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XLVI. The Reversibility of Voltaic Cells. 

 By T. Sidney Moore*. 



THE experiments described in this paper were carried out 

 in order to test the reversibility of certain voltaic cells. 

 Five cells have been treated: — Copper-zinc in sulphates, 

 copper-cadmium in sulphates, copper- zinc in chlorides, and 

 copper-cadmium in chlorides, in addition to the Clark cell. 

 Preliminary experiments were carried out with nitrate cells, 

 but the surfaces of the electrodes were spoiled by the nitrate 

 solutions, and these cells have been put aside. 

 The diagram of the apparatus is shown in fig. 1. 



Eto.1. 



ABODE F shows the ordinary potentiometer arrangement, 

 F being the experimental cell and E the Clark standard. 

 G is an adjustable resistance, and by means of its three-way 

 key H either the cell F may be placed in closed circuit with 

 G, or the accumulators may be opposed to the experimental 

 cell through the resistance Gr. 



By means of this arrangement it is easy to get two deter- 

 minations of the internal resistance of the cell F. Firstly, by 

 means of the direct current when the cell F is in circuit with Gr, 

 and, secondly, by means of the reading of the potentiometer 

 when a current is running through F and in opposition to it. 

 But to calculate the internal resistance from the latter expe- 

 riment it is necessary to assume that the experimental cell is 

 reversible. Thus, if we assume that the cell is reversible, the 



* Communicated by the Physical Society : read March 2nd, 1900. 



