47 



of a wliite skin (probably of basio sail) wc have again examined 

 what influence this skin exercises on tlie phenomenon. For this pur- 

 pose the current was suddenly reversed, after a thick layer of the 

 basic salt had formed, in vvhicli however, only a cathodic j)olarisation 

 of 0,18 Volt was observed as a proof that this skin, indeed, increased 

 the resistance somewhat, as was expected, but that this could have 

 been only of slight influence on the amount of the anodic polarisation 

 tension ^). What the negative catalytic ii*ifluence here consists in, 

 cannot be said with certainty, but as has l)een stated, it seems 

 probable to us that the oxygen, dissolved in the metal to an exceed- 

 ingly slight degree, retards the setting in of the internal equilibrium. 



Iro7i. 



6. If we now proceed to the metal iron we meet again with 

 phenomena, and very pronounced ones too, which in our opinion 

 ))oint to catalytic influences. 



We found the following result : 



TABLE 7. 

 Iron electrode immersed in '/c N.FeS04-solution. 



from which it appears tliat in this transition of a current density 

 from 3(K) to 400 the iron has suddenly become very noble. This 



M For it can hardly be assumed heie tliat the slvin offers a difïerent resistance to 

 currents of different direction. 



