principles that are separated, instead of passing ¢ 
pear new modes and oe gp and form compot 
then become the products of the analysis. These cannot b 
bined again, or, if they could, they would form a compound te 
ly different from the substance originally analysed. "They ae 
however, be subjected to a further analysis, and thus the wignuee: 
principles of the compound may be accurately ascertained. The 
whole of the substances belonging to the vegetable and a 
doms are subject to this complicated analysis. 
In analysing the various products of nature, we ultimately arrive 
at a few substances which we are unable farther to decompose, and 
which are therefore regarded as simple. Their absolute” ity 
is not indeed established, but is in , till their composition b 
proved. They are simple with regard to ‘our present knowlege of 
them, that is, they consist of particles, which, so far as can be dis- 
covered, are similar to each other, and they are regarded as the ele- 
ments of which all other bodies are composed. It is sufficient to 
state their distinguishing characters, and the principal compounds 
which they form. 
The first order of these substances, those which seem best entitled 
to the character of simplicity, are the SIMPLE GASES, Oxygen, azot, 
and hydrogen. Modern chemistry has demonstrated, that these 
gases are solid substances, brought into the zrial form | ‘the 
tion of caloric. In the new nomenclature, therefore, th 2 
each is given to the base, and from this the appellation of the air or 
gas is derived. 
Of these simple bodies, ocycEn is the most important, since it is 
either capable of combining with, or forms a component part of the | 
greater number of the productions of nature. Like other gases, itis oe 
invisible, and permanently elastic ; its specific gravity is a little su- 
perior to that of atmospheric air. Its distinguishing characters are 
its capacity of supporting combustion and animal life. It is indeed 
the only substance that can support either of these processes, ee, * 
is absolutely necessary to enable them to be carried on. eg 
- The influence of this air in supporting combustion, is more part 
talasty to be assumed as its distinguishing chemical char: 
so many of the most important chemical agents are forme p 
Operation. It is proved by the most unequivocal exp 
combustion i is nothing more than the combination of oxygen with 
body. Burnt bodies are therefore merely substan- 
combined with oxygen: that principle is contained in them in 
very various apmeatisiee, and is retained by-very different degrees of 
attractive force. 
Many substaneeaase algo be éombined with oxygen, without the 
© phenomena of combustion taking place, that.is, without the disen- aoe 
gagement of light and caloric. ‘This happens when the oxygen ies ie 
~ been previously combined with another body, and is only trans 1 
from it by the exertion of a superior affinity. It happens, too, 
‘when the oxygen is slowly absorbed from the atmosphere, at the 
_‘Ratural temperature. It is thus that many animal and veget 
a ad axperire to the | air. The absor} 
oe met 
* 
