192 



Dr. C. R. A. Wright and Mr. C. Thompson. [May 3, 



for some hours longer; the following figures refer to this latter 

 period when nearly constant but lower values were obtained. 

 Cadmium did not alter so markedly on standing ; silver gave very 

 irregular values. 



E.M.F. of Cells set up with Amalgamated Zinc, Brightened Cadmium, 

 and Pure Silver Foil in mH 3 SO 4 ,100H 2 O. 





Zinc. 



Cadmium. 



Silver. 



m = 2*5. 



m = 10. 



m = 2-5. 



m = 10. 



m = 10. 



Platinum sponge coat ed 













with platinum black. 





1-750 





1-505 



About 0-58 





1-681 



1-628 



1-356 



1 -383 



„ 0-46 



Palladium sponge 



1-562 



1 -497 



1 237 



1 -252 



„ 0-33 





1 -541 



1-476 



1-216 



1-231 



» 0-31 



Platinum foil and leaf . 



1-489 



1-430 



1-164 



1-185 



„ 0-26 





1-492 



1-428 



1-167 



1-183 



„ -26 





1 -490 



1-428 



1-165 



1183 



„ 0-26 





1-494 



1-426 



1-169 



1-181 



„ 255 



Carbon (mean of A 













and B) 





1-425 





1-180 





In the case of the cadmium cells, the E.M.F. rises with the 

 solution-strength as it does in the copper cells, and more rapidly 

 because K 2 is positive and also rises ; but in the case of the zinc cells, 

 the E.M.F. falls as the solution-strength rises, because K 3 is here 

 much smaller with the stronger solution. 



Cells Set up with Ammoniacal Solutions as Electrolytic Fluids, and 

 Electro- copper as Oxidisable Metal. 



It was found impossible to keep any one cell of this kind under 

 anything like constant conditions as regards the nature of the fluid 

 on account of the loss of ammonia, experienced to a large extent 

 even when covered with a jar, &c. ; accordingly, the following values 

 can only be regarded as approximate, especially in the case of the 

 stronger solutions. The strength of the fluid was ascertained by 

 sampling and analysis from time to time, and consequently inter- 

 polation was sometimes requisite in order to reduce the values 

 obtained with different sets of plates to the same mean strength. On 

 the whole, however, the figures indicate that with solutions of pare 

 ammonia, the E.M.F. rises with the strength of the solution ; and 

 similarly with liquids containing sal-ammoniac as well. 



