692 
the vessels. He found it to exhibit precisely the 
same properties as the air which results from the 
combustion of charcoal. This experiment was 
also performed by Morveau, who demonstrated 
the nature of the diamond by still another ar- 
rangement. A diamond was enclosed in a cavity 
made in a piece of pure, soft iron; a stopper of 
the same metal was driven into it, and the mass 
was put into a small crucible, which was covered, 
and this into a second ; the space between them 
being filled with pure silicious sand. The whole 
was exposed, for some time, to an intense heat. 
When examined, the diamond had disappeared, 
and the iron, with which it had been in contact, 
was converted into steel. Now steel is a com- 
pound of iron and carbon; and, as the diamond 
was not visible, and as there was no source from 
which the carbon could have been obtained, the 
conclusion was unavoidable, that the diamond 
was pure carbon. Yet so different is this mine- 
ral from charcoal, that it was, for a time, ima- 
gined that it contained some other element than 
carbon; but the numerous and delicate experi- 
ments of Sir H. Davy, and several other chemists, 
failed of detecting any thing else in its composi- 
tion; and, although there exists so great a dif- 
ference between the diamond and charcoal, in 
their external properties, we are forced to believe 
that they are identically of the same nature. 
The diamond is, therefore, pure carbon, and dif- 
fers from charcoal (leaving out of question its 
trifling impurities) only in the arrangement of its 
molecules. 
The substance in which carbon exists next in 
purity is charcoal. For common purposes, this 
is prepared by piling billets of wood in a pyrami- 
dical form, with vacuities between them for the 
admission of air, covering them with earth, and 
inflaming them. In consequence of the heat, 
part of the combustible substance is consumed, 
part is volatized, together with a portion of 
water, and there remains behind the ligneous fibre 
only of the wood, in the form of a black, brittle, 
and porous body. When required pure, and in 
small quantities, for the purposes of the chemist, 
it may be obtained by immersing the wvod in 
sand contained in a crucible exposed to heat. 
According to the experiments of Messrs. Allen 
and Pepys, the weight of charcoal obtained from 
100 parts of different woods was as follows :—fir, 
18:17; lignum vite, 17:25; box, 20°25; beech, 
15; oak, 17°40; mahogany, 15°75. 
Lampblack is charcoal in a state of minute di- 
vision, and is prepared for the demands of trade 
from the dregs which remain after the eliquation 
of pitch, or else from small pieces of fir-wood 
which are burned in furnaces of a peculiar con- 
struction, the smoke of which is made to pass 
through a long horizontal flue, terminating in a 
close, boarded chamber. The roof of this cham- 
ber is made of coarse cloth, through which the 
current of air escapes, while the soot, or lamp- 
black remains behind.—Cofe is a peculiar kind of 
CARBON. 
charcoal, which remains in the retort, after the 
heating of coal to procure the coal gas.—Ivory- © 
black, or animal charcoal, is obtained from bones 
made red-hot in a covered crucible, and consists 
of charcoal mixed with the earthy matters of the 
bone.—W ood charcoal, well prepared, is of a deep- 
black colour, brittle, and porous, tasteless and 
inodorous. It is infusible in any heat a furnace 
can raise; but, by the intense heat of a powerful 
galvanic apparatus, it is hardened, and at length 
is volatilized, presenting a surface with a distinct 
appearance of having undergone fusion. The 
density of charcoal, according to Mr. Leslie, is 
little short of that of the diamond itself, although 
its specific gravity has usually been considered 
as low as 2:00. Charcoal is insoluble in water, 
and is not affected by it at low temperatures ; 
hence wooden stakes, which are to be immersed 
in water, are often charred to preserve them.— 
Owing to its peculiarly porous texture, charcoal 
possesses the property of absorbing a large quan- 
tity of air, or other gases, at common tempera- 
tures, and of yielding the greater part of them 
when heated. It appears, from the researches of 
Saussure, that different gases are absorbed by it 
in different proportions. He found that charcoal 
prepared from box-wood absorbs, during the space 
of 24 or 36 hours, of 
Ammoniacal gas, 90 times its volume; © 
Muriaticacid, . 85 do. 
Carbonic acid, 35 do. 
Oxygen, 9°25 do. 
Hydrogen, 175 ~— do. 
Charcoal likewise absorbs the odoriferous and 
colouring principles of most animal and vegcta- ~ 
ble substances. Thus, all saline substances, 
which, from the adherence of vegetable or animal 
extractive matter, are of a brown colour,—as 
crude tartar, crude nitre, impure carbonate of 
ammonia, and other salts, may, after being di- 
gested through the medium of water with char- 
coal, be obtained white by a second crystalliza- 
tion. Resins, gum-resins, assafoetida, opium, 
balsams, essential oils, and many other substances, 
even those that have the strongest smell, are 
rendered nearly inodorous when they are rubbed 
with charcoal and water, or when solutions of 
them in alcohol are macerated with the charcoal, 
or filtrated repeatedly through it. A number of 
the vegetable tinctures and infusions also lose 
their colour, smell, and much of their taste, by 
the same process. Common vinegar, on being 
boiled with charcoal powder, becomes colourless. 
Malt spirit, by distillation with charcoal, is freed 
from its disagreeable flavour. In the same man- 
ner wines, also, become colourless, and distilled 
waters lose their odours. Water, which, from 
having been long kept in wooden vessels, as dur- 
ing long voyages, has acquired an offensive smell, 
is deprived of it by filtration through charcoal 
powder, or even by agitation with it for a few 
minutes, especially when a few drops of sulphuric 
Hence, also, it has 
acid have also been added. 
