Opalescence phenomena in liquid mixtures

Abstract

It is well known that liquids which mix completely above a certain critical temperature, e.g. phenol and water, exhibit a strong and characteristic opalescence as the temperature of the mixture is lowered to a point slightly above that at which the components separate. A quantitative theory of this phenomenon was put forward by Einstein (Annalen der Physik, vol. 33, 1910) on the basis of thermodynamical reasoning, the spontaneous local fluctuations of concentration of the mixture being taken into account and the light-scattering due to the resulting fluctuations of refractive index being evaluated. He obtained as the expression for the light-scattering.