CAR 
carbon, and differed from charcoal princi- 
pally in its form and state of aggregation; 
that in short it might be considered as car- 
bon crystallized. 
At length Guyton resolved to, examine 
this subject, and his experiments afforded 
very important results. The diamond on 
which he experimented was burnt in a ves- 
sel of oxygen gas, by directing the solar 
rays upon it through a very powerful lens. 
It assumed at first a leaden colour ; by the 
farther continuance of the heat its surface 
appeared charred. At length it appeared 
sensibly to diminish, and in little more than 
an hour and a half was entirely consumed. 
The product of the combustion was then 
examined, and was found to be pure carbo- 
nic acid, the same as that formed in the 
burning of charcoal; but what surprised 
Guyton was, the quantity produced was 
much greater than what would have been 
produced by the combustion of the same 
weight of charcoal in oxygen gas : 28 parts 
of charcoal form by combustion 100 parts 
of carbonic acid ; that is, combined with 72 
of oxygen ; but from only 17.8 of diamond, 
the same quantity of carbonic acid is pro- 
duced, that quantity having combined with 
82.1 of oxygen. In other words, 1 part of 
charcoal combines witli 2 of oxygen, form- 
ing of carbonic acid, while one part of 
diamond requires 4 of oxygen, and produces 
5 of acid. As the term carbon in the new 
nomenclature is understood to be applied 
to the simple base of carbonic acid, it is 
evident that it can no longer be applied to 
the inflammable matter of charcoal; for in 
that matter it must be combined with some 
other principle. Guyton supposes that this 
principle is oxygen, or, that that inflam- 
mable body is an oxide of carbon, standing 
in the same relation to carbon and carbonic 
acid that nitrous oxide does to nitrogen and 
nitric acid. Berthollet, on the contrary, 
has supposed that charcoal contains hydro- 
gen as a constituent part. Whichever of 
these opinions is adopted, the name carbon, 
it is obvious, must now be applied to the 
simple base, and will therefore be the che- 
mical or systematic term appropriated to 
the diamond. See Diamond. 
Besides charcoal and carborac acid, other 
substances have been discovered to be bi- 
nary compounds of carbon. The one known 
by the name of blaek-lead, or plumbago, 
approaches nearer to the diamond, or com- 
bines with more oxygen in forming carbonic 
acid than charcoal does ; and between char- 
coal and carbonic aeid is a gaseous cOm- 
CAR 
pound, into the composition of which oxy- 
gen enters, though it is still of the nature of 
an oxide. Carbon too combines with hy- 
drogen and oxygen, forming various elastic 
compounds. See Gas. 
CARBONATES, in chemistry, salts 
formed by a combination of the alkalies and 
the carbonic acid. As the acid powers 
which carbonic acid actually exerts are 
weak, the changes which it occasions in the 
properties of the alkalies are in general in- 
considerable. They retain their peculiar 
taste and acrimony, at least to a certain 
extent: ammonia has still its penetrating 
odour, and in part its volatility : they still, 
even when saturated with it, change the 
vegetable colours to a green. They com- 
bine with oils, forming imperfect soaps, and 
the presence of the carbonic acid scarcely 
opposes any obstacle to the combinations of 
their bases witli the other acids. 
CARBONIC acid, a gaseous product of 
the fiill saturation of carbon witli oxygen. 
It was made known to chemists by Dr. 
Black, under the name of fixed air, and 
may be regarded as the first of the aerial 
fluids that obtained accurate examination. 
It is composed of 75 parts of carbon, and 
25 of oxygen. See Gas. 
Carbonic oxide, in chemistry, a gas 
supposed to be compounded of carbon and 
oxygen, in the proportion of about 38 to 62. 
This gas possesses the mechanical properties 
of air. It burns with a deep blue flame, 
and gives out little light. See Gas. 
CARBUNCE, in heraldry, a charge or 
bearing, consisting of eight radii, four where- 
of make a common cross, and the other four 
a saltier. 
CARBURET, in chemistry, a compound 
substance, in which carbon is a constituent 
part. Carburet of iron, long known under 
the names of plumbago and black-lead, is 
compounded of 90 parts of carbon and 10 
of iron. It is found native, is of a dark grey 
or blue colour, and has something of a me- 
tallic lustre. It is found in many parts of 
the world, particularly in Cumberland. 
From' the substance obtained there the best 
black-lead pencils are manufactured. 
CARCASE, in architecture, the shell or 
ribs of a house, containing the partitions, 
floors, and rafters, made by carpenters ; or 
it is the timber-work (or as it were the ske- 
leton) of a house, before it is lathed and 
plastered: it is otherwise called the flam- 
ing. 
CARCASSE, or Carcuss, in the art of 
war, an iron-case or hollow capacity, about 
