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of the supply of electrons. But above a certain current density, 

 which evidently lies very low, this is no longer the case, and the 

 nielal-surface will contain more hydrogen ions and elections than 

 corresponds with the internal equilibrium. In consequence of this 

 the potential difference, as appears from the formula 



RT , Kn (Hs ) 

 A = In 



F (Hl ) 



will be more negative than when iidernal equilibrium had been 

 established. Let us now suppose that the current density is continually 

 increased, the potential difference becoming continually more negative, 

 then at a given moment super-saturation of hydrogen will set in 

 in the metal surface, and at a certain degree of super-saturation 

 hydrogen will be generated as second phase. When the current 

 density is kept constant, the potential difference can now diminish 

 a little, but on increase of the current density the potential difïerence 

 will now also increase further, because, even when hydrogen 

 generation takes place, this process can yet be accompanied with an 

 increase of the concentration of the hydrogen ions in the surface 

 of the electrode, and besides because the formation of the gas 

 bubbles through the diminution of the surface of contact metal- 

 electrolyte, causes the current density to increase very greatly. As 

 at the momejit that the hydrogen begins to separate as second phase, 

 the metal surface contains moie hydrogen ions and electrons than 

 corresponds with the internal ecpiilibriuni, the potential difference 

 at his moment will be more strongly negative than corresponds with 

 the state of internal equilibrium, which is in accordance with the 

 above mentioned formula. This internal equilibrium sets in when without 

 passage of a current, hydi'ogen of a pressure of 1 atmos|)here is 

 conducted round the platinized platinum electrode. The difference 

 between this equilibrium potential of the hydrogen and the potential 

 difference, at which during the passage of the current, the hydrogen 

 begins to separate as second phase on the unattackable electrode 

 for the first time, is called ".mperteitsion". It is clear that in the 

 light of the newer views this phenomenon is not distinguished from 

 the phenomenon of the cathodic polarization in any respect. The 

 supertension of hydrogen is, accordingly, nothing but a consequence 

 of the retardation in the establishment of the internal equilibrium 

 during its electrolytic separation, and the supertension in case of 

 all the othsr gas-generations can be explained in exactly the same way. 

 It has been found that the amount of the supertension for the 

 same current density is still dependent on the nature of the metal 



