e inflammable air of all its inflammability, and this I
found to be the case; for, after a longer agitation, it admitted a
candle to burn in it, like common air, only more faintly; and indeed by
the test of nitrous air it did not appear to be near so good as common
air. Continuing the same process still farther, the air which had been
most strongly inflammable a little before, came to extinguish a candle,
exactly like air in which a candle had burned out, nor could they be
distinguished by the test of nitrous air.

I found, by repeated trials, that it was difficult to catch the time in
which inflammable air obtained from metals, in coming to extinguish
flame, was in the state of common air, so that the transition from the
one to the other must be very short. Indeed I think that in many,
perhaps in most cases, there may be no proper medium at all, the
phlogiston passing at once from that mode of union with its base which
constitutes inflammable air, to that which constitutes an air that
extinguishes flame, being so much overloaded as to admit of no more. I
readily, however, found this middle state in a quantity of inflammable
air extracted from oak, which air I had kept a year, and in which a
plant had grown, though very poorly, for some part of the time. A
quantity of this air, after being agitated in water till it was
diminished about one half, admitted a candle to burn in it exceedingly
well, and was even hardly to be distinguished from common air by the
test of nitrous air.

I took some pains to ascertain the quantity of diminution, in fresh made
and very highly-inflammable air from iron, at which it ceased to be
inflammable, and, upon the whole, I concluded that it was so when it was
diminished a little more than one half; for a quantity which was
diminished exactly one half had something inflammable in it, but in the
slightest degree imaginable. It is not improbable, however, but there
may be great differences in the result of this experiment.

Finding that water would imbibe inflammable air, I endeavoured to
impregnate water with it, by the same process by which I had made water
imbibe fixed air; but though I found that distilled water would imbibe
about one fourteenth of its bulk of inflammable air, I could not
perceive that the taste of it was sensibly altered.

FOOTNOTES:

[4] To try this, after every explosion, which immediately follows the
presenting of the flame, the mouth of the phial should be closed