Chemical Affinity in terms of Electromotive Force. 299 



3. Bright Copper Plates partially but not completely 

 Electro-coated. 



Observations with Diffusion-cells. Probable error not 

 exceeding +'75 millivolt. 





*=-940 



w=-461 



^=•094 



i*=l 972 



•940 

 •461 



41 



9-3 

 5-2 



19-7 



15-6 

 104 



4. Bright Copper Plates. 

 Observations with Diffusion-cells. Probable error not 



exceeding ±1*0 millivolt. 





ft =-461 



n =-094 



*»= 1*972 

 •461 



69 



16-8 

 9-9 



The following table represents these four seis of values re- 

 duced, by interpolation, to a common origin (m = 2*0) and 

 common abscissSB: the curves marked respectively 1, 2, 3, and 4, 

 fig. 2, represent these sets of reduced values : curve 5 simi- 

 larly represents the average values for amalgamated zinc and 

 zinc-sulphate solution similarly reduced ; evidently nearly 

 coinciding with curve 2 (electro -copper). 



Difference of Potential set up between Solutions of 2*0 OuS0 4 

 100 H 2 and nCuS0 4 100H 2 O. 





Amalgamated 

 copper. 



Electro- 

 copper. 



Bright copper 

 only partially 

 electro-coated. 



Bright 

 copper. 



»=20 



= 10 

 = -5 

 = 1 







59 

 11-7 



27-2 







5'8 

 10-9 

 220 







4-0 



90 



19-6 







3-5 



6-6 



16-8 



155. A number of observations were similarly made with 

 various cadmium-sulphate solutions ; employing different kinds 

 of cadmium plates : only diffusion-cells were used in this 

 series of experiments. The following results were obtained 

 as final average values, showing that amalgamated plates 

 (wet with liquid amalgam) give higher, and bright plates 

 lower values than electro-coated plates, just as with zinc and 

 copper, 



X2 



