The estimation of the entropy and enthalpy associated with the magnetic ordering process was done by utilizing a Debye function to assist in drawing a smooth curve for the lattice heat capacity contribution. This yields 154 cal./g.f.m. for the enthalpy of transition and 1.05 cal./(g.f.m. °K.) for the corresponding entropy increment. These results can be compared with the entropy increment, 1.17 cal./(g.f.m. °K.), observed in the similar magnetic transition of US10 at 180°K.Acknowledgment. The authors appreciate the partial financial support of the U. S. Atomic Energy Commission and of the Selenium-Tellurium Development Association, Inc., and the cooperation of Wen-Kuei Wong and Mrs. Carolyn M. Barber in making the measurements and calculations. We thank Dr. H. L.Goering of the Chemistry and Chemical Engineering Department of Battelle Memorial Institute for his generosity in providing the calorimetric sample.

The enthalpy increments above 298°K. for solid and liquid thallous fluoride, bromide, and iodide were measured with a drop calorimeter. These data together with literature values for the absolute entropies were used to calculate the enthalpy, entropy, and free energy for these compounds. The thermodynamic functions for the gaseous phases of these compounds were calculated from molecular constant data.

The heat contents of zinc chloride and bromide were measured from room temperature to about 700°C. The heat capacities (cal/mole deg) of the solids were: 14.5+5.5×10—3T and 12.6+10.4×10—3T°K; those of the liquid were 24.1 and 27.2 cal/mole; and the heats of fusion were 2.45 and 3.74 kcal/mole. These thermal data, when combined with the entropies of evaporation of F. J. Keneshea and D. Cubicciotti [J. Chem. Phys. (to be published)], resulted in absolute gaseous entropies that were 5 eu larger than the values calculated from molecular constant data. The discrepancy can be resolved if the molecules are bent or have lower bending frequencies than the literature values.

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