Inflammable air is not changed by being made to pass many times through a red-hot iron tube. It is also no more diminished or changed by the fumes of liver of sulphur, or by the electric spark, than I have before observed it to have been by a mixture of iron filings and brimstone. When the electric spark was taken in it, it was confined by a quantity of water tinged blue with the juice of archil, but the colour remained unchanged.
I put two wasps into inflammable air, and let them remain there a considerable time, one of them near an hour. They presently ceased to move, and seemed to be quite dead for about half an hour after they were taken into the open air; but then they came to life again, and presently after seemed to be as well as ever they had been.
SECTION VI.
Of Fixed Air.
The additions I have made to my observations on fixed air are neither numerous nor considerable.
The most important of them is a confirmation of my conjecture, that fixed air is capable of forming an union with phlogiston, and thereby becoming a kind of air that is not miscible with water. I had produced this effect before by means of iron filings and brimstone, fermenting in this kind of air; but I have since had a much more decisive and elegant proof of it by electricity. For after taking a small electric explosion, for about an hour, in the space of an inch of fixed air, confined in a glass tube one tenth of an inch in diameter, fig. 16, I found that when water was admitted to it, only one fourth of the air was imbibed. Probably the whole of it would have been rendered immiscible in water, if the electrical operation had been continued a sufficient time. This air continued several days in water, and was even agitated in water without any farther diminution. It was not, however, common air, for it was not diminished by nitrous air.
By means of iron filings and brimstone I have, since my former experiments, procured a considerable quantity of this kind of air in a method something different from that which I used before. For having placed a pot of this mixture under a receiver, and exhausted it with a pump of Mr. Smeaton's construction, I filled it with fixed air, and then left it plunged under water; so that no common air could have access to it. In this manner, and in about a week, there was, as near as I can recollect, one sixth, or at least one eighth of the whole converted into a permanent air, not imbibed by water.
From this experiment I expected that the same effect would have been produced on fixed air by the fumes of liver of sulphur; but I was disappointed in that expectation, which surprised me not a little; though this corresponds in some measure, to the effect of phlogiston exhaled from this substance on acid air. Perhaps more time may be requisite for this purpose, for this process was not continued more than a day and a night.