AbstractsChemistry

A new type of adiabatic electrical calorimeter has been designed for use at high pressures, by means of which the heat capacities of gases at constant volume can be determined over short temperature ranges with an accuracy of about 0.2%. The arrangements are such that the lags occurring after a change in temperature in the critical region can be followed, and their effect as an error in the heat capacity measurement eliminated. A very efficient low temperature fractionating unit has been constructed, in order to assure the purity of the material used. The heat capacity of ethylene has been determined for three fillings near the critical density, and for a fourth filling somewhat removed from this value. These are the first heat measurements made on ethylene in the critical range, and the first measurements made on any material, in which the time lags which occur near the critical temperature are taken into account, and their effect as an error in the heat capacity measurement eliminated. [...]