trefaction, should yield
so great a quantity of inflammable air, as the dried animal substance
would have done. Of this I have not made an actual trial, though I have
often thought of doing it, and still intend to do it; but I think there
can be no doubt of the result.

Again, iron, by its fermentation with brimstone and water, is evidently
reduced to a calx, so that phlogiston must have escaped from it.
Phlogiston also must evidently be set loose by the ignition of charcoal,
and is not improbably the matter which flies off from paint, composed of
white-lead and oil. Lastly, since spirit of nitre is known to have a
very remarkable affinity with phlogiston, it is far from being
improbable that nitrous air may also produce the same effect by the same
means.

To this hypothesis it may be objected, that, if diminished air be air
saturated with phlogiston, it ought to be inflammable. But this by no
means follows; since its inflammability may depend upon some particular
_mode of combination_, or degree of affinity, with which we are not
acquainted. Besides, inflammable air seems to consist of some other
principle, or to have some other constituent part, besides phlogiston
and common air, as is probable from that remarkable deposit, which, as I
have observed, is made by inflammable air, both from iron and zinc.

It is not improbable, however, but that a greater degree of heat may
inflame that air which extinguishes a common candle, if it could be
conveniently applied. Air that is inflammable, I observe, extinguishes
red-hot wood; and indeed inflammable substances can only be those which,
in a certain degree of heat, have a less affinity with the phlogiston
they contain, than the air, or some other contiguous substance, has with
it; so that the phlogiston only quits one substance, with which it was
before combined, and enters another, with which it may be combined in a
very different manner. This substance, however, whether it be air or any
thing else, being now fully saturated with phlogiston, and not being
able to take any more, in the same circumstances, must necessarily
extinguish fire, and put a stop to the ignition of all other bodies,
that is, to the farther escape of phlogiston from them.

That plants restore noxious air, by imbibing the phlogiston with which
it is loaded, is very agreeable to the conjectures of Dr. Franklin,
made many years ago, and expressed in the following extract from the
last edition of his Le