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Prof. R. B. Clifton on the [June 14, 



If the potentials of the different substances in the voltaic element 

 just mentioned be represented by lines drawn perpendicular to an axis 

 along which the substances are distributed in the order in which they occur 

 in the element, the zinc being furnished with a copper terminal, the dis- 

 tribution of potential, when the circuit is not completed, is represented 

 by fig. 2. 



Fig. 2. 



Copper. Zinc. Water. Copper. 



As I have not yet obtained sufficiently trustworthy measures of 

 the difference of potential between zinc or copper and liquids, this 

 figure and those which follow do not represent quantitative relations ; 

 the zinc-water difference of potential C D may possibly be represented as 

 too large, compared with the zinc-copper difference of potential A B. The 

 figures are merely intended to represent the distribution of the potentials. 



Similar experiments were performed with zinc and copper plates dip- 

 ping in dilute sulphuric acid (1 volume of acid in 20 volumes of distilled 

 water), and with the same result, viz. that the zinc and copper plates 

 are, as far as can be observed, at the same potential ; and in this case, as 

 the experiments previously described show, the liquid is very nearly at 

 the same potential as the immersed metals. 



It is possible that with more dilute sulphuric acid Professor J enkin's 

 statement will be found to be absolutely true, the zinc, copper, and 

 dilute acid in which they are immersed being all at the same potential ; 

 but with the dilute acid used the distribution of potential in this voltaic 

 element is represented, in the same manner as before, by fig. 3. 



Pig. 3. 



Copper. Zinc. Dilute sul- Copper. 



pliuric acid. 



The series of metals and liquids which I have examined is small; but, 



