THE VELOCITY OF SOUND IN HELIUM AT TEMPERATURES −78 °C. TO 200 °C. AND PRESSURES UP TO 70 ATMOSPHERES

Abstract

The velocity of sound in pure helium gas has been measured as a function of pressure at −78°, 0°, 50°, 100°, and 200 °C., using an ultrasonic interferometer of the double crystal type. From the sound velocity data second viral coefficients were obtained, and the ratio of specific heats was derived as a function of pressure.