Statistical Mechanics of LiquidHe3

The partition function which Feynman has proposed for liquid ${\mathrm{He}}^4$ is extended to the case of liquid ${\mathrm{He}}^3$, taking into account the Fermi-Dirac statistics and the nuclear spin of ½. The nuclear magnetic susceptibility is calculated and compared with the observation of Fairbank, Ard, and Walters. Theoretical and experimental curves fit when the effective mass of the ${\mathrm{He}}^3$ atom is taken about four times its true mass. The entropy of the system has not been calculated.