A method for separating homogeneous mixtures based upon equilibration of liquid and vapour phases. Substances that differ in volatility appear in different proportions in vapour and liquid phases at equilibrium with one another. Thus, vaporising part of a volatile liquid produces vapour and liquid products that differ in composition. This outcome constitutes a separation among the components in the original liquid. Through appropriate configurations of repeated vapor-liquid contactings, the degree of separation among components differing in volatility can be increased manyfold.