of two parts, by weight, of oxygen combined with one part of
azote; and in this state it is not miscible with water. In this gas, the
azote is by no means saturated with oxygen, but, on the contrary, has
still a very great affinity for that element, and even attracts it from
atmospheric air, immediately upon getting into contact with it. This
combination of nitrous gas with atmospheric air has even become one of
the methods for determining the quantity of oxygen contained in air, and
consequently for ascertaining its degree of salubrity.

This addition of oxygen converts the nitrous gas into a powerful acid,
which has a strong affinity with water, and which is itself susceptible
of various additional degrees of oxygenation. When the proportions of
oxygen and azote is below three parts, by weight, of the former, to one
of the latter, the acid is red coloured, and emits copious fumes. In
this state, by the application of a gentle heat, it gives out nitrous
gas; and we term it, in this degree of oxygenation, _nitrous acid_. When
four parts, by weight, of oxygen, are combined with one part of azote,
the acid is clear and colourless, more fixed in the fire than the
nitrous acid, has less odour, and its constituent elements are more
firmly united. This species of acid, in conformity with our principles
of nomenclature, is called _nitric acid_.

Thus, nitric acid is the acid of nitre, surcharged with oxygen; nitrous
acid is the acid of nitre surcharged with azote; or, what is the same
thing, with nitrous gas; and this latter is azote not sufficiently
saturated with oxygen to possess the properties of an acid. To this
degree of oxygenation, we have afterwards, in the course of this work,
given the generical name of _oxyd_[14].

FOOTNOTES:

[12] The term formerly used by the English chemists for this acid was
written _sulphureous_; but we have thought proper to spell it as above,
that it may better conform with the similar terminations of nitrous,
carbonous, &c. to be used hereafter. In general, we have used the
English terminations _ic_ and _ous_ to translate the terms of the Author
which end with _ique_ and _cux_, with hardly any other alterations.--E.

[13] For this purpose, the operation called _decrepitation_ is used,
which consists in subjecting it to nearly a red heat, in a proper
vessel, so as to evaporate all its water of crystallization.--E.

[14] In strict conformity with the principles of the new nomenclature,