504 



two nearest ones with smaller distances than those of the rest of 

 the surrounding atoms, two valencies especially come to the foreground. 



In this connection it might be interesting, to investigate, whether 

 the deviating conduct, observed by Gküneisen ') in the course of 

 the conductivity at low temperatures for cadmium, tin, and mercury, 

 and which he ascribed to the metals not being regular, is not found 

 with the grey tin, or whether the diamond-structure still causes a 

 deviation in the conductivity at low temperatures from the conduct 

 of the metals crystallising in cubes with centered faces. 



We heartily thank Prof. Keksom for the great interest, which he 

 always showed us. 



^) E. Ghüneisen. Verh. D. physik. Ges. 20 (1918), p. 36. 



