Iron filings and brimstone, I have observed, ferment with great heat in nitrous air, and I have since observed that this process is attended with greater heat in fixed air than in common air.
Though fixed air incorporated with water dissolves iron, fixed air without water has no such power, as I observed before. I imagined that, if it could have dissolved iron, the phlogiston would have united with the air, and have made it immiscible with water, as in the former instances; but after being confined in a phial full of nails from the 15th of December to the 4th of October following, neither the iron nor the air appeared to have been affected by their mutual contact.
Having exposed equal quantities of common and fixed air, in equal and similar cylindrical glass vessels, to equal degrees of heat, by placing them before a fire, and frequently changing their situations, I observed that they were expanded exactly alike, and when removed from the fire they both recovered their former dimensions.
Having had some small suspicion that liver of sulphur, besides emitting phlogiston, might also yield some fixed air (which is known to be contained in the salt of tartar from which it is made) I mixed the two ingredients, viz. salt of tartar and brimstone, and putting them into a thin phial, and applying the flame of a candle to it, so as to form the liver of sulphur, I received the air that came from it in this process in a vessel of quicksilver. In this manner I procured a very considerable quantity of fixed air, so that I judged it was all discharged from the tartar. But though it is possible that a small quantity of it may remain in liver of sulphur, when it is made in the most perfect manner, it is not probable that it can be expelled without heat.
SECTION VII.
Miscellaneous Experiments.
1. It is something extraordinary that, though ether, as I found, cannot be made to assume the form of air (the vapour arising from it by heat, being soon condensed by cold, even in quicksilver) yet that a very small quantity of ether put to any kind of air, except the acid, and alkaline, which it imbibes, almost instantly doubles the apparent quantity of it; but upon passing this air through water, it is presently reduced to its original quantity again, with little or no change of quality.
I put about the quantity of half a nut-shell full of ether, inclosed in a glass tube, through a body of quicksilver, into an ounce measure of common air, confined by quicksilver; upon which it presently began to expand, till it occupied the space of two ounce measures. It then gradually contracted about one sixth of an ounce measure. Putting more ether to it, it again expanded to two ounce measures; but no more addition of ether would make it expand any farther. Withdrawing the quicksilver, and admitting water to this air, without any agitation, it began to be absorbed; but only about half an ounce measure had disappeared after it had stood an hour in the water. But by once passing it through water the air was reduced to its original dimensions. Being tried by a mixture of nitrous air, it appeared not to be so good as fresh air, though the injury it had received was not considerable.