hat extraordinary; but
this must be the case with all new terms, which cannot be expected to
become familiar until they have been some time in use. We long
endeavoured to find a more proper designation without success; it was at
first proposed to call it _alkaligen gas_, as, from the experiments of
Mr Berthollet, it appears to enter into the composition of ammoniac, or
volatile alkali; but then, we have as yet no proof of its making one of
the constituent elements of the other alkalies; beside, it is proved to
compose a part of the nitric acid, which gives as good reason to have
called it _nitrigen_. For these reasons, finding it necessary to reject
any name upon systematic principles, we have considered that we run no
risk of mistake in adopting the terms of _azote_, and _azotic gas_,
which only express a matter of fact, or that property which it
possesses, of depriving such animals as breathe it of their lives.

I should anticipate subjects more properly reserved for the subsequent
chapters, were I in this place to enter upon the nomenclature of the
several species of gasses: It is sufficient, in this part of the work,
to establish the principles upon which their denominations are founded.
The principal merit of the nomenclature we have adopted is, that, when
once the simple elementary substance is distinguished by an appropriate
term, the names of all its compounds derive readily, and necessarily,
from this first denomination.

FOOTNOTES:

[10] In English, the word _steam_ is exclusively appropriated to water
in the state of vapour. E.

CHAP. V.

_Of the Decomposition of Oxygen Gas by Sulphur, Phosphorus, and
Charcoal--and of the Formation of Acids in general._

In performing experiments, it is a necessary principle, which ought
never to be deviated from, that they be simplified as much as possible,
and that every circumstance capable of rendering their results
complicated be carefully removed. Wherefore, in the experiments which
form the object of this chapter, we have never employed atmospheric air,
which is not a simple substance. It is true, that the azotic gas, which
forms a part of its mixture, appears to be merely passive during
combustion and calcination; but, besides that it retards these
operations very considerably, we are not certain but it may even alter
their results in some circumstances; for which reason, I have thought it
necessary to remove even this possible cause of doubt, by only m