a jar full of quicksilver, I was able to procure
little or nothing.

It is not a little remarkable that nitrous air diminished by iron
filings and brimstone, which is about one fourth, cannot, by agitation
in water, be diminished much farther; whereas pure nitrous air may, by
the same process, be diminished to one twentieth of its whole bulk, and
perhaps much more. This is similar to the effect of the same mixture,
and of phlogiston in other cases, on fixed air; for it so far changes
its constitution, that it is afterwards incapable of mixing with water.
It is similar also to the effect of phlogiston in acid air, which of
itself is almost instantly absorbed by water; but by this addition it is
first converted into inflammable air, which does not readily mix with
water, and which, by long agitation in water, becomes of another
constitution, still less miscible with water.

I shall close this section with a few other observations of a
miscellaneous nature.

Nitrous air is as much diminished both by iron filings, and also by
liver of sulphur, when confined in quicksilver, as when it is exposed to
water.

Distilled water tinged blue with the juice of turnsole becomes red on
being impregnated with nitrous air; but by being exposed a week or a
fortnight to the common atmosphere, in open and shallow vessels, it
recovers its blue colour; though, in that time, the greater part of the
water will be evaporated. This shews that in time nitrous air escapes
from the water with which it is combined, just as fixed air does, though
by no means so readily[14].

Having dissolved silver, copper, and iron in equal quantities of spirit
of nitre diluted with water, the quantities of nitrous air produced from
them were in the following proportion; from iron 8, from copper 6-1/4,
from silver 6. In about the same proportion also it was necessary to
mix water with the spirit of nitre in each case, in order to make it
dissolve these metals with equal rapidity, silver requiring the least
water, and iron the most.

Phosphorus gave no light in nitrous air, and did not take away from its
power of diminishing common air; only when the redness of the mixture
went off, the vessel in which it was made was filled with white fumes,
as if there had been some volatile alkali in it. The phosphorus itself
was unchanged.

There is something remarkable in the effect of nitrous air on _insects_
that are put into it. I observed before that this kind of air