A Sonic Interferometer for Liquids


FROM thermodynamical considerations alone it should be possible to calculate the number of degrees of freedom, and consequently the association of molecules in the liquid state, if one could only determine the numerical difference between the specific heats at constant pressure and at constant volume. It is practically impossible, however, to obtain direct measurements of liquids at constant volume because of the, elasticity of the walls of the containing vessel. But this difficulty can be obviated if the velocity of a compression wave in the liquid can be ascertained with sufficient precision, because the numerical difference between the specific, heats can, by the aid of Newton's equation, be expressed as a function of the temperature, the coefficient of expansion, and the velocity of a compressional wave.

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HUBBARD, J., LOOMIS, A. A Sonic Interferometer for Liquids. Nature 120, 189 (1927). https://doi.org/10.1038/120189a0

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