28S Scientific Proceedings, Roy at Dublin Society. 



the process was repeated, and 40 minutes were now allowed for recovery. 

 The cell was again short circuited for 3 minutes, and the recovery observations 

 taken. 



When it is borne in mind that the sensibility of the method of observation 

 was O'OOl per cent., the correspondence to the linear relation is remarkable. 

 There does not seem to be any correction required for slow rise, as in the case 

 of the Leclanche cell. A deduction of 00008 per cent, from the observations 

 in set II before taking the reciprocal was found to be an improvement ; but 

 as this lies within the range of experimental error, no great reliance can be 

 placed on it. A single process would thus seem to govern the recovery of the 

 cadmium cell from polarisation. Its existence alone yields strong support to 

 the physical reality of the analysis we have made of the recovery of the 

 Leclanche cell. 



Conclusion. 



The study of the recovery of the Leclanche cell from polarisation has 

 shown that it may be divided into two sections : an initial stage of rapid 

 recovery in which almost 90 per cent, of the polarisation disappears in about 

 10 minutes ; followed by a slow return, extending over several hours, to the 

 initial value of the E.M.F. 



The initial stage can be represented by an equation of the type, 



(P.- ry-at+(r.- r y\ 



where V represents the E.M.b". of the cell at any time t. This equation 

 shows that the decay of polarisation is governed by the same law as the 

 decay of ionisation in a gas. It may be put into the form expressing 

 the velocity of a bimolecular reaction, 



%—ir.-rr. 



A similar relation has been shown to apply to the polarisation of the 

 Weston cadmium cell, and seems to account for the whole process of the 

 disappearance of the polarisation. This is independent justification of the 

 physical significance of the analysis of the recovery of the Leclanche cell, 

 and leads to the expectation that the law may apply generally to all types 

 of depolarising electrodes. 



The discussion of the theoretical interpretation of this result, and of its 

 application to the phenomenon of over-voltage, and other associated 

 questions, is reserved for a subsequent paper. 



