The elements of materia medica and therapeutics: 2. Carbo Ligni. — Wood 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.
1854.

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¹ Hist. Nat. lib. ivi. cap. 7.

² Kidd's Outlines of Mineralogy, vol. ii. p. 47.

³ Traitè de Chimie appliquée aux Arts, I. i. p. 561.

⁴ For some further details, consult Mr. Wilkinsou's work on the Engines of War, London, 1841Carbo e ligno igue prreparatus, L. Carbo ligni, E. D.

History. — "Wood charcoal must have been familiar to man from the most remote period of antiquity, and was probably known to the first inhabitants of the globe. For an account of the ancient method of procuring it, I must refer the reader to the works of Theophrastus (cap x.) and Pliny.¹

Natural History. — Wood charcoal is always an artificial product. Some samples of Bovey coal have very much the appearance of wood charcoal, but are readily distinguished by their containing hydrogen, in consequence of which they burn with a yellow flame. Moreover they are not good conductors of galvanic electricity.²

Preparation. — Ordinary wood charcoal is prepared, on the large scale, for the purposes of fuel, by burning billet-wood (oak, beech, hazel, and sometimes willow), piled in a conical heap, covered with turf and sand, to prevent the access of atmospheric air, a few holes being left near the bottom and one at the top to occasion a draught. The heap is then set fire to, and when the flame has pervaded the whole mass, the holes are closed. When cooled, the billets are found converted into charcoal. For an account of the mode of arranging the wood in heaps, consult Dumas.³

The charcoal used in the manufacture of gunpowder is prepared by the distillation of wood in cast iron cylinders, set horizontally (or nearly so) in brick work, over a furnace. The charge is introduced at the front, and the opening is then perfectly secured by an iron door and bar, well luted. The back part of each cylinder is perforated by two pipes, one above the other, and bent downwards into tubs containing water. The tar flows out by the lower pipe, and the pyroligneous acid by the upper one, and condenses in the receiver (the tub). The smoke and vapours escape into the air. When sufficiently burnt, the charcoal is raked out into iron boxes, which are immediately covered, to exclude the air.⁴ At the Waltham Abbey mills, charcoal is prepared from the Dogwood (Cornus sanguinea) the Alder (Alnus glutinosa), and the Willow (Salix). The Dogwood charcoal (which occasions a peculiar ringing sound when it falls on stones) is used for rifle powder: the other kinds for cannon and musket powder. Lieut-Col. Moody tells me that the Dutch White Willow (Salix Russelliana?) is the best kind of willow for charcoal, but that the Huntingdon Willow is also a good one. (See Acidum Aceticum.)

Box wood charcoal for galvanic purposes is prepared by putting prismatic pieces of box wood, about an inch long and half an inch thick, into a crucible, covering them with dry sand, and exposing them to a red heat for about an hour.

Properties. — Wood charcoal is black, odourless, and insipid. It has the texture of the wood from which it has been obtained. It is brittle, and may be easily pulverised, especially when hot. Though a very bad conductor of heat, it is an excellent conductor of electricity. It is insoluble, infusible, and incapable of volatilization. Its specific gravity varies according to the substance from which it has been obtained. A remarkable property possessed by it is that of abstracting certain substances (such as hydrosulphuric acid, organic colouring principles, various odorous matters, &c.) from liquids in which they are dissolved, or through which they are diffused. Another curious quality is that of condensing within its pores a certain quantity of any gas with which it may be placed in contact. Thus one volume of boxwood charcoal absorbs 1.75 volumes only of hydrogen gas, but 90 volumes of ammoniacal gas. Some of the properties now mentioned (as that of decolorising) are possessed, in a more eminent degree, by animal charcoal.

Characteristics. — By combustion in oxygen gas, wood charcoal yields carbonic acid gas, — a property by which it is shown to consist of carbon. Its texture and appearance, as well as the nature of the ashes which it leaves behind when burnt, serve to distinguish it from other forms of carbon. (See Animal Charcoal).

