CARBON. 
rooms, which the keepers of the caravanseras 
let out, at a very high price, to such as have 
a mind to be private.. The caravanseras in 
the East are something in the nature of the 
inns in Europe, only that you meet with 
little accommodation either for man or 
beast, but are obliged to can-y almost every 
thing "with you ; there is never a caravansera 
witliout a well or spring of w’ater. These 
buildings are chiefly owing to the charity of 
the Mahometans: they are esteemed sacred 
dwellings, where it is not permitted to in- 
sult any person, or to pillage any of the 
effects that are deposited there. They 
even carry their precautions so far, as not 
to suffer any man who is not married to 
lodge there ; because they are of opinion, 
that a man who has no wife is more dan- 
gerous than another. 
CARBON, in ehemistry. The term car- 
bon having been understood in different 
senses, and having been actually applied to 
different substances, it is necessary to guard 
against the ambiguity arising from this cir- 
cumstance, and with this view to trace in a 
general manner the progress of those disco- 
veries from which the name originated, and 
by which its application has since been 
changed. . 
When vegetable matter, especially the 
more solid parts of plants, the wood for ex- 
ample, is exposed to heat in close vessels, 
it is decomposed ; the more volatile prin- 
ciples are disengaged, and there remains a 
black, shining, porous body, composed of 
the various substances which are not con- 
vertible by a high temperature to the gase- 
ous form. This substance is termed char- 
coal. While the atmospheric air is exclud- 
ed, it is neither fused nor volatilised by any 
increase of heat; but when the air is ad- 
mitted, it suffers combustion, and it conti- 
nues to burn tilt nearly the whole of it is 
consumed ; the residuum amounting to not 
more than the 200tb part of tlie weight of 
the original charcoal. This residuum is un- 
inflammable, and consists principally of 
saline and metallic matter. Charcoal then 
is a heterogeneous substance. By far the 
greater part of it consists of an inflammable 
substance which combines with oxygen, 
and forms the carbonic acid of the modern 
nomenclature. Bat this inflammable mat- 
ter, as it exists in the charcoal, is mixed or 
combined with the saline and metallic sub- 
stances left after its combustion. For the 
sake of precision, a distinction is made in 
the new nomenclature between the pure 
inflammable base and the substance in which 
it is thus presented to us. Qiarcoal is that 
black porous substance obtained from vege- 
table matter, especially from wood, by ex- 
posing it to heat ; and the pure inflannnable 
substance, which composes by fai' the 
greater part of the charcoal, was termed 
carbon. Carbon, therefore, aecording to 
this signification, was charcoal destitute of 
the small quantity of saline and metallic 
matter usually mixed with it. The princi- 
pal advantage of the introduction of the 
name carbon, was not merely that of dis- 
tinguishing the inflammable base from the 
substance in which it was mixed with other 
ingredients ; but also that of givkig a term ca- 
pable of combination, and of affording those 
derivative appellationswhich the modern sys- 
tem requires. This substance is not a hy- 
pothetical being, since, by certain chemical 
processes, by tbe decomposition of carbonic 
acid for instance, or of alcohol by heat, it is 
possible to obtain it perfectly pure. It 
exists in a large quantity as a component 
part of vegetable substances ; it enters into 
the composition of animal matter, and is 
contained in substances belonging to the 
mineral kingdom. This substance, which 
when it is obtained pure exists in the form 
of a very light black powder, was, until 
within these few years, considered as a 
simple body ; but experiments have proved, 
that it is a compound, containing an inflam- 
mable substance, according to some ehe- 
mists, in a state of imperfect oxydation; 
according to others, combined with hydro- 
gen. It had been known for a considerable 
time, that the diamond, the most beautiful 
and most unchangeable of the productions 
of nature, is combustible, or that when heat- 
ed with oxygen gas it suffers combustion. 
Lavoisier made some experiments to ascer- 
tain the nature of the product of this com- 
bustion ; and he found it to be an acid pre- 
cisely the same with that which is produced 
by the buraing of charcoal — what is termed 
the carbonic acid. He did not, however, 
ascertain the proportion of it with sufficient 
accuracy to draw any precise conclusion. 
Some time after, Mr. Tennant repeated the 
experiment of oxydizing the diamond, by 
exposing it to heat along with nitrate of pot- 
ash in a gold tube. He also found that 
carbonic acid was formed ; and from ^n ex- 
periment on a small scale, it appeared that 
about the same quantity of carbonic acid 
was afforded by the oxygenation of the 
diamond as would have been produced by 
the combuistion of the same weight of char- 
coal. He concluded that the diamond wax 
