1185 



where Gktman proposes the question whellier there exist more than 

 two inodifications of cadmium between 0° and 100°. 



Cohen and Heluerman deduced from the equations (.-1) and (C), 

 found by them (as well as by Gf,tman) for their n- and y-cells 

 lespectively, that the metastabh transition point Cdy ^ Cd^ lies at 

 94°. 8. Although we know that the transition point of Cda^Cd^s 

 lies between 0° and 100°, we are not allowed to conclude that 

 there exist more than two stable modifications within this range of 

 temperatures. We found that the y-modification is always metastable 

 within this range and Getman, who used this modification in his 

 y-cells, evidently agrees with this opinion. 



Consequently his words: "the results of the present investigation, 

 however, seem to render the existence of more than two allotropic 

 modifications of cadmium between 0° and 100° extremely doubtful", 

 lose their significance.. Three different forms of cadmium may possibly 

 exist between 0° and 100°, but one oi' these {Cd/) \s a,\wa,ys metastable 

 within this lange of temperatures. 



S U M M A R Y. 



1. It has been demonstrated that in the assumptions made by 

 Getman in his paper on the allotropy of cadmium some mistakes 

 have crept in. Consequently the conclusions which he has drawn 

 from his careful experimental work ought to be i-evised. 



2. If these mistakes are removed Getman's results become identical 

 with those of Cohkn and Helderman. In this way Getman's work 

 has been a very welcome control as well as a confirmation of the 

 results formerly got by ourselves. 



Utrecht, Dec. 1917. van WB.qyy- Laboratory. 



