A STUDY OF THE COEXISTENCE OF THE LIQUID AND GASEOUS STATES OF AGGREGATION IN THE CRITICAL TEMPERATURE REGION. ETHANE

Abstract

A careful study has been made of the position and nature of the meniscus and the distribution of opalescence in bombs containing ethane as the critical temperature is approached. Photographs of the phenomena have been made. The effect of shaking has been observed, and a type of shaking is described that is believed to hasten the attainment of equilibrium between the liquid and vapour phases. Using this type of stirring the coexistence curve of ethane has been determined. Relative temperature measurements are accurate to within ± 0.001 ° C.; absolute temperature measurements, to within ± 0.015 °C. Density measurements are believed accurate to within 1:3000. The limiting curve has the classical parabolic shape up to 32.23 °C., at which point the slope changes abruptly and the curve becomes flat along the density axis. The authors believe that at this temperature a dispersion of liquid and vapour occurs and that liquid still persists above this temperature. It is shown that the critical temperature as ordinarily determined in a stationary bomb cannot be accurately determined. The critical temperature can be determined precisely and without ambiguity when the bomb is shaken, and it is recommended that the value obtained in this way be used instead, as a physical measurement.