elf farther, that the bladder had produced this
effect, I put one into a jar of nitrous air, and after it had continued
there a day and a night, I found that the nitrous air in this jar,
though it was transferred in a glass vessel, made lime-water turbid.

Whether there was any thing in the preparation of these bladders that
occasioned their producing this effect, I cannot tell. They were such as
I procure from the apothecaries. The thing seems to deserve farther
examination, as there seems, in this case, to be the peculiar effect of
fixed air from other causes, or else a production of fixed air from
materials that have not been supposed to yield it, at least not in
circumstances similar to these.

As fixed air united to water dissolves iron, I had the curiosity to try
whether fixed air alone would do it; and as nitrous air is of an _acid_
nature, as well as fixed air, I, at the same time, exposed a large
surface of iron to both the kinds; first filling two eight ounce phials
with nails, and then with quicksilver, and after that displacing the
quicksilver in one of the phials by fixed air, and in the other by
nitrous air; then inverting them, and leaving them with their mouths
immersed in basons of quicksilver.

In these circumstances the two phials stood about two months, when no
sensible change at all was produced in the fixed air, or in the iron
which had been exposed to it, but a most remarkable, and most unexpected
change was made in the nitrous air; and in pursuing the experiment, it
was transformed into a species of air, with properties which, at the
time of my first publication on this subject, I should not have
hesitated to pronounce impossible, viz. air in which a candle burns
quite naturally and freely, and which is yet in the highest degree
noxious to animals, insomuch that they die the moment they are put into
it; whereas, in general, animals live with little sensible inconvenience
in air in which candles have burned out. Such, however, is nitrous air,
after it has been long exposed to a large surface of iron.

It is not less extraordinary, that a still longer continuance of nitrous
air in these circumstances (but _how long_ depends upon too many, and
too minute circumstances to be ascertained with exactness) makes it not
only to admit a candle to burn in it, but enables it to burn with an
_enlarged flame_, by another flame (extending every where to an equal
distance from that of the candle, and often pl