EXPERIMENTAL-STUDY OF THE CRITICAL LAWS FOR THE SURFACE TENSIONS ALONG THE CRITICAL ISOCHORE, AND THE COEXISTENCE CURVE AND FOR THE LIQUID-LIQUID INTERFACE - WATER-2,5 LUTIDINE SYSTEM

Using the Wilhelmy method for measuring surface tensions-sigma-k along the critical <<isochore>> and along the coexistence curve vs. the temperature for the water-2,5 lutidine system, we verified the limiting laws established by Widom and coworkers: sigma-k - sigma-c = = A(T - T(c)) + B(k)(T - T(c))-mu (subscript c for critical, k for either isochore, left branch or right branch of coexistence curve, mu is the critical exponent of the surface tension). The value of mu = 1.21 +/- 0.09 is very close to the theoretical value, i.e. 1.26. In addition, the interfacial tension sigma-beta-gamma between the two liquid coexistent phases obeys the law: sigma-beta-gamma = B(i)(T - T(c))-mu. The numerical values of the B(k)'s and B(i) show that the Antonoff rule is respected.