377 



electrode; nor is tins strange in tlie liglit of these considerations, 

 for the different metal electrodes will exert a diffei-ent catalytic 

 action on the establishment of the internal hydrogen eqtiilibrinm. 

 But -not on]y the nature of the electrode, but also the condition in 

 which a certain electrode is, will l)e of influence on the supertension. 

 A polished platinum electrode or a platininized platinum electrode 

 tlo not give the same result; in the latter case the supertension is 

 practically zero, which can be explained l)y the fact that the mnch 

 larger surface of the catalyst causes a rapid establishment of the 

 internal equilibrium, to which is added that the actual current 

 density is much stnaller than is supposed, exactly in consequence 

 of this lai'ger surface. Finally also the electi'olyte can exert influence 

 on the setting in of the internal equilibrium, and thus we see that 

 the polarization phenomena at gas-generations can be surveyed and 

 accounted for with all other electrolytic |iolarization phenomena 

 from the same point of view. 



Consider^ntmis in the liglit of the theory of phases. A so-called 

 unattackable metal as hydrogen electrode. 



In my preceding communication "On the Electromotive Behaviour 

 of Metals" ') I have already treated the unattackable electrodes and 

 their efficiency as gas-electrodes. In this 1 have demonstrated that 

 the result of these considerations can be given in a A, .«-fig. in a 

 lucid way. 



That a platinum electrode, immersed in an acid solution, and 

 surrounded by hydrogen of one atmosphere indicates the hydrogen 

 potential in correspondence with, this pressure, is elucidated by the 

 adjoined fig. 1, which holds e.g. for atmospheric pressure and con- 

 stant total- ion-concentration. 



Though the equilibrium-normal-potential of platinum is not known 

 to us in consequence of its great inertia, yet it may be said with 

 certainty that this potential of the equilibrium, if it could be mea- 

 sured, would be very strongly positive with respect to the hydrogen. 

 The concentration of the electrolyte r would therefoie practically 

 quite coincide with the axis for the hydrogen. With a view to 

 lucidity I have however purposely not made the point c coincide 

 with the H,-axis in this schematic drawing. 



Let us now imagine that a platinum electrode is immersed in 



') 1. c. 



