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ROYAL SOCIETY OF CANADA 



effect, attains a potential of 160 millivolts below that of the outer, 

 while with copper the corresponding value is 73 millivolts. If then 

 we suppose the two " effects '^ to act concurrently, the final readings 

 observed with the zinc and copper cylinders will represent their 

 algebraic sum. Denoting the metal effect for zinc by x and that for 

 copper by y and the Volta effect for the two metals by Y, \\e have 



from which we obtain the values 367 and 377 millivolts for the contact 

 difference of potential for the metals zinc and copper, an agreement 

 sufficiently close to confirm our hypothesis. 



Similar measurements have been made with all combinations of 

 the metals aluminium, zinc, lead, tin and copper, taken in pairs, with 



3 



5 



uniformly close results, the volta effects obtained in this way being 

 in every case proportionately less than the generally accepted values. 

 As an additional illustration of these measurements, the curves 

 representing the results obtained with an inner cylinder of lead and 

 an outer of each of the metals are shown in Fig. IV. Combining the 

 limiting potentials of these with the metal effect for lead, 216 milli- 



