Mean-field critical behaviour of susceptibility near a curve of plait points in a ternary liquid mixture

We report on light scattering investigations in the vicinity of plait points in a ternary liquid mixture of ethanol + water + sodium carbonate. The plait points that were explored occur in the temperature range of 300 to 378 K. The coordinates of these points were extracted from the coexistence surface of the ternary liquid system. The approach to each of these plait points is quantified better by mean-field (or classical) critical behaviour (exponent gamma = 1) than by 3-D Ising behaviour (gamma = 1.24). The role of electrolytes in modifying the anticipated 3-D Ising behaviour in this system is highlighted. (C) 1998 Published by Elsevier Science B.V.