Surface Tension near the Critical Point

Abstract

IT is well known that when measured values of surface tension are plotted against the temperature a nearly linear law is obtained, but that as a rule the curve is concave upwards and approaches the critical point almost tangentially (even if not quite so) the surface tension being then zero. It must be borne in mind, however, that this statement is made with respect to the ‘measured values’. These, near the critical point, are usually made by means of the capillary tube method and it is tacitly assumed that if the tube is narrow enough. to be considered a ‘narrow tube’ at ordinary temperatures it will still be so at high temperatures.