hen approached a burning candle to the orifice
of the tube, whereupon the inflammable air took fire and burned with a
small yellowish-green flame. As soon as this had taken place, I took a
small flask C, which was capable of holding 20 ounces of water, and held
it so deep in the water that the little flame stood in the middle of the
flask. The water at once began to rise gradually into the flask, and
when the level had reached the point D the flame went out. Immediately
afterwards the water began to sink again, and was entirely driven out of
the flask. The space in the flask up to D contained 4 ounces, therefore
the fifth part of the air had been lost. I poured a few ounces of lime
water into the flask in order to see whether any aerial acid had also
been produced during the combustion, but I did not find any. I made the
same experiment with zinc filings, and it proceeded in every way
similarly to that just mentioned. I shall demonstrate the constituents
of this inflammable air further on; for, although it seems to follow
from these experiments that it is only phlogiston, still other
experiments are contrary to this.

We shall now see the behaviour of air towards that kind of fire which
gives off, during the combustion, a fluid resembling air.

[Illustration: _Fig. 1._]

[Illustration: _Fig. 2._]

[Illustration: _Fig. 3._]

[Illustration: _Fig. 4._]

[Illustration: _Fig. 5._]

+20. Fourth Experiment.+--It is well known that the flame of a candle
absorbs air; but as it is very difficult, and, indeed, scarcely
possible, to light a candle in a closed flask, the following experiment
was made in the first place:--I set a burning candle in a dish full
water; I then placed an inverted flask over this candle; at once there
arose from the water large air bubbles, which were caused by the
expansion, by heat, of the air in the flask. When the flame became
somewhat smaller, the water began to rise in the flask; after it had
gone out and the flask had become cold, I found the fourth part filled
with water. This experiment was very undecisive to me, because I was not
assured whether this fourth part of the air had not been driven out by
the heat of the flame; since necessarily in that case the external air
resting upon the water seeks equilibrium again after the flask has
become cold, and presses the same measure of water into the flask as of
air had been previously driven out by the heat. Accordingly, I made the
following