made the experiments.
Having neglected these two jars of air, the plants died and putrefied in
both of them; and then I found the air in them both to be highly
noxious, and to make no effervescence with nitrous air.

I found that a pint of my pump-water contained about one fourth of an
ounce measure of air, one half of which was afterwards absorbed by
standing in fresh pump-water. A candle would not burn in this air, but a
mouse lived in it very well. Upon the whole, it seemed to be in about
the same state as air in which a candle had burned out.

6. I once imagined that, by mere _stagnation_, air might become unfit
for respiration, or at least the burning of candles; but if this be the
case, and the change be produced gradually, it must require a long time
for the purpose. For on the 22d of September 1772, I examined a quantity
of common air, which had been kept in a phial, without agitation, from
May 1771, and found it to be in no respect worse than fresh air, even by
the test of the nitrous air.

7. The crystallization of nitre makes no sensible alteration in the air
in which the process is made. For this purpose I dissolved as much nitre
as a quantity of hot water would contain, and let it cool under a
receiver, standing in water.

8. November 6, 1772, a quantity of inflammable air, which, by long
keeping, had come to extinguish flame, I observed to smell very much
like common air in which a mixture of iron filings and brimstone had
stood. It was not, however, quite so strong, but it was equally noxious.

9. Bismuth and nickel are dissolved in the marine acid with the
application of a considerable degree of heat; but little or no air is
got from either of them; but, what I thought a little remarkable, both
of them smelled very much like Harrowgate water, or liver of sulphur.
This smell I have met with several times in the course of my
experiments, and in processes very different from one another.

FOOTNOTES:

[10] Experiments, of which an account will be given in the second part
of this work, make it probable, that though a candle burned even _more
than well_ in this air, an animal would not have lived in it. At the
time of this first publication, however, I had no idea of this being
possible in nature.

PART II.

_Experiments and Observations made in the Year 1773, and the Beginning
of 1774._

SECTION I.

_Observations on ALKALINE AIR._

After I had made the discovery of the _marine a