: 
=e 
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On definite Proportions. 463 
trogen gas in a state of perfect purity. The acid and the 
alkali afford equal quantities of nitrogen, but the alkali con- 
tains half as much more ammonium as the acid. When 
the dry salt is heated, and then produces, as we have seen, 
very different substances, the process may be thus explained 
the nitrite of ammonia is decomposed on one hand, like the 
nitrite of the protoxide of lead, into nitrous gas, nitrate of 
ammonia, and uncombined ammonia, since this alkali 
affords no subsalt; and on the other hand another part of 
the alkali is resolved into water and nitrogen; and since 
the nitrous gas and the nitrogen are in contact at the instant 
of their formation, they unite, and constitute nitrous oxide ; 
so that the products of this twofold decomposition are ni- 
trous oxide, water, uncombined ammonia, and nitrate of 
ammonia, which, being further decomposed, augments the 
quantity of the nitrous oxide and of the water. 
I believe that these experiments are sufficient in the first 
place to illustrate more fully the doctrine of the composition 
of the nitric acid; and secondly, to show that the nitrous 
acid is a distinct acid, producing peculiar salts with different 
bases, and neutralising such a quantity of them as contains 
4as much oxygen as itself. Some modern chemists had 
been disposed to consider this acid as a compound of nitric 
acid with nitrous gas, which was destroyed by the com- 
bination of the acid with a base. This opinion was how- 
ever founded on experiments which by no means justified 
the inference drawn from them. 
The knowledge of the nitrites is indispensable to the ex- 
planation of some appearances which the nitric acid exhi- 
bits. It is wel] known, for example, that diluted nitric acid, 
formed from concentrated colourless acid, 1s a much less 
powerful solvent of many metals than that which is made 
from the smoking acid. If the smoking nitric acid were 
nothing more than a solution of nitrous gas in nitric acid, 
it would be inconceivable, bow the nitrous gas could be su 
efficacious, as it cannot be decomposed by the bodies to be 
dissolved. Since however we know that the nitrous acid is 
a.peculiar acid, which is more easily decomposed than the 
nitric, there is no longer any thing paradoxical in the su- 
wry efficacy of the solvent made by diluting the smoking 
acid, 
[End of the Seconp ConTINUATION.] 
. LXXY. Final 
