Page:Experimental researches in chemistry and.djvu/117

102 The fluid carbonic acid was supplied to me by Mr. Addams, in his perfect apparatus, in portions of about 220 cubic inches each. The solid carbonic acid, when produced from it, was preserved in a glass; itself retained in the middle of three concentric glass jars, separated from each other by dry jackets of woollen cloth. So effectual was this arrangement, that I have frequently worked for a whole day of twelve and fourteen hours, having solid carbonic acid in the reservoir, and enough for all the baths I required during the whole time, produced by one supply of 220 cubic inches.

By the apparatus, and in the manner now described, all the gases before condensed were very easily reduced, and some new results were obtained. When a gas was liquefied, it was easy to close the stopcock, and then remove the condensing tube with the fluid from the rest of the apparatus. But in order to preserve the liquid from escaping as gas, a further precaution was necessary; namely, to cover over the exposed end of the stopcock by a blank female screw-cap and leaden washer, and also to tighten perfectly the screw of the stopcock plug. With these precautions I have kept carbonic acid, nitrous oxide, fluosilicon, &c. for several days.

Even with gases which could be condensed by the carbonic acid bath in air, this apparatus in the air-pump had, in one respect, the advantage; for when the condensing tube was lifted out of the bath into the air, it immediately became covered with hoar-frost, obscuring the view of that which was within; but in vacuo this was not the case, and the contents of the tube could be very well examined by the eye.

Olefiant Gas.—This gas condensed into a clear, colourless, transparent fluid, but did not become solid even in the carbonic acid bath in vacuo; whether this was because the temperature was not low enough, or for other reasons referred to in the account of euchlorine, is uncertain.