Ultrasonic Interferometry for Liquid Media

A resumé of the theory of the ultrasonic interferometer is given and adapted for use with liquid media where the term $\rho v$ is very large (approximately ${10}^5$) in comparison with that occurring in gases (approximately 40). The differences of the observed phenomena due to this factor are discussed together with a method of obtaining the coefficient of absorption of ultrasonic waves in liquids, and the "effective" coefficient of reflection of the waves at a liquid-metal boundary. Measurements at 2.79 and 8.37 megacycles yield for the "frequency-free" coefficient of absorption in water approximately 19×${10}^{-17\mathrm{}}$ while the coefficient of reflection varies from 0.7 to 0.9 at boundary surfaces of monel metal and brass.