Thermodynamic Properties of Liquid Helium Three. Vapor Pressures below 1°K

Abstract

Vapor pressures of liquid ${\mathrm{He}}^3$ have been measured between 0.45° and 1.0°K. Temperatures were measured by the paramagnetic susceptibility of either ferric ammonium or chrome methylamine alum. The salts were calibrated above 1°K against ${\mathrm{He}}^3$ vapor pressures using the data of Abraham, Osborne, and Weinstock and the ${\mathrm{He}}^4$ temperature scales of Clement ($55E$) and of van Dijk and Durieux ($L55\mathrm{}$). The data obtained with the two salts were in good agreement with each other and indicate no preference between the two ${\mathrm{He}}^4$ scales.