POLYMORPHIC TRANSFORMATIONS OF SOLIDS. 



119 



possible for a four phase system actually exist; six equilibrium lines 

 and three triple points. The experimental values for pressure and 

 temperature are shown in Figure 31, the experimental values of AF 

 in Figure 32, the computed values of AF and AE in Figure 33, and the 



23456789 10 U12 

 Pressure, kgm./cm.^ x 10^ 



Urethan 



Figure 32. Urethan. The observed changes of volume. 



1 2 3 4 5 6 7 8 9 10 11 12 

 Pressure, kgm./cm.^ x 10^ 

 Urethan 



Figure 33. Urethan. The computed values of the heats of transition and 

 the changes of internal energy. 



numerical values are given in Table XIV. It was necessary to dis- 

 card two points in the immediate neighborhood of the L-I-II triple 

 point, which were determined before it was known that there was 

 a triple point here. The three melting curves are entirely normal. 



