LEWIS AND JACKSON. — POLARIZATION ON MERCURY CATHODE. 407 



assumption that the current itself produces, either some substance that 

 catalyzes the electrolytic reaction, or some condition of the cathode sur- 

 face which aids the reaction, and that this effect is increased by increasing 

 the current and persists for some time when the current is diminished. 

 This is the very conclusion to which we have already been led by the 

 other phenomenon mentioned above. Whatever the true cause of these 

 two phenomena may be, it is in all probability the same for both. 

 According to the observations of Russ,* who investigated the reducing 

 power of the electric current when a number of different solid metals 



U I 



Figure 2. 



were used as cathodes, the cathode occasionally became "active," that is 

 to say, permitted with the same potential a much greater current to flow. 

 This " activity " appeared to be produced by the current, and more rapidly 

 the larger the current. While this is similar to the phenomenon we 

 have noted, we might expect a solid metal to suffer occasional changes 

 of surface, but it is hard to see how any peculiar condition could estab- 

 lish itself on a mercury surface and persist after the removal of its cause 



* Zeit. phys. Chem., 44, 641 (1903). 



