  We present x-ray reflectivity measurements from the free surface of a liquid
gallium-bismuth alloy (Ga-Bi) in the temperature range close to the bulk
monotectic temperature $T_{mono} = 222$C. Our measurements indicate a
continuous formation of a thick wetting film at the free surface of the binary
system driven by the first order transition in the bulk at the monotectic
point. We show that the behavior observed is that of a complete wetting at a
tetra point of solid-liquid-liquid-vapor coexistance.

Statistical Mechanics;Materials Science