FICKIAN DIFFUSION IN BINARY-MIXTURES THAT FORM 2 LIQUID-PHASES

New data on the variation of the diffusion coefficient with concentrat ion in binary nonideal liquid mixtures are presented. The diffusion co efficients weve measured with laser holography with an improved analys is procedure and are primarily in systems that form two liquid phases. The results show that for such systems the diffusion coefficient is c onstant if a chemical-potential driving force is used IF, however the miscibility gap is wide, the Schreiner equation (Schreiner, 1922) is s hown to be more accurate than relations that consider the variation of viscosity. Cluster theories developed for diffusion behavior near cri tical points were found to to explain the data well only in water orga nic systems on the water-rich side.