1182 



with the solution of an electrolvle in order to exclude retardation. 

 Neither mj' own experience in this field of research nor that of 

 others mentioned in the literature agrees with Gktman's statement, 

 which has been given above in italics. 



11. We shall consider now another part of Getman's paper. He 

 also repeated the experiments carried out by Cohen and Helderman 

 in order to prove in another way the reality of existence of ('d,3. 

 About this part of our investigations we have written'): In order 

 to ascertain if the e. m. f. ot the /?-cells has a real significance, 

 experiments may be carried out on the following lines : At temperatures 

 above the transition point of the transformation Cd-tt'^Cd-^ 

 (which we found to lie in the vicinity of 60° by dilatometric 

 measurements) the e. m. f. of fccells must be higher than that of 

 /i-cells. After cooling the cells below the transition point mentioned, 

 the contrary will be the case. 



Our experiments were carried out in the following way : We 

 constructed a large number of Hulett-ccHs ; one of these, the e. m. f. 

 of which had been originally 0.050 volt at 25°. 0, attained a constant 

 e. m. f. of 0.047 volt (at 25°.0) after 4 weeks at 47^5. 



We combined this cell (N". 7) with another (N'. 22), the e m. f. 

 of which was 0.048 Volt at 25°.0. The two cells AB (N". 7) and 

 CD (N". 22) were connected by a siphon which contained the 



same solution of cadmium sulphate 



as was present in the cells. (Fig. 3). 



The lateral tube E of the siphon 



was closed by a rubber tube F in 



which was put a glass rod G. The 



entire apparatus was brought into a 



thermostat which could be kept at 



will at 25°.0 or64°.5. We measured 



the e. m. f. between the cadmium 



which had been electrolytically 



deposited on the platinum spirals A 



* CD and C against the common amalgam 



Fig. 3. electrode B (12.5 7„ by weight). 



It is absolutely necessary to use a common electrode as the 



cadmium amalgam of 12.5 "/o by weight does not form a 



1) These Proceedings 17. 638 (1914); Zeitschr. f. physik. Chemie 89, 493 

 (1915); Transactions of the Faraday Society 10, 216 (1915). 



