The oxygen content of liquid silicon increases proportionally to the oxygen content of the ambient helium‐oxygen mixture for oxygen partial pressurespO2°<8 mm Hg. This observation is explained by the proportionality between the oxygen partial pressurepO2° in the ambient gas and the SiO partial pressure on the surface of liquid silicon. ForpO2°>8 mm Hg the silicon melt is covered by a film of silica and asaturation value of about 2×1018oxygen atoms per cm3is observed in the crystallized sample.