mon spirit of falt might have the fame effect,

but it had not.

For this purpose I treated the

fpirit of falt, as I had before done the fmoking spirit of nitre; first filling a phial with it, then inverting it in a veffel containing a quantity of the fame acid and having thrown the inflammable air into it, and thereby driven out all the acid, turning it with its mouth upwards, and immediately applying a candle to it.

Acid air not being fo manageable as most of the other kinds of air, I had recourfe to the following peculiar method, in order to afcertain its Specific gravity. Having filled an eight ounce phial with this air, and corked it up, I weighed it very accurately; and then, taking out the cork, I blew very strongly into it with a pair of bellows, that the common air might take place of the acid; and after this I weighed it again, together with the cork, but I could not perceive the least difference in the weight. I conclude, however, from this experiment, that the acid air is heavier than the common air, because the mouth of the phial and the infide of it were evidently moiftened by the water which the acid vapour had attracted from the air, which moisture must have added to the weight of the phial.

SECTION V.

Of INFLAMMABLE AIR.

former expe

It will have appeared from my riments, that inflammable air confifts chiefly, if not wholly, of the union of an acid vapour with phlogiston; that as much of the phlogiston as contributes to make air inflammable is imbibed by the water in which it is agitated; that in this process it foon becomes fit for respiration, and by the continuance of it comes at length to extinguish flame. Thefe obfervations, and others which I have made upon this kind of air, have been confirmed by my later experiments, especially thofe in which I have connected electrical experiments with those on air.

The electric fpark taken in any kind of oil produces inflammable air, as I was led to obferve in the following manner. Having found, as will be mentioned hereafter, that ether doubles the quantity of any kind of air to which it is admitted; and being at that time engaged in a courfe of experiments to ascertain the effect of the electric matter on all the different kinds of air, I had the curiofity to try what it would do with common air, thus in

creafed

creased by means of ether. The very firft fpark, I obferved, increased the quantity of this air very confiderably, fo that I had very foon fix or eight times as much as I began with; and whereas water imbibes all the ether that is put to any kind of air, and leaves it without any visible change, with refpect to quantity or quality, this air, on the contrary, was not imbibed by water. It was also very little diminifhed by the mixture of nitrous air. From whence it was evident, that it had received an addition of some other kind of air, of which it now principally confifted.

In order to determine whether this effect was produced by the wire, or the cement by which the air was confined (as I thought it poffible that phlogiston might be discharged from them) I made the experiment in a glafs fyphon, fig. 19, and by that means I contrived to make the electric spark pass from quicksilver through the air on which I made the experiment, and the effect was the fame as before. At one time there happened to be a bubble of common air, without any ether, in one part of the fyphon, and another bubble with ether in another part of it; and it was very amufing to observe how the fame electric fparks diminished the former of these bubbles, and increased the latter.

It being evident that the ether occafioned the difference that was obfervable in these two cafes, I next proceeded to take the electric spark in a quantity of ether only, without any air whatever; and obferved that every spark produced a fmall bubble; and though, while the fparks were taken in the ether itself, the generation of air was flow, yet when fo much air was collected, that the fparks were obliged to pass through it, in order to come to the ether and the quickfilver on which it refted, the increafe was exceedingly rapid; fo that, making the experiment in small tubes, as fig. 16, the quickfilver foon receded beyond the striking distance. This air, by paffing through water, was diminished to about one third, and was inflammable.

One quantity of air produced in this manner from ether I fuffered to ftand two days in water, and after that I transferred it feveral times through the water, from one veffel to another, and ftill found that it was very strongly inflammable; so that I have no doubt of its being genuine inflammable air, like that which is produced from metals by acids, or by any other chemical process.

Air produced from ether, mixed both with common and nitrous air, was likewise inflammable;

mable; but in the cafe of the nitrous air, the original quantity bore a very fmall proportion to the quantity generated.

Concluding that the inflammable matter in this air came from the ether, as being of the clafs of oils, I tried other kinds of oil, as oil of olives, oil of turpentine, and effential oil of mint, taking the electric fpark in them, without any air to begin with, and found that inflammable air was produced in this manner from them all. The generation of air from oil of turpentine was the quickest, and from the oil of olives the flowest in these three cafes.

By the fame procefs I got inflammable air from Spirit of wine, and about as copioufly as from the effential oil of mint. This air continued in water a whole night, and when it was transferred into another veffel was strongly inflammable.

In all thefe cafes the inflammable matter might be supposed to arise from the inflammable fubftances on which the experiments were made. But finding that, by the fame procefs, I could get inflammable air from the volatile Spirit of fal ammoniac, I conclude that the phlogifton was in part fupplied by the electric matter itself. For though, as I have observed be