1878.] 



Contact Theory of Voltaic Action. 



213 



made for each contact on the 14th of April ; as the solutions were 

 impure it did not at the time seem to be specially important to make 

 the experiments with greater accuracy. 



The insulated plates A and B were now cut, as they had hitherto 

 been rather near the sides of the porcelain vessels. It was not until 

 the 21st April that we could get a sufficiently large supply of pure 

 saturated solutions of zinc and copper sulphates. On Friday evening, 

 21 st April, we made our largest and most consistent series of observa- 

 tions. At no time since it arrived in Japan had the electrometer been 

 in such good working order, and, therefore, we shall take the results 

 of this evening, when possible, in preference to any others. 



Table X.— 21st April, 1876. Plates 10 mm. apart. 

 Latimer Clark's Cell. 



Zero. Reading. Deflection. 



1079 -0 1019 -5 59 '5 



72 I 1131 -5 59 -4 



73 -1 1014 -0 59 1 



74 7 1135-0 60-3 

 79 -1 1020 -6 58 -5 

 83 -5 1143 7 60 2 



85 -8 1026 -5 59 *3 



86 -0 1145 -5 59 '5 



87 -6 1028 -3 59 '3 

 86 7 1145 -5 58 -8 



Mean 59 A 



Assumed to be 1 "457 volts. 

 Direct reading 313 



Therefore ratio is — or 5 '27. 



59 -4 



Zinc and copper metallically connected. Zinc positive to copper. 



Zero, Reading. Deflection. 



1085 -8 



1054 -0 



31 '8 



86 -2 



1116 A 



30 -2 



86 -0 



1054 -6 



31 -4 



85 -8 



1115 -2 



29 A 



86 -0 



1053 -9 



32 -1 



85 -6 



1115 -5 



29 -9 



86-5 



1056 -5 



30 -0 



87 -2 



1116-6 



29 A 



Mean 30 "52 or '749 volt. 



