Vapor Pressures ofHe3—He4Mixtures

Vapor pressures, $P_x$, of ${\mathrm{He}}^3$—${\mathrm{He}}^4$ mixtures ranging in liquid mole fraction, $X$, from 0.1 to 0.9 have been measured between 0.6° and 2.4°K versus the vapor pressure, ${P_3}^0$, of liquid ${\mathrm{He}}^3$. Except for sharp breaks in the vicinity of the lambda and stratification temperatures of some of the mixtures, $\frac{P_x}{{P_3}^0}$ is found to vary slowly and smoothly with $X$ and with temperature. Contrary to much of the work of other authors, there are no breaks at the ${\mathrm{He}}^4$ lambda temperature.