inflammable and common air. At another time, however, I could
not procure any inflammable air by this means, but to what circumstance
these different results were owing I cannot tell.

That inflammable air is produced from _charcoal_ in acid air I observed
before. I have since found that it may likewise be procured from _pit
coal_, without being charred.

Inflammable air I had also observed to arise from the exposure of spirit
of wine, and various _oily_ substances, to the vapour of spirit of salt.
I have since made others of a similar nature, and as peculiar
circumstances attended some of these experiments, I shall recite them
more at large.

_Essential oil of mint_ absorbed this air pretty fast, and presently
became of a deep brown colour. When it was taken out of this air it was
of the consistence of treacle, and sunk in water, smelling differently
from what it did before; but still the smell of the mint was
predominant. Very little or none of the air was fixed, so as to become
inflammable; but more time would probably have produced this effect.

_Oil of turpentine_ was also much thickened, and became of a deep brown
colour, by being saturated with acid air.

_Ether_ absorbed acid air very fast, and became first of a turbid white,
and then of a yellow and brown colour. In one night a considerable
quantity of permanent air was produced, and it was strongly inflammable.

Having, at one time, fully saturated a quantity of ether with acid air,
I admitted bubbles of common air to it, through the quicksilver, by
which it was confined, and observed that white fumes were made in it, at
the entrance of every bubble, for a considerable time.

At another time, having fully saturated a small quantity of ether with
acid air, and having left the phial in which it was contained nearly
full of the air, and inverted, it was by some accident overturned; when,
instantly, the whole room was filled with a visible fume, like a white
cloud, which had very much the smell of ether, but peculiarly offensive.
Opening the door and window of the room, this light cloud filled a long
passage, and another room. In the mean time the ether was seemingly all
vanished, but some time after the surface of the quicksilver in which
the experiment had been made was covered with a liquor that tasted very
acid; arising, probably, from the moisture in the atmosphere attracted
by the acid vapour with which the ether had been impregnated.

This visible c