1878.] 



Contact Theory of Voltaic Action. 



209 



of the table, strips of copper and zinc dipping into the vessel from the 

 binding screws ; these strips may have been of slightly different mate- 

 rial from the plates, that is, we are not qnite certain that they were 

 cut from the same sheets. In all subsequent experiments, the strips of 

 metal in contact with the liquids were cut from the plates themselves. 



Table VII.— 13th March, 1876. Plates 10 mm. apart. 

 Zinc and copper plates connected by the acid solution of zinc sulphate 



of Table YI at 17 

 Zero. 



1068 -0 

 68 -4 



65 -8 



66 -1 



67 -1 

 67 -1 



C. Zinc negative to copper, 

 Deflection. 



17-9 

 5-6 

 9-0 

 7-6 

 11 -9 

 4-9 



63 -0 

 61 -5 



61 -1 



62 -0 



63 

 64 



1085 -9 

 62 -8 

 74 -8 

 58-5 

 55 -2 

 72 



Cleaned the zinc strip. 

 50 -0 



70 -0 

 48 '5 



71 -0 

 53 -0 



72 -6 



13 -0 

 8-5 



12 -6 

 9'0 



10 -3 

 7 -8 



Mean. 



9'8 



Zinc and copper plates connected by dilute sulphuric acid, 

 negative to copper. 



Zinc 



Zero. 



Reading. 



Deflection. 



1069 -5 



1057 I 



12 -4 



68 *8 



76 -4 



7'6 



68*2 



62 '0 



6-2 



68 -0 



73 '9 



5-9 



68 -2 



62 -2 



6-0 



68 -0 



73 '2 



5-2 



67'0 



61 -9 



5-1 



66-2 



68 -9 



2 7 





Cleaned the zinc strip. 





61 -3 



51 -0 



10 -3 



62-1 



70 I 



8-0 



63 -0 



55 -0 



8-0 



63 -4 



68 -0 



4-6 



63 -0 



56 -0 



7-0 



62 -2 



67-3 



5-1 



The mean deflection for zinc and copper contact at 10° C. being 37*1. 



