The vapour pressures as a function of temperature of the methyl esters of alkanoic acids from butanoic to eicosanoic acid, have been measured using two different techniques: the static diaphragm and spinning rotor manometry and the combined torsion mass-loss effusion. Combined with data available from literature, the new data have been processed using the thermodynamic regression equation proposed by Clarke and Glew. The results of this research are reliable vapour pressures and the thermodynamic properties of vaporisation.

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The heat capacities of 1,4-dichlorobenzene, 1,4-dibromobenzene, and 1,3,5-trichlorobenzene from 5 K to 380 K and 1,3,5-tribromobenzene from 5 K to 410 K were measured by adiabatic calorimetry. The experimental data were used to calculate the molar entropy and enthalpy values relative to 0 K. Apart from 1,4-dichlorobenzene, the substances do not show any solid-solid transitions. Molar enthalpies of fusion and melting-point temperatures were determined. The results, given in order, are (17 907

Sub-ambient calibration of DSCs is a problem because there are few reference substances, and every available substance has its drawbacks. One of the possibilities is the low-temperature solid-solid transition of adamantane. High-accuracy adiabatic calorimetry results are, however, only available from one source. Therefore it was decided to measure the transition with our adiabatic calorimeter. Although our results show some deviation from the results reported in the literature source -our transition temperature (208.0 K) is 0.6 K lower and our enthalpy of transition (3213 J mol −1 ) is 5% smaller -we strongly believe this transition can be useful for the calibration of DSCs. Because the heat capacity of the low-temperature phase significantly increases well below the transition temperature, we propose to use a linear base line drawn as a tangent to the (almost) linear heat capacity curve above the transition region and start the integration at the temperature at which the drawn base line crosses the measured curve (at about 190 K). With this integration we found a heat of transition of 3094 J mol −1 (=22.7 J g −1 ).