690 BEI.L SYSTEM TECHNICAL JOURNAL 



meters/sec). Solutions in water of various other liquids (and of some solids) 

 give parabolic velocity vs. temperature curves like that for water but with the 

 peak velocity and peak temperature values shifting with the concentration 

 of the solution. In general increasing the concentration raises the peak 

 velocity sHghtly and lowers the peak temperature markedly from the values 

 for water alone. It has also been found possible by compounding three- 

 component solutions to adjust the values of the peak velocity and peak 

 temperature independently within a narrow range of velocities and a wide 

 range of temperatures. 



Measurements of Ultrasonic Absorption and Velocity in Liquid Mixtures}^ 

 F. H. Willis. The absorption {a) and velocity (V) of sound in liquid 

 mixtures were measured at four frequencies {v) 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 improvmg conditions with 

 respect to cavitation and beam distortion. In the mi.xtures investigated, 

 a/v^ 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. 



Measuring Inter-Electrode Capacitances?^ C. H. Young. New bridge, 

 developed for measurement of extremely small values in high frequency 

 tubes, useful to two-billionths of a microfarad. 



^^Jour. Acous. Soc. Amer., January 1947. 

 25 Tele-Tech, February 1947. 



