POLYMORPHIC TRANSFORMATIONS OF SOLIDS. 



69 



son at high pressures. The transition point by extrapolation (the 

 lowest point was 240 kgm.) from the present measurements is 140°, 

 against 146° by Gossner.* The melting point extrapolates to 171.2°, 

 against the values 161.2° by Pohl in 1851 (quoted in the French 

 Tables), 173.8° by Wagner and Zerner,^ and 174.2° by Wassiljew.^ 



TABLE I. 



PoTASSirM SuLFOCY.\XIDE. 



It should be noticed that the extrapolated value of the melting point 

 is probably too high, because no account is taken of the certain curva- 

 ture of the melting curve. It is to be remarked that a high transition 

 temperature is not presumably more correct than a low one, as it is 

 in the case of melting. Impurity in the form of mixed crystals must 

 be proved before such a presumption can be recognized, and even then, 



4 B. Gossner, ZS. Kryst. 38, 110-168 (1903). 



5 K. L. Wagner and E. Zerner, Monatsh. Chem. 31, 833-841 (1910). 



6 H. Wassiljew, Chem. Centralbl. 1910, II, 56. 



