After this I permitted everything to cool,
and tied up the bladder. Lastly I removed it from the neck of the
retort. I filled a bottle, which contained 10 ounces of water, with this
gas (Sec. 30, _e._), I then placed a small lighted candle in it; scarcely
had this been done when the candle began to burn with a large flame,
whereby it gave out such a bright light that it was sufficient to dazzle
the eyes. I mixed one part of this air with three parts of that kind of
air in which fire would not burn; I had here an air which was like the
ordinary air in every respect. Since this air is necessarily required
for the origination of fire, and makes up about the third part of our
common air, I shall call it after this, for the sake of shortness,
Fire-air; but the other air which is not in the least serviceable for
the fiery phenomenon, and makes up about two-thirds of our air, I shall
designate after this with the name already known, of Vitiated Air.

+30.+ Anyone might ask me in what way I bring air from one vessel into
another. I find it necessary therefore to describe this in the first
place. My arrangements and vessels are the very simplest that one can
possibly have: flasks, retorts, bottles, glasses, and ox bladders are
the things which I employ. The bladders, while they are still fresh, are
rubbed, and blown up very fully, then tightly tied and hung up to dry.
When I wish to use such a bladder and find it blown up just as fully as
at first, I am thereby assured that it is tight.

(_a._) When I wish to collect any kind of air in a bladder, for example
the phlogisticated acid of nitre (Sec. 13), I take a soft bladder smeared
inside with a few drops of oil, and place in it some filings of a metal,
as iron, zinc, or tin; I then press the air as completely as possible
out of the bladder and tie it very tightly over a small bottle into
which some _aqua fortis_ has been poured; I then partly unfold the
bladder so that a few iron filings may fall into the _aqua fortis_,
according as this dissolves the bladder becomes expanded. When I have
collected enough of the air so produced, I tightly tie up the bladder
with a thread close above the mouth of the bottle, and then detach it
from the bottle. (_b._) If this phlogisticated acid of nitre is mixed
with aerial acid, which is the case when the acid of the nitre is
extracted over sugar, I tie a bladder, softened with some water, to the
extreme end of the neck of the retort A (Fig.