COMPOSITION OF VOLATILE ALKALI.
245
ment, produces the water which Dr. Priestley observed, and the hy
drogen disappeared. But, in the second experiment, the azote, which
is a simple substance, and muſt have existed in some of the ingredi
ents, but cannot be demonstrated in minium carefully prepared, must
have come from the ammonia, and muft have been one of its ingre
dients. The other is, in all probability, hydrogen ; for it is a simple
fubstance, and it is yielded by putrid muscle when digested with ni
tric acid; which putrid muſcle alfo yields volatile alkali. It yields
volatile alkali only when it ceaſes to yield difengaged azote, the putre
factive process having combined it with the hydrogen.
This is the general theory, founded on a very few experiments in
deed, but these abundantly simple. They are not, perhaps, decifive ;
but this theory gathers strength by attending to a number of more
complex facts, and taking along with us the two discoveries of Mr.
Cavendish, —the composition of water, and that of the nitrous acid, as
propositions fully demonstrated.
1. Our newspapers inform us that the French chemists procured
saltpetre for the army, by blowing alkaline gas, and even putrid
steams, through red hot substances which readily yield oxygen. We
know that such ſteams yield both inflammable air and azotic gas.
The laſt of these seizes part of the oxygen presented to it, and forms
nitrous acid, while another part combines with the inflammable air,
and composes water, which dilutes the acid. It seems to be for such
reasons that putrescent substances are useful in nitre beds, and that
the nitre first obtained is frequently nitrous ammoniac.
We often find the older chemifts exprefsing their surprise at the
ſtrong ſmell of volatile alkali from the mixture of substances which
contain none. Thus, iron or copper filings, when dissolved in strong
nitrous acid, often emit the ſmell of volatile alkali, instead of the of
fensive smell generally emitted from this mixture. The metal may
be supposed to decompose the water; and the hydrogen, uniting with
the azote (now redundant in the nitrous gas in consequence of the dis-
solution of some metal by the acid) will form ammonia.