The heat capacity of benzene vapor was measured at two or more pressures at each of five temperatures in the range 68° to 198°C; and values of Cpo, the heat capacity in the ideal gas state, were obtained. By assuming a moderate degree of anharmonicity of the vibrations, it was possible to obtain excellent agreement between values of Cpo calculated statistically from spectroscopic data, and the observed values. An empirical equation for the second virial coefficient of benzene vapor was obtained from the observed values of (∂Cp/∂P)T, and heat of vaporization and vapor pressure data.

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Determined by Mr. H. J. Coleman of this station.
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