses solution consisted of one part molasses and twenty parts of water.
Kind of Charcoal employed.
(Weigh talways 1 gramme = 15.434 troy grains.)
Solution of Indigo decolorized
Solution of molasses decolorized
Decolorizing power on Indigo.
Decolorizing power on Molasses.
1. Bone charcoal 22 9 1.001.00
2. Vegetable or animal oil charred with phosphate of lime64172.001.90
3. Bone charcoal washed with hydrochloric acid60151.871.60
4. No. 3 calcined with potash145018045.0020.00
5. Calcined lamp-black128304.003.30
6. no. 5 calcined with potash5509015.2010.60
7. Charcoal of carbonate of soda decomposed by phosphorus3808012.008.80
8. Charcoal of acetate of potash180405.604.40
9. Starch charred with carbonate of potash3408010.608.80
10. Albumen charred with potash108014034.0015.50
11. Gelatine charred with potash115014036.0015.50
12. Blood charred with phosphate of lime3809012.0010.00
13. Blood charred with chalk57010018.0011.00
14. Blood charred with potash100018050.0020.00

1 Warington, Memoirs of the Chemical Society, vol. ii. p. 326, 1845; also Weppeu, Pharmaceutical Journal, vol. v. p. 326, 1846.The effect of animal charcoal in removing substances from their solutions is not limited to colouring matters: it also deprives liquids of their bitter principles, alkaloids, resins, tannin, and even some metallic salts.1 It is obvious, therefore, that it cannot be employed to decolorise poisonous liquids, since it deprives the solution of more or less of its deleterious ingredient, as well as of its colouring matter. Moreover, it is clear that manufacturers who employ animal charcoal to decolorise their solutions must lose part of their product; and hence in the preparation of disulphate of quina, &c. a loss must be sustained by the employment of charcoal as a decoloriser.

2 Pharmaceutical Journal, vol. v. p. 325, 1846.

3 On Poisons, p. 84, 1848.
Dr. Garrod2 has recently proposed purified animal charcoal as a general antidote in cases of poisoning; but I agree with Dr. Taylor3 in regarding the experiments adduced in favour of it as inconclusive. Like many other agents it is certainly capable of acting mechanically, and of thereby impeding the action of poisons (see ante, pp. 158, 159, and 165), but beyond this there is no evidence of its antidotal power.

CARBO ANIMALIS PURIFICATUS, E.D.; Purified Animal Charcoal. — The Edinhurgh College directs a mixture of lb. j. of Animal Charcoal and f?xij. each of Water and of Hydrochloric Acid to be boiled, after digestion for two days; then dilute with two pints of water: the undissolved charcoal, collected in a filter of linen and calico, is to be washed with water till what passes through scarcely precipitates with solution of carbonate of soda. The charcoal is to be heated first moderately, and then to redness in a closely covered crucible. — In this process the hydrochloric acid dissolves the phosphate of lime, and decomposes the carbonate of lime and sulphuret of calcium, evolving carbonic and hydrosulphuric acid gases, and forming chloride of calcium, which remains in solution. The carbonate of soda, used by the Edinburgh College, is for the purpose of detecting the presence of a calcareous salt in the washings.

The formula of the Dublin College is as follows: —

"Take of Ivory Black, lb. v.; Muriatic Acid of commerce, Oiij.; Water, Cong. ni. Oiij.; Distilled Water, as much as is necessary. To tho acid, diluted with Oiij. of water, gradually add tho ivory black, and digest, with repeated stirring, at a gentle heat, for twenty-four hours. Pour on now a gallon of water, and when, after the mixture has been well agitated, the insoluble matters have subsided, remove the clear solution by decantation, or the syphon. Let this be done a second and a third time. Place now the black sediment on a calico filter, and wash it with distilled water until the washings cease to give a precipitate with nitrate of silver. Finally, let the product be dried in a stove or oven, a gentle heat being at first applied, which must be finally raised to between 300° and 400°."

Purified animal charcoal causes no effervescence when mixed with hydro chloric acid, by which the absence of carbonate of lime is shown. Nor is any precipitate produced by the addition of ammonia, or its sesquicarbonate, to the acid which has been digested in the charcoal, by which the absence of any dissolved calcareous matter is shown: caustic ammonia would precipitate any phosphate of lime in solution, while its sesquicarbonate would yield a white precipitate with chloride of calcium. Purified animal charcoal, "when incinerated with its own volume of red oxide of mercury, is dissipated, leaving only a scanty ash [about 1/200th]." — Ph. Ed.

Purified animal charcoal is used as a decolorising agent in the preparation of the vegetable alkaloids, and as an antidote to poisons.

[Experiments by MM. Wassen and Graham, and also Drs. Garrod and Rand, seem to prove that the alkaloids, and some mineral poisons also, are prone to combine with purified animal charcoal, and become inert if sufficient of this latter substance be administered.

1 Pharmaceutical Journal, vol. ii. p. 78.Dr. Garrod considers that animal charcoal has greater power of removing arsenic from its solutions than has the hydrated sesquioxide of iron; but tins is opposed to the results of the other above-mentioned experimenters.1 — Ed.]

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