n, which surprised me not a little;
though this corresponds in some measure, to the effect of phlogiston
exhaled from this substance on acid air. Perhaps more time may be
requisite for this purpose, for this process was not continued more than
a day and a night.

Iron filings and brimstone, I have observed, ferment with great heat in
nitrous air, and I have since observed that this process is attended
with greater heat in fixed air than in common air.

Though fixed air incorporated with water dissolves iron, fixed air
without water has no such power, as I observed before. I imagined that,
if it could have dissolved iron, the phlogiston would have united with
the air, and have made it immiscible with water, as in the former
instances; but after being confined in a phial full of nails from the
15th of December to the 4th of October following, neither the iron nor
the air appeared to have been affected by their mutual contact.

Having exposed equal quantities of common and fixed air, in equal and
similar cylindrical glass vessels, to equal degrees of heat, by placing
them before a fire, and frequently changing their situations, I observed
that they were expanded exactly alike, and when removed from the fire
they both recovered their former dimensions.

Having had some small suspicion that liver of sulphur, besides emitting
phlogiston, might also yield some fixed air (which is known to be
contained in the salt of tartar from which it is made) I mixed the two
ingredients, viz. salt of tartar and brimstone, and putting them into a
thin phial, and applying the flame of a candle to it, so as to form the
liver of sulphur, I received the air that came from it in this process
in a vessel of quicksilver. In this manner I procured a very
considerable quantity of fixed air, so that I judged it was all
discharged from the tartar. But though it is possible that a small
quantity of it may remain in liver of sulphur, when it is made in the
most perfect manner, it is not probable that it can be expelled without
heat.

SECTION VII.

MISCELLANEOUS EXPERIMENTS.

1. It is something extraordinary that, though ether, as I found, cannot
be made to assume the form of air (the vapour arising from it by heat,
being soon condensed by cold, even in quicksilver) yet that a very small
quantity of ether put to any kind of air, except the acid, and alkaline,
which it imbibes, almost instantly doubles the apparent quantity of it;
but upon