1888.] Development of Electricity by Atmospheric Oxidation. 191 



Mean E.M.P. of Cells set up with Electro-copper and 

 mH 2 SO 4 ,100H 2 O. 





m = 2'5. 



m = 10. 



Increment 

 with stronger 

 solution. 



Platinum sponge covered, with plati- 











num black 









780 







-636 







658 



022 



Platinum sponge : tliin layer burnished 









530 







0-517 







527 



-oio 



Gold 



0-496 







•506 



o-oio 





0-444 







•460 



0-016 





0-447 







•458 



o-oii 





0-445 







•458 



0-013 





0-449 







•456 



0-007 











•464 





Carbon (B) 









•446 









About 



•35* 





j 





About 



•25* 





Cells Set up with Dilute Sulphuric Acid and Amalgamated Zinc, Bright 

 Cadmium, and Silver Foil, as Oxidisable Metals. 



The value of K 2 , the effect of substituting amalgamated zinc for 

 copper, was found to be generally some 2 to 3"5 centivolts higher at 

 first than after standing awhile ; after one or two hours, the zinc 

 plates were generally more or less coated with minute bubbles of 

 hydrogen through local action, and then gave pretty constant readings 



Value of K 2 = effect of substituting other Metals for Copper 

 in 7nH 2 SO 4 ,100H 2 O. 





Zinc. 



Cadmium. 



Silver 



m = 2'5. 



m = 10. 



m = 2 -5. 



m = 10. 



m = 10. 





+ 1054 

 + 1 -033 

 + 1-045 



+ 0-978 

 + 0-962 

 + 0-970 



+ 0-731 

 + 0-705 

 + 0-720 



+ 0-742 

 + 0-709 

 + -725 



-0-29 

 -0-12 

 Abt. -0-20 



* The values obtained with silver aeration plates of all kinds were most irregular and 

 wanting in steadiness ; with spongy silver (both from acetate and from chloride) 

 numbers were obtained varying between - 28 and 0'43, in the majority of cases not 

 far from 0'34 to 0*36 ; and with foil and leaf, numbers lying between 0"17 and 

 0-36. 



