Sound Velocity and Adiabatic Compressibility of Liquid Helium Three

Abstract

The velocity of first sound at 5 Mc/sec was measured in liquid ${\mathrm{He}}^{3}$ between 0.34 and 3.14\ifmmode^\circ\else\textdegree\fi{}K. The results are fitted within 0.2% by the equation $u=183.9\ensuremath{-}5.98{T}^{2}\ensuremath{-}0.130{T}^{3}\ensuremath{-}0.00176{T}^{8}$ (m/sec). Initial pressure coefficients of the sound velocities and a number of derived thermodynamic quantities are also reported.