ABSTRACTSome possible ceramic applications of the Toepler mercury pump as employed in determination of gases in various materials are discussed. The procedure followed in measuring the gases given off by a clay slip at reduced pressures is described. It was found that 4.65% of gases by volume are removed from a sample of clay slip by reducing the pressure on the sample to boiling (25 mm.). An additional 0.18% of gases was cvolved between the boiling pressure and 1.8 mm. at which pressure the sample was dry.