This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
1. Charcoal. This is prepared by exposing wood, protected from the air, to a decomposing heat, by which the volatilizable matters are driven on0, and the carbon with a small proportion of saline and other substances is left behind. For medical use, according to Dr. Belloc, who had considerable experience with this remedy, it should be made from the lighter kinds of wood, such as the willow and the poplar; but it has since been ascertained by experiment, that the heavier woods yield charcoal of the greatest absorbent power; and, from the statements of Dr. Arthur Leared it appears that the most powerful of all the charcoals in this respect ' that obtained from the vegetable ivory nut. (Braithwaite's Retrosp., 1 86; from the Med. Mirror, June, 1865, p. 315.) The volatile matter should be completely driven off, the resulting charcoal then macerated in water to separate soluble impurities; and, lastly, it should be thoroughly dried, put into bottles, and secured from the contact of the air.
An extraordinary property of charcoal, on account of which it is introduced here, is that of absorbing and condensing in its pores large quantities of different gases, and of exercising a similar influence over odorous, sapid, and colouring matters contained in organic products. it is thus, probably, that it is enabled to correct putrescency in animal matters, and it is thus, I have no doubt, that it sometimes proves useful as a remedy in the alimentary canal. in this situation, as elsewhere, condensing the offensive gases, it prevents their absorption and consequent elimination, and thus corrects foul breath. in like manner, abstracting from the alimentary contents any acrid, irritating substance, and among the rest acids, it retains them within its pores, and consequently obviates their irritant influence.
The affections, therefore, in which charcoal is indicated, are foul breath; putrid or otherwise offensive discharges, as in bad cases of dysentery; gastrodynia, cardialgia, spasm of the stomach and bowels, and other disorders which may be supposed to depend upon irritant matter in the primae viae. Consequently, cholera and diarrhoea are among the complaints in which it may be given.
The dose is quite indefinite, as the remedy probably exercises no deleterious influence directly on the tissues. From half a drachm to half an ounce may be given at once, and repeated several times a day; care being taken, by the simultaneous use of cathartics, if necessary, to prevent accumulation and consequent obstruction of the bowels. As charcoal, already saturated more or less with gases and water, has lost proportionately of its absorbing power, it is recommended by Dr. Leared that, when intended for medical use, after having been ignited so as completely to drive off its gas and moisture, it should, immediately after cooling, be enclosed in gelatin capsules, and in this condition swallowed. (Braithwaite, loc. citat.)
As a dentifrice, charcoal is useful not only by brightening the teeth, through the hardness of its minute particles, but by correcting the foul breath proceeding from carious teeth.
As an external application, it is employed, with the same view, in sloughing ulcers, burns, etc., where there may be offensive exhalations. For this purpose it is generally used in the form of cataplasm. The following formula for this is given by the British Pharmacopoeia, under the name of Cataplasma Carbonis. Two ounces of bread, having been macerated near the fire, for a little while, with ten fluidounces of boiling water, are then mixed thoroughly with it, and, at the same time, with an ounce and a half of flaxseed meal gradually added. With the cataplasm thus made, two drachms of powdered charcoal are to be incorporated, and one drachm sprinkled on its surface.
2. Animal Charcoal. This is prepared by exposing bones, previously boiled in water to separate their oil, to a red heat in close vessels. The carbon is left behind, mixed with phosphate and carbonate of lime, from which it may be separated by digestion in diluted muriatic acid, and subsequent washing. Thus prepared, it is called purified animal charcoal (Carbo Animalis Purificatus, U. S., Br.). in this condition it has extraordinary absorbing powers, in reference to various colouring, odorous, and sapid substances, and is much used in chemical processes for the purposes of decolorization.
This absorbing power extends even to the active principles of vegetables; and it has long been known that, in decolorizing the vegetable alkaloids, in the processes for their preparation, allowance must be made for loss in the alkaloid product in consequence of this property of the charcoal.
Dr. Garrod has inferred from his experiments, in reference to a number of the poisonous vegetable principles, that animal charcoal might be employed as an antidote, in consequence of this property of absorbing and holding on to the poisonous matter, so as to prevent its entrance into the circulation. Though frequently repeated trial would be necessary to establish an undisputed claim to the possession of this antidotal power; yet its use in cases of poisoning from the vegetable alkaloids, as strychnia, atropia, aconitia, etc., would be not only admissible, but advisable; as it is in itself harmless, and would not interfere with other agencies that might be deemed necessary, as the evacuation of the stomach, etc. The quantity of charcoal required is large; not less, according to Dr. Garrod, than half an ounce for each grain of the poisonous principle. Neither vegetable charcoal, nor the unpurified animal charcoal will answer the purpose.