EFFECT OF DILUTE SILICA-GEL ON PHASE-SEPARATION OF A BINARY MIXTURE

We report the results of an experimental study of the effect of a dilute silica network on critical phenomena in a binary mixture of 2.6-lutidine and water. Light-scattering measurements of this system show that its structure does not differ significantly from that of the gel, but that the scattered intensity increases dramatically as the two-phase region is approached. We interpret these results in terms of a layer of lutidine-rich fluid adsorbed on the silica surface and the resulting changes in concentration of the nonadsorbed fluid.