lammable
air into a state in which it extinguishes candles, without any
intermediate state, in which it will admit a candle to burn in it, than
otherwise. This subject requires and deserves farther investigation. It
will also be well worth while to examine what difference the agitation
of air in natural or artificial _sea-water_ will occasion.

Since acid air and phlogiston make inflammable air, and since
inflammable air is convertible into air fit for respiration, it seems
not to be improbable, that these two ingredients are the only essential
principles of common air. For this change is produced by agitation in
water only, without the addition of any fixed air, though this kind of
air, like various other things of a foreign nature, may be combined with
it.

Considering also what prodigious quantities of inflammable air are
produced by the burning of small pieces of wood or pit-coal, it may not
be improbable but that the _volcanos_, with which there are evident
traces of almost the whole surface of the earth having been overspread,
may have been the origin of our atmosphere, as well as (according to the
opinion of some) of all the solid land.

The superfluous phlogiston of the air, in the state in which it issues
from volcanos, may have been imbibed by the waters of the sea, which it
is probable originally covered the surface of the earth, though part of
it might have united with the acid vapour exhaled from the sea, and by
this union have made a considerable and valuable addition to the common
mass of air; and the remainder of this over-charge of phlogiston may
have been imbibed by plants as soon as the earth was furnished with
them.

That an acid vapour is really exhaled from the sea, by the heat of the
sun, seems to be evident from the remarkably different states of the
atmosphere, in this respect, in hot and cold climates. In Hudson's bay,
and also in Russia, it is said, that metals hardly ever rust, whereas
they are remarkably liable to rust in Barbadoes, and other islands
between the tropics. See Ellis's Voyage, p. 288. This is also the case
in places abounding with salt-springs, as Nantwich in Cheshire.

That mild air should consist of parts of so very different a nature as
an acid vapour and phlogiston, one of which is so exceedingly corrosive,
will not appear surprising to a chemist, who considers the very strong
affinity which these two principles are known to have with each other,
and the exceedingly d