Wetting Transition in Lutidine-Water Mixtures

A predicted general property of liquid mixtures, the transition from complete to partial wetting at a temperature away from the critical consolute point, is verified experimentally. The system 2,6-lutidine + water undergoes such a transition at $T-T_c\simeq 15$ K, as indicated by the difference in capillary parameters measured by the capillary rise and meniscus curvature in thin Pyrex tubes above this temperature. The experiment provides an estimate of the differential binding energy between the two species of fluid molecules and the wall.