Sessile drop experiments were performed on molten indium antimonide on clean quartz (fused silica) surfaces. A cell was constructed through which argon, helium, oxygen, hydrogen or a mixture of these was flowed at 600 degrees C. Some of the InSb was doped with 0.1% Ga. The surface tension a of oxide-free molten InSb was smaller in Ar than in He, may have increased with increasing O-2 in the gas, and was not influenced by Ga or H-2. The contact angle theta on silica was higher in the presence of Ar, was lowered by O-2, and was not influenced by H-2 or Ga. The work of adhesion Wand the surface energy sigma(sv) of the silica were higher in He than in Ar. The surface remained free of solid oxide only in flowing gas containing <= 0.8 ppm O-2. This behavior is attributed to reaction Of O-2 at the surface of the melt to form In2O gas. When solid oxide formed on Ga-doped material, it was strongly enriched in Ga, with the Ga/In ratio increasing with the concentration Of O-2 in the gas. Examination of published sessile-drop results for liquid metals and semiconductors on silica revealed that W and sigma(sv) were highest for reactive melts, in which SiO2 dissolves. For non-reactive melts, W and sigma(sv) were lower and theta higher in a gas than in a vacuum, regardless of whether the experiments had been carried out in sealed ampoules, a flowing gas, or dynamic vacuum. The implication is that the surface of silica was different in a vacuum than in a gas at similar to 1 bar. (c) 2006 Elsevier B.V. All rights reserved.