Shape of the Coexistence Curve near a Plait Point in a Three-Component System

The degree, d, of the coexistence curve near the plait point in the system ethanol–water–chloroform has been determined from measurements of the volumes of coexisting phases in sealed samples. The result, d = 2.67 ± 0.12, shows the deviation from the mean-field d = 2 and shows also the renormalization d = (1 − α′) / β that is predicted by current theories. (1 / β is the degree of the temperature-density coexistence curve in a pure fluid and α′ is the index of its constant-volume specific heat singularity.)