RELATIVE MOLAR VOLUME AND LIMITING SOLUBILITY OF HE-3 IN SUPERFLUID HE-4

The relative fractional molar volume α of He3 in a He3-He4 solution has been determined by a capacitance-measurement technique with a solution which remained in a single phase down to the lowest temperature of measurement, 31.7 mK. The observed temperature dependence at saturated vapor pressure is in excellent agreement with theory. Accounting for He3 kinetic and interaction effects, we deduce that α0, the fractional molar volume of He3 at zero (concentration, temperature, and pressure) is 0.286 ± 0.001. Measurements on more concentrated solutions permitted redetermination of the limiting solubility at zero temperature, with the result x0=0.0660±0.0006. © 1969 The American Physical Society.