46 



served as. anode, was gradiinllj covered with a skin of basic salt. 

 It was, however, easy to demonstrate that this skin could not have 

 caused the observed phenomena throngli increase of the resistance, 

 for the phenomena remained the same also when this skin, which 

 could be vei-y easily removed, was taken away during the electro- 

 lysis. Moreover it appeared that when this metal with skin was 

 made lo cathode, the cathodic polarisation was the same as in the 

 absence of this skin. The foruuition of the skin is therefore a secon- 

 dary phenomenon, as was also expected (see under 1). 



Bmnuth. 



5. Bismuth is a metal that very clearly seems to be catalytically 

 influenced, as appears froui the following table. 



TABLE 6. 

 Bismuth in i'2 N Bl (NO;3)2-solution. 



The anodic polarisation presents this particularity that though it 

 is exceedingly small up to a current density of J 33 milli Ampères 

 per cm", as for silver, it becomes pretty considerable foi' a current 

 density of 260 milli Ampères. Now it is worthy of note that the 

 anodic polarisation was at first also small for a current density of 

 260, but it increased slowly, so that it amounted to -|- 1.14 volts 

 after a few minutes. For smaller current densities, however, no rise 

 of the polarisation tension took place in course of time. The explanation 

 of the observed phenomenon is probably as follows. The Bisnuuh, 

 which gets positively charged in the used solution, assumes internal 

 equilibrium very quickly at first. At the greatest density of current, 

 however, this internal equilibrium is no longer able to maintain itself, 

 and then generation of oxygen seems to take place, which oxygen 

 evidently exercises a negative, catalytic influence, which renders the 

 metal still nobler. This phenomenon being attended with the formation 



