A theory of nonathermal solns. for nonelectrolytes was established by a thermodn. method. This theory does not contain any adjustable parameters. The excess Gibbs free energy of liquid mixtures can be predicted by properties of pure components which are related to their internal pressure. The excess enthalpy and entropy can also be calculated, if the vol. of liquid mixture is known. The results of prediction show that the agreement with experimental values prevails over that by the Scatchard-Hildebrand theory of regular solns. and its modified version, SHFH theory for most of thirty-seven binary systems.

Key words: NON ELECTROLYTE, GIBBS FREE ENERGY, INTRINSIC PRESSURE