The heat capacity of malononitrile, CH2( CN)2, has been determined by adiabatic calorimetry from 5' to 320OK. A gradual transition occurs in the stable form at 260.3OK. with an entropy increment of 1.15 cal. per mole O K . The compound melts at 304.9OK. with an entropy of melting of 8.46 cal. per mole ' K. Lowtemperature heat capacities were also made on the metastable crystal obtained by quenching the stable form through the 260.3OK. anomaly. This phase has a gradual transformation which takes place over the 137' to 151OK. with an excess entropy of 0.055 cal. per mole O K. The heat capacity (Cp), entropy ( S O ) , and Gibbs energy function [ -(GO -/ -/ : ) / T I at 298.15'K. are 26.36, 31.30, and 15.34 cal. per mole ' K., respectively. The approximate accord of the experimental entropy of gaseous malononitrile at 298.15'K. (68.5 =! z 0.4 cal. per mole O K . ) with the value (69.02) calculated from spectroscopic data indicates the absence of disorder in the crystal at Oo K.

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Heats of fusion of p-nitrotoluene, p-toluidine, benzophenone, diphenylamine, 1:1 benzophenone—diphenylamine complex, and 1:2 urea—phenol complex have been determined with the help of a thermistor calorimeter.

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