1817] Axote and Oxygen. 191 
They both conclude that nitrous gas is composed of equal volumes 
of azote and oxygen; this agrees with the modern specific gravity 
of nitrous gas determined since the theory of volumes was an- 
nounced, but not with the previous one as found by the experiments 
of Kirwan and Davy: it certainly would be desirable to have the 
specific gravity of nitrous gas ascertained without any view to 
theory. 
In the present year (1816) Gay-Lussac has published in the Ann. 
de Chim. another essay on the compounds of azote and oxygen- 
In this new essay he has abandoned both his former maximum and 
minimum of nitrous gas uniting to oxygen, namely, two measures 
and three measures, as well as his eudiometer; and it would have 
been satisfactory if he had given some. reasons for his being so far 
misled in regard to phenomena so generally known and received. 
He now admits the minimum of nitrous gas to be 14 measure for 
one of oxygen, the same as Davy acknowledges, and nearly the 
same as | announced in 1810; but the maximum, he contends, 
instead of being three measures to one, as he formerly held, or 3°6 
as I maintained, is precisely four measures. He follows Davy in 
adopting the compound of one oxygen and 1 nitrous gas as con- 
stituting nitric acid ; one oxygen and two nitrous as nitrous acid 
gas: but he adds that one oxygen and four nitrous gas form a com- 
pound which he denominates pernitrous acid, and supposes it has 
never been noticed by any author before; though I had given a 
figure of it six years ago, under the denomination of nitrous acid 
(Chemistry, Plate V. No. 45); and had pointed out distinctly the 
method of obtaining it in a state of purity (p. 366). In acknow- 
ledging his own error in regard to the proportions of nitric acid, he 
properly adverts to a similar one of mine: in fact, we erred nearly 
in the same degree in regard to the proportions for nitric acid, 
having both of us mistaken nitrous for nitric acid; but he is incor- 
rect in the observation that my oxynitric acid is in reality the 
common nitric acid. ‘The oxynitric acid, the existence of which I 
inferred, consisted of one atom azote and three oxygen}; or it con- 
sisted of 80 per cent. oxygen by weight: whereas nitric acid, ac- 
cording to Gay-Lussac, contains only 74 per cent. of oxygen, and 
consists of two atoms or measures of azote and five oxygen. My 
oxynitric acid is quite different, therefore, from nitric acid, and the 
necessity of supposing such a compound as oxynitric acid is now 
superseded by the new view of the constitution of nitric acid. 
Since my last publication | have frequently recurred to the sub- 
ject of nitric acid, as well as to the other compounds of azote and 
oxygen; and about two years ago | became convinced that what I 
had called and figured as nitric acid was in reality nitrous acid gus, 
and that nitric acid is constituted of two atoms of this last con- 
nected by one of oxygen, and is formed by uniting one measure of 
oxygen to 12 of nitrous gas. The weight of an atom of nitric acid 
is, therefore, L apprehend, 45, and not 38 (the double of 19), as 
accounted in my Chemistry. Conformably with this idea, I fur- 
