Excess Ultrasonic Attenuation and Intrinsic‐Volume Viscosity in Liquid Argon

The ultrasonic attenuation has been measured in liquid argon by pulse techniques with a single quartz transducer, variable‐path‐length apparatus. Measurements have been made at temperatures between 84° and 112°K with pressures up to 10 atm. The measured attenuation depends linearly on the square of the frequency over the range 30–70 Mc/sec; however, the measured values exceed the values calculated from the classical Stokes—Kirchhoff expression.The excess attenuation has been interpreted as evidence for the existence of the volume viscosity in liquid argon. The volume viscosity coefficient has been calculated and the results compared with those of the current theories of liquid‐transport phenomena.