An empirical equation-of-state for solid-fluid interfacial free energies

The contact angle,, formed by a liquid on a solid surface in air depends on the solid-air (_S), liquid-air (_L) and solid-liquid (_SL) interfacial free energies, as described by Young's equation. Critical examination of reported contact angles for numerous liquids and solids leads to an empirical correlation between_sL and both_Y and_S. Combination of this correlation with Young's equation gives an empirical relation allowing calculation of_S from_L and Calculations made with these empirical relations agree well with estimations of_S obtained by the method of critical spreading, and are consistent with Young's equation.Founded and supported by F. Hoffmann-La Roche and Co., Limited Company, Basel, Switzerland.