Chemical Affinity in terms of Electromotive Force. 297 



Difference of Potential set up between Solutions of 5*0 ZnS0 4 

 100 H 2 and nZnS0 4 100 H 2 0. 





Amalgamated zinc 

 (average above cited). 



Electro- 

 zinc. 



Bright 

 zinc. 



n = b'0 

 = 30 

 = 1-0 

 =01 





 11-8 

 232 



395 







8-6 

 17-5 

 27-9 







7-7 

 15-8 

 25-3 



Evidently the values with amalgamated zinc are the 

 highest, and those with bright zinc the lowest. 



154. II. Variations of Potential due to Variation in Strength 

 of Copper -sulphate Solution. 



1. Electro-copper Plates. 



A. Observations with the Electrometer. Probable error 

 not exceeding + 1 millivolt. 



Values of m. 



Values of n. 



1-10 



•55 



•167 



21 

 11 



•55 



5 



11 

 6 



205 



13-5 



9-5 



B. With two Opposed Cells. Probable error usually well 

 within +'5 millivolt, and often less than ±*25 millivolt. 





^=•940 



w=-461 



rc=-094 



m= 1-972 



= -940 

 = -461 



5-6 



10-3 

 4-7 



224 

 16-8 

 121 



C. With Diffusion-cells. Probable error less than +*5 



millivolt. 





n=M 



»=47 



^=•227 



m = V88 

 = -99 

 = -47 



5-7 



10-5 



4-8 



16-3 



10-6 



47 



On graphical representation after reduction, by interpola- 

 tion, to common origin (when m = 2*0) and common abscissaB, 

 these three sets of figures are found to coincide within reason- 

 able error-limits, thus confirming the results arrived at above 

 with amalgamated zinc plates and zinc-sulphate solutions. 

 Further, it is noticeable that these values are all close to those 

 similarly obtained with zinc-sulphate solutions and amalga- 

 mated zinc plates when similarly reduced. 



Phil. Mag. S. 5. Vol. 17. No. 106. April 1884. X 