¹ Traité des Estais par la Voie seche, t. i. p. 286, Paris, 1834.Composition. — The following is the composition of charcoal obtained from different woods, according to the experiments of Berthier¹
— | Poplar. | Maple. | Ash. | Fir. | Alder. | Birch. | Oak. | Hazel.
Carbon | 85.6 | 85.2 | 83.2 | 90.3 | 88.1 | 88.0 | 87.7
Calcined Ashes | 1.0 | 1.0 | 1.8 | 2.2 | 1.8 | 1.9 | 2.0 | 2.0
Volatile Matters | 13.4 | 18.8 | 15.0 | 7.5 | 8.0 | 10.0 | 10.0 | 10.3
Charcoal | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0


Wood ashes consist of soluble alkaline salts and of insoluble matters. The alkaline salts have for their base potassium and sodium: they contain (or yield) carbonic, sulphuric and hydrochloric acids, a little silica, and sometimes a trace of phosphoric acid. The insoluble matters contain carbonic and phosphoric acids, silica, lime, magnesia, and the oxides of iron and manganese. The quantity of carbonic acid is never sufficient to saturate both the alkalies and the earths, in consequence of the heat having expelled carbonic acid from the earthy carbonates. (See Potassa Carbonas.)

² Dict. de Mat. Med. par MM. Mérat et De Lens, t. ii. art. Carbone.

³ Traité de Matière Médicale, par S. Hahnemann, traduite par A. J. L. Jourdan, Paris, 1834.Physiological Effects. — Wood charcoal I believe to be an inert substance, both with respect to animals aud vegetables. Burdin² gave a pound of it daily without producing any other effect than that of blackening the stools. A variety of properties and virtues have, however, been ascribed to it, — as I believe, without foundation: thus it has been termed anodyne, emmenagogue, tonic, purgative, &c. In the French edition of Hahnemann's Materia Medica,³ no less than thirty-five pages are occupied with the enumeration of the symptoms produced by one-millionth of a grain of this substance ! !

Uses. — In this country, charcoal is used as a therapeutic agent, principally as a disinfectant and antiseptic, to absorb the fetid odour evolved by gangrenous and phagedenic ulcers. For this purpose it may be used in the form of powder or of poultice. Its disinfecting aud antiseptic powers, however, are much inferior to those of chlorine, or of the chlorides [hypochlorites] of lime and soda.

¹ Considération sur l'Usage du Carbone en Médecine, Paris, 1808.As a tooth-powder it is a valuable agent, freeing the teeth from the foreign matters which cover them, and at the same time counteracting the unpleasant smell of the breath arising from decayed teeth or disordered stomach; but it is apt to lodge in the space between the gum and tooth, forming an un sightly livid circle (see ante, p. 159). Brachet¹ states that it checks caries of the teeth. Areca-nut charcoal is a favourite variety for tooth-powders. Its fancied superiority is ascribed to the extreme hardness of its particles.

² Edinburgh Medical and Surgical Journal, vol. x. p. 13.Internally, charcoal has been exhibited in various affections of the alimentary canal, such as dyspepsia, cardialgia, diarrhoea, cholera, and dysentery. The beneficial effects said to have been produced in these cases can only be referred to the action of charcoal on the secretions of the bowels; an explanation apparently supported by Dr. Chapman's statement, that in dysentery, when the stools are highly acrid and offensive, charcoal entirely divests them of the bad smell and acrimony. In consequence of the advantage said to have been obtained by Dr. Calcagno, of Sicily, by the use of charcoal in intermittent, it was tried by Dr. Calvert, physician to the British forces at Palermo, and with success.² In this country, however, I believe it is never resorted to in ague by medical practitioners. Dr. Daniel, of Savannah, has recommended it in obstinate constipation, and in the nausea and confinement of the bowels which frequently attend pregnancy. It has also been used in various other diseases, but experience has not confirmed its efficacy.

Administration. — The dose of charcoal, as ordered by different writers, varies from ten grains to a tablespoonful or more.