Abstract
CAN there be a crowding of the particles of a gas to a much smaller compass without its being markedly heated? Can a gas expand without being cooled? It is probable that nearly every physicist will give negative answers to these questions, and yet the fact that such conditions may occur sometimes seems well established. The present writer, in 1889, attempted to determine the actual heating of air when compressed by a pump connected with the cylinder by a long tube, and found that the temperature was raised about 4° F. for a compression of 10 inches above atmospheric pressure. In like manner, on expanding this compressed air into the free atmosphere, it was found that the cooling was about 4°. These results were published in Science, vol. xv. p. 387, and were strongly combated by Prof. Ferrel and Prof. Marvin. Prof. Ferrel advanced, as applicable in this case, the well-known thermodynamic formula for the computation of the heat developed in a gas when compressed, as follows:— t/ t′=(p/p′)˙291 in which t and t′ are the absolute temperatures corresponding to the pressures p and p'. Sir Wm. Thomson has given this formula in slightly different form, and with a larger exponent (see “Encyclopædia Britannica,” vol. vii. p. 814). Prof. Ferrel found that, under the experimental conditions above, the heating should have been 43°, and the cooling 45°? (38°) (see American Meteorological Journal, vol. xii. pp. 339 and 340).
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HAZEN, H. A Question in Physics. Nature 46, 55 (1892). https://doi.org/10.1038/046055a0
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DOI: https://doi.org/10.1038/046055a0
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