ON CHEMISTRY. 
437 
but hydrogen gas, is an aeriform fluid, the lightest known matter, 
perhaps, of all things that possess weight. It is usually said to be a 
compound of the base, and a certain definite proportion of caloric, or 
the matter of heat. My hypothesis, or the electric hypothesis, de¬ 
scribes it as a solid base, electro-chemically united with a definite 
proportion of solar etherial fire, by which its particles are extended 
and divided, not, however, intersticially, by an act of propulsion or 
separation, but by a specific, chemical action, whereby each particle 
occupies a certain and vastly enlarged space, but still is identical in 
its nature, a pure chemical compound of the base and of its subtile, 
all-pervading solvent. 
Carbon , derived from the Latin word carbo , burnt wood, or char¬ 
coal, is that peculiar substance familiarly known as the product of 
the slow combustion of wood. This explanation is not, however, 
strictly correct, for charcoal is not pure carbon, since it is found to 
contain a very large portion of oxygen and other foreign matters, to 
the extent, perhaps, of nearly one-third. Pure carbon is not to be 
found in any product of combustion, nor throughout nature unless it 
be in the diamond. It is said, however, to exist, ready formed, in 
vegetables; but to obtain it, chemists are obliged to “subject them to x 
the action of fire, at first moderate, and afterwards very strong, to 
drive oflf the last portions of water, which adhere very obstinately.” 
The reader is requested to notice this extract from Lavoisier; and 
to remark that the ready formed charcoal of vegetable substances is 
only to be detected by the operation of fire. The fact thus laid bare 
will lead to very important results, as it will be my endeavour to 
prove hereafter. I now content myself by observing, that the sub¬ 
stance generally understood by the term carbon is charcoal, a pro¬ 
duct of combustion that contains a portion of oxygen; a further 
dose of which converts the charcoal into an elastic gaseous fluid called 
carbonic acid. Pure carbon has never yet been decomposed, it is 
therefore considered a simple elementary substance, and unless the 
diamond be its type, it has not as yet been discovered in a free, un¬ 
combined state. 
Azof or Nitrogen is one of the constituents of atmospheric air, and 
also of the nitric and nitrous acid. The former term is derived from 
the Greek privative letter or particle, a, implying a destruction or 
deprivation of, and (Zoe) life, and the latter from nr^ov (nitron 
whence nitrum Latin) nitre, or nitrate of potasse, saltpetre ; and 
yam I generate, before described. Nitrogen, or nitrigen, expresses 
a product from nitre, or rather nitric acid ; because this peculiar gas 
may be procured by the decomposition of that acid. It is a curious 
