1183 



heterogeneous system at 64°. 5; its e.m.f. is then a function of its 

 composition. The use of tnio amalgam electrodes B and D might 

 give rise to serious mistakes, if there were only small differences 

 in their composition. The absolute e.m.f. of our amalgam electrode 

 against cadmium in A and C does not play any role in our meas- 

 urements. 



In this way we found : 



E.m.f. at 25°.0 E.m.f. at 64°.b E.m.f. at 25°.0 



Cell 7 0.04741 0.04029 0.04741 



Cell 22 0.04815 0.03979 0.04806 



A second experiment with two cells (N". 4 and 8) newly con- 

 structed, gave the following results: 



E.m.f. at 25°.0 E.m.f. at 64°.5 E.m.f. at 25°.0 



Cell 8 0.04757 0.04737 0.04776 



Cell 4 0.04839 0.04633 0.04789 



Getman, on repeating these experiments ^) got the same results, 

 viz. there takes place a reversal of poles, if the cells are measured 

 at the temperatures indicated above. This is shown by the following 

 measurements of Getman. 



E.m.f. at 25°.0 E.m.f. at 64°. 5 E.m.f. at 25°.0 

 Cell B 1 0.04729 0.04734 0.04772 



Cell A—1 0.04823 0.04652 0.04822 



With reference to these results Getman says: "It will be observed 

 that at 64°. 5, the e. m. f. of cells 7, 8 and B-\ was greater than 

 that of cells 22, 4 and A-\, whereas at 25°, the e. m. f. of the 

 latter group of cells was greater than that of the former. From 

 this inversion of poles Cohen concluded that an actual transformation 

 of Cda into Cd^ occurs in the neighbourhood of 60°". 



Again a mistake has crept into Gktman's statement. Evidently we 

 are not allowed to conclude from this inversion of |)oles that a 

 transition point exists in the vicinity of 60°, as the e.m.f. of the cells 

 has not been measured at a sufficient number of different temperatures 

 between 25° and 64°. 5. We only concluded from our experiments 

 that the value of the ei m. f. of our /?-cells (48 millivolt at 25°. 0) 

 has a real significance and has to be ascribed to the existence of 

 Cd-jiin connection with our pycnometric and dilatometric measurements. 



12. With regard to the sentence "from this inversion of poles 



>) The fact that Getman used cells which contained an 8% amalgam, whereas 

 the amalgam of our cells contained IS.ö'^/q of cadmium does not maUer herey as 

 both theses amalgams are heterogeneous at 25*^.0 and homogeneous liquid at 64 ; 5. 



