Part 10 (1/2)

Having satisfied myself with respect to the relation that alkaline air bears to water, I was impatient to find what would be the consequence of mixing this new air with the other kinds with which I was acquainted before, and especially with _acid_ air; having a notion that these two airs, being of opposite natures, might compose a _neutral air_, and perhaps the very same thing with common air. But the moment that these two kinds of air came into contact, a beautiful white cloud was formed, and presently filled the whole vessel in which they were contained. At the same time the quant.i.ty of air began to diminish, and, at length, when the cloud was subsided, there appeared to be formed a solid _while salt_, which was found to be the common _sal ammoniac_, or the marine acid united to the volatile alkali.

The first quant.i.ty that I produced immediately deliquesced, upon being exposed to the common air; but if it was exposed in a very dry and warm place, it almost all evaporated, in a white cloud. I have, however, since, from the same materials, produced the salt above-mentioned in a state not subject to deliquesce or evaporate. This difference, I find, is owing to the proportion of the two kinds of air in the compound. It is only volatile when there is more than a due proportion of either of the const.i.tuent parts. In these cases the smell of the salts is extremely pungent, but very different from one another; being manifestly acid, or alkaline, according to the prevalence of each of these airs respectively.

_Nitrous air_ admitted to alkaline air likewise occasioned a whitish cloud, and part of the air was absorbed; but it presently grew clear again; leaving only a little dimness on the sides of the vessel. This, however, might be a kind of salt, formed by the union of the two kinds of air. There was no other salt formed that I could perceive. Water being admitted to this mixture of nitrous and alkaline air presently absorbed the latter, and left the former possessed of its peculiar properties.

_Fixed air_ admitted to alkaline air formed oblong and slender crystals, which crossed one another, and covered the sides of the vessel in the form of net-work. These crystals must be the same thing with the volatile alkalis which chemists get in a solid form, by the distillation of sal ammoniac with fixed alkaline salts.

_Inflammable air_ admitted to alkaline air exhibited no particular appearance. Water, as in the former experiment, absorbed the alkaline air, and left the inflammable air as it was before. It was remarkable, however, that the water which was admitted to them became whitish, and that this white cloud settled, in the form of a white powder, to the bottom of the vessel.

Alkaline air mixed with _common air_, and standing together several days, first in quicksilver, and then in water (which absorbed the alkaline air) it did not appear that there was any change produced in the common air: at least it was as much diminished by nitrous air as before. The same was the case with a mixture of acid air and common air.

Having mixed air that had been diminished by the fermentation of a mixture of iron filings and brimstone with alkaline air, the water absorbed the latter, but left the former, with respect to the test of nitrous air (and therefore, as I conclude, with respect to all its properties) the same that it was before.

_Spirit of wine_ imbibes alkaline air as readily as water, and seems to be as inflammable afterwards as before.

Alkaline air contracts no union with _olive oil_. They were in contact almost two days, without any diminution of the air. Oil of turpentine, and essential oil of mint, absorbed a very small quant.i.ty of alkaline air, but were not sensibly changed by it.

_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 circ.u.mstance 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 insp.i.s.sated juice of _turnsole_ was made very dry and warm, and yet it imbibed a great quant.i.ty 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 const.i.tution 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 the top of the vessel to the bottom. At another time, upon presenting a lighted candle to the mouth of the same vessel, filled with the same kind of air, the yellowish flame ascended two inches higher than the flame of the candle. The electric spark taken in alkaline air is red, as it is in common inflammable air.

Though alkaline air be inflammable, it appeared, by the following experiment, to be heavier than the common inflammable air, as well as to contract no union with it. Into a vessel containing a quant.i.ty of inflammable air, I put half as much alkaline air, and then about the same quant.i.ty of acid air. These immediately formed a white cloud, but it did not rise within the s.p.a.ce that was occupied by the inflammable air; so that this latter had kept its place above the alkaline air, and had not mixed with it.

That alkaline air is lighter than acid air is evident from the appearances that attend the mixture, which are indeed very beautiful.

When acid air is introduced into a vessel containing alkaline air, the white cloud which they form appears at the bottom only, and ascends gradually. But when the alkaline air is put to the acid, the whole becomes immediately cloudy, quite to the top of the vessel.

In the last place, I shall observe that alkaline air, as well as acid, dissolves _ice_ as fast as a hot fire can do it. This was tried when both the kinds of air, and every instrument made use of in the experiment, had been exposed to a pretty intense frost several hours. In both cases, also, the water into which the ice was melted dissolved more ice, to a considerable quant.i.ty.

SECTION II.

_Of COMMON AIR diminished and made noxious by various processes._