acids are very easily decomposed, and hence are often em 
chemical operations to afford oxygen to other bodies. With smaller 
proportions of oxygen, it forms two gases, neither of which has acid 
properties; nitrous gas, com d of 44 of azot with 56 of oxygen, | 
-distinguished by the facility vith which it unites with an additional 
proportion of oxygen ; and nitrous oxyd, consisting of 63 of azot, 
and 37 of oxygen, peculiarly characterized by its high exhila- 
rating powers on the animal system. Combined with hydrogen, in 
the proportion of #21 parts to 32, it forms ammonia, or volatile 
alkali, and hence it has been supposed, from analogy, that the other 
two alkalies also contain azot as a constituent principle. . ne 
Lastly, azot is contained in great abundance in animal r rs, 
and is the principle which distinguishes them, by their chemical 
composition, from vegetables. api: 
The last of these simple airs is uyproceN. It is the lightest of 
all the gases, its specific gravity, when it is in its purest state, being 
to that of atmospheric air as13to 1. Itis highly inflammable ; one 
part of it mixed with four parts of atmospheric air, exploding with 
violence on the approach of an ignited body. 
The most important compound of hydrogen is water, formed by 
its union with oxygen, in the proportion of 15 parts, by weight, of 
the former, to 85 of the latter. Asa chemical agent, water is of the 
first importance, both from its very extensive power of comb: 
and from its agency im affording oxygen. ‘It is the solvent of 
saline, and of the greater number of the earthy substances ; and it 
likewise dissolves a number of the vegetable and animal products. 
In these combinations, it is singular that the general law of chemi- 
cal attraction, (that combination which alters the properties of bo- 
dies,) is scarcely observed ; the properties of the bodies dissolved by 
water remaining almost invariably nearly the same, and that fluidity 
being merely communicated to them which is necessary for their 
mutual chemical action, or which renders convenient their prepara- 
tion as medicines. 
Water is farther an ‘important chemical agent, by affording oxy- 
gen to a number of bodies. ‘Thus, many of the metals are slowly 
oxydated by it ; and in their solutions by acids; it is frequently from — 
the water that the metal receives oxygen. The vegetable and ani- 
mal products receive oxygen also from the water they contain ; and — 
in the decompositions which they suffer, whether from the reaction of 
their principles at a natural temperature, or by exposure to heat, the 
elements of the water present enter into the composition of the pro- 
ducts which such analysis afford. , 
Under the appellation of srmpie INFLAMMABLE SUBSTANCES, are 
commonly described three bodies, carbon, sulphur, and phosphorus. 
They exist in the solid form, but are totally destitute of the metallic 
Splendor, opacity and gravity. They are highly inflammable, and 
form acids when united with oxygen. - i 
_ Carson, the first of these, is an inflammable matter, the ba 
mmon charcoal. In this substance, it was supposed to be me 
oxyd of iron, and some other impurities But the expe 
ton have proved that ‘iit is also combined with a p 
newt 
es 
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