334 EARLE C. GREGG, JR. 



of cavitation. Dognon and Biancani {18} have investigated this 

 rather thoroughly and have arrived at a general rule for this effect in 

 fatty bodies and liquid or coagulated proteins. Tables III, IV, and 

 V from Pohlmann (30) and Dognon and Biancani (18) show the re- 

 sults of such investigations. Table III shows that the temperature 

 rise is less in a gelatin solution than in water even though gelatin is 

 expected to have a higher absorption. This is probably due to the 



TABLE III 



Rise in Temperature in 2 Ml. of Various Liquids for a Ten Second Ultrasonic 



Exposure 



Liquid • AT, °C. 



Water 2 



Alcohol 3.5 



Glycerol 10 



Liquid paraffin , 10 



Gelatin solution 1 



Gelatin gel 1 



Stearic acid 36 



Wax 44 



TABLE IV 

 Temperature Rise in Various Materials after a Thirty Second Ultrasonic Exposure 



Material AT, °C. 



Agar gel 



Brain 9.5 



Coagulated egg albumin 2 



Egg albumin 2 



Egg yolk 11 



Fat 25 



Liver 9 



TABLE V 



Absorption Coefficients and Half- Value Thicknesses for Various Tissues 



Material 



Layer of fat . . . . 

 Layer of muscle. 

 Fat plus muscle . 

 Fat plus muscle . 



