240 IOWA ACADEMY OF SCIENCE 



In summing up the results of the experiments it was con- 

 cluded that the occluded air effects the difference in bursting. 

 It does this first, by acting as nuclei for crystallization so that 

 ordinary water freezes less solidly than boiled water. Second, 

 by causing the ice to freeze less solidly, especially at the center, 

 until a very low temperature is reached the pressure along 

 the center is relieved by the water and slush flowing away. 

 Third, the air acts as a compressible medium, which relieves 

 the pressure by an unknown amount. 



Department of Physics, 

 State University. 



