POLYMORPHISM AT HIGH PRESSURES. 



109 



There is the usual variation of the velocity of transition with tem- 

 perature. At temperatures above 130° the transition is so rapid that 

 no measurements of the rate were possible, whereas at 0° it was a 

 matter of an hour or two for the pressure to approach within values 



TABLE VI. 

 Carbamide. 



differing by 700 kgm. from above and below. It was possible at 0°, 

 however, by artificially changing the pressure and watching the sub- 

 sequent reaction, to shut the pressure within limits only 60 kgm. apart. 



