Dielectric Constant, Density, Expansion Coefficient, and Entropy of LiquidHe3Under Pressure Below 1°K

By measuring the resonant frequency of an $\mathrm{LC}$ circuit containing a capacitor filled with liquid ${\mathrm{He}}^3$, the dielectric constant of the liquid was measured from 0.14 to 1°K at several pressures from 0.2 to 29.5 atmospheres. From these measurements the density, expansion coefficient at constant pressure, and the change in entropy on compression from saturated vapor pressure to higher pressures were determined. ${\alpha }_p$ was found to be negative and, hence, ${\left(\frac{\partial S}{\partial P}\right)}_T$ positive for all pressures below a certain temperature which increased monotonically with pressure, confirming behavior found by Brewer and Daunt. A minimum in the melting curve of ${\mathrm{He}}^3$ was found at $T=0.32\mathrm{}\pm 0.01°$K and $p=29.1\mathrm{}\pm 0.1$ atm. The results are compared with those obtained by other methods.