_Ether_, however, imbibed alkaline air pretty freely; but it was afterwards as inflammable as before, and the colour was not changed. It also evaporated as before, but I did not attend to this last circumstance very accurately. _Sulphur_, _nitre_, _common salt_, and _flints_, were put to alkaline air without imbibing any part of it; but _charcoal_, _spunge_, bits of _linen cloth_, and other substances of that nature, seemed to condense this air upon their surfaces; for it began to diminish immediately upon their being put to it; and when they were taken out the alkaline smell they had contracted was so pungent as to be almost intolerable, especially that of the spunge. Perhaps it might be of use 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.