Design, Construction and Testing of a Heat of Vaporization Calorimeter useful in the Vapor Pressure Range 1 to 0.001(0. 0001)mm Hg at 25°C

摘要

A micro-calorimeter has been built with the purpose of determining heats of vaporization of substances in the vapor pressure range ca. 1 to 10-3 to 10-4 mm Hg. The calorimeter consists of a Knudsen-cell from which the cubstanct is evaporated directly into hich-vacuuir space. Special care has been taken to ascertain iso-thermal working conditions and to prevent contamination of the vacuuir system by vapors, harmful increase of pressure due to the pre sense of vapor outride the calorimeter and heat leak errors. The system has been parity checked, final testing and preliminary measurements are now under way.