Measurements of Ultrasonic Absorption and Velocity in Liquid Mixtures

The absorption (α) and velocity (V) of sound in liquid mixtures were measured at four frequencies (ν) in the range 3.8 to 19.2 mc, using the Debye-Sears-Lucas-Biquard optical technique improved by the addition of a differential photoelectric cell indicator. This improvement permitted the use of lower sound intensities together with a wider sound beam than in the visual extinction method, thus improving conditions with respect to cavitation and beam distortion. In the mixtures investigated, α/ν2 was found to be independent of frequency within the accuracy of the method, and there was no measurable dispersion of acoustic velocity. An absorption peak at intermediate concentrations not shifting with frequency was found in mixtures of acetone and water, and of ethyl alcohol and water, but was not in evidence in mixtures of acetone and ethyl alcohol, and of glycerol and water. The absorption peaks await theoretical explanation.