The Free Expansion of Gases; Memoirs by Gay-Lussac, Joule, and Joule and Thomson (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 Excerpt: ...force-pump employed in our preliminary experiments. The hydrogen, after passing through a tube filled with fragments of caustic potash, was forced, at a pressure of 68.4 lbs. on the inch, through a piece of leather in contact with the bulb of a small thermometer, the latter being protected from the water of the bath by a piece of india-rubber tube. At a temperature of about 10 Cent, a slight cooling effect was observed, which was found by repeated trials to be 0.076. The pressure of the atmosphere being 14.7 lbs., it would appear that the cooling effect experienced by this gas is only one-thirteenth of that observed with atmospheric air. We state this result with some reserve, on account of the imperfection of such experiments on a small scale, but there can be no doubt that the effect of hydrogen is vastly inferior to that of atmospheric air., Influence of Temperature on the Cooling Effect. By passing steam through pipes plunged into the water of the bath we were able to maintain it at a high temperature without a considerable variation. The passage of hot air speedily raised the temperature of the stem of the thermometer, as well as of the glass tube in which it was enclosed; but nevertheless the precaution was taken of enclosing the whole in a tin vessel, by means of which water in constant circulation with the water of the bath was kept within one or two inches of the level of the mercury in the thermometer. The bath was completely covered with a wooden lid, and the water kept in constant and vigorous agitation by a proper stirrer. See Part IV. TABLE XII. Experiment in which, 1st, air; 2d, carbonic acid; 3d, air, dried by quicklime, was forced through a plug consisting of 740 grs. of silk. Meau barometric pressure, 80.015, equivalent to 14.68 lbs. on th...