Isomorphic description of the two-phase region of near-critical binary mixtures

The paper presents a general approach based on the hypothesis of field mixing designed to describe properties of binary mixtures around critical points, including the region of two-phase states. The efficacy of the technique is illustrated by derivation of an analytic equation for boundary curves of a binary mixture. The shapes of these curves are largely determined by the critical lines T-c(x) and P-c(x). Given the shapes of these curves, one can easily estimate the maximum pressure at which two-phase equilibrium is possible, and the width of the retrograde condensation region. (C) 1997 American Institute of Physics.