Low-temperature calorimetric data have been determined for n-pentane, nheptadecane, and n-octadecane. The quantities measured by adiabatic calorimetry include the heat capacities of the solid and liquid from approximately 12°to 300°o r 380°K ., heats and temperatures of transition and fusion, and purity of the samples. From these data and previously published data from this laboratory, the following chemical thermodynamic properties were calculated at selected temperatures from 0°to 300°K. for the n-paraffins from Cs to Cie in the condensed phase: Gibbs energy function, enthalpy function, enthalpy, entropy, and heat capacity. Polynomials in N, the number of carbon atoms, were fitted to the entropies of the 14 n-alkanes in the liquid state at 298.15°K ., and a quadratic fit significantly better than the linear relationship previously used.

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Low temperature calorimetry and vapor flow calorimetry were repeated for toluene with current accurate niethode to provide the following information: values of heat capacity for the solld ( l l°K . t o the triple point), the liquid (triple point to 371'K ), and the vapor (371 to 500°K.); the triple p i n t temperature; the heat of fusion; thermodynamic functions for the solid and liquid (0 t o 360'K.); heat of vaporlaation (341 to 410°K.); and parameters of the equation of state. The results were used to confirm a vibrational assignment and t o show that the internal rotation is essentially free, 8s expected from the sixfold symmetry. Thermodynamic functions for toluene in the ideal gas state ( 0 to 1600°K.) were calculated by methods of statistical mechanics.

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As part of a program to provide basic thermodynamic information for important petroleum constituents, low temperature calorimetric investigations were made of the following six bicyclic hydrocarbons: naphthalene, I-methylnaphthalene, 2-methylnaphthalene, 1,2,3,4-tetrahydronaphthalene, trans-decahydronaphthalene and cis-decahydronaphthalene. For each compound, measurements were made of the heat capacity in the solid and liquid states between 12 and 370"K., the heat of fusion, the triple-point temperature, the cryoscopic constants, and the purity of the sample. Isothermal transitions that occur in 1-methylnaphthalene, 2-methylnaphthalene and cis-decahydronaphthalene were studied, and values of the heats and temperatures of transition were determined. Unusual effects of impurity on the thermal pro erties of l-methylnaphthalene and cis-decahydronaphthalene in the remelting" and melting regions were observed. #he absence of a reorted thermal anomaly in liquid cis-decahydrona'khalene was demonstrated. From the low temperature thermal data for each compound, values of the following thermognamic functions in the solid and liquid states were computed at selected temperatures from 10 to 370°K.: (Faatd -H0o)/T, (Hsatd -H"o)/T, Hsatd -H'o, Saaa and C6atd.