e to recover
persons from swooning. A bit of spunge, about as big as a hazel nut,
presently imbibed an ounce measure of alkaline air.

A piece of the inspissated juice of _turnsole_ was made very dry and
warm, and yet it imbibed a great quantity of the air; by which it
contracted a most pungent smell, but the colour of it was not changed.

_Alum_ undergoes a very remarkable change by the action of alkaline air.
The outward shape and size remain the same, but the internal structure
is quite changed, becoming opaque, beautifully white, and, to
appearance, in all respects, like alum which had been roasted; and so as
not to be at all affected by a degree of heat that would have reduced it
to that state by roasting. This effect is produced slowly; and if a
piece of alum be taken out of alkaline air before the operation is over,
the inside will be transparent, and the outside, to an equal thickness,
will be a white crust.

I imagine that the alkaline vapour seizes upon the water that enters
into the constitution of crude alum, and which would have been expelled
by heat. Roasted alum also imbibes alkaline air, and, like the raw alum
that has been exposed to it, acquires a taste that is peculiarly
disagreeable.

_Phosphorus_ gave no light in alkaline air, and made no lasting change
in its dimensions. It varied, indeed, a little, being sometimes
increased and sometimes diminished, but after a day and a night, it was
in the same state as at the first. Water absorbed this air just as if
nothing had been put to it.

Having put some _spirit of salt_ to alkaline air, the air was presently
absorbed, and a little of the white salt above-mentioned was formed. A
little remained unabsorbed, and transparent, but upon the admission of
common air to it, it instantly became white.

_Oil of vitriol_, also formed a white salt with alkaline air, and this
did not rise in white fumes.

Acid air, as I have observed in my former papers, extinguishes a candle.
Alkaline air, on the contrary, I was surprized to find, is slightly
inflammable; which, however, seems to confirm the opinion of chemists,
that the volatile alkali contains phlogiston.

I dipped a lighted candle into a tall cylindrical vessel, filled with
alkaline air, when it went out three or four times successively; but at
each time the flame was considerably enlarged, by the addition of
another flame, of a pale yellow colour; and at the last time this light
flame descended from th