COEXISTENCE PHENOMENA IN THE CRITICAL REGION: II. INFLUENCE OF GRAVITY ON THE COEXISTENCE CURVES OF ETHANE, ETHYLENE, AND XENON

Abstract

Liquid–vapor coexistence curves of ethane, ethylene, and xenon have been measured in the region of the critical point. Impurities present in the ethane and ethylene gave retrograde systems; reduction of the impurities yielded coexistence curves which were flat along the temperature axis to 0.001 °C. When the height of the ethylene system was decreased the range of densities over which the curve was flat was diminished. Stirring of the system caused the curve to be rounded. Similar results, confirming those of Weinberger and Schneider, were obtained with xenon. The observed behavior is in good agreement with the hypothesis that the major part of the flat top effect is due to gravitational compression.