706 



concentration kept artificially constant, Fig. I can account to us for 

 what will happen. 



If positive electricity is applied to electrode I, the electromotive 

 equilibrium is bioken for a moment, and a new electromotive 

 equilibrium sets in, in consequence of molecules of the metal I being 

 dissolved as positive ions. If the ions il/ " and J/,-- entered the 

 solution in the same ratio as tliey were present as njolecules in the 

 metal, the composition of the metal would not change while the 

 electrolyte gets richer in ^l/,"--ions. It is clear that as we now 

 exclude internal transformations, in this way there cannot be question 

 any more of a renewed setting in of the clectromotixe equilibrium. 

 If the metal-ions entered. the solution exactly in the same ratio in 

 which they are already present in the electrolyte, the concentration 

 of the metal phase would change, whereas that of the electrolyte 

 remained the same, which could not lead to a renewed setting in 

 of the electromotive equilibrium either. 



Thus we see that the metal phase will emit M" and J/,"--ions 

 in a ratio lying between L and S, in consequence of which both 

 phases become richer in M^, and two phases can therefore form 

 again, which can be in electromotive equilibrium with each other. 

 On supply of positive electricity to the electrode I the potential 

 difference A will, therefore, have to descend, and when the dotted 

 line pq in Fig. 1 indicates the potential difference zero, it is even 

 possible that the potential difference A at electrode I becomes negative. 



What will take place at the other electrode II? At this electrode 

 metal will be deposited, and it is easy to see that assuming that at 

 first the stable phase S separates, the different metal-ions will be 

 discharged in a ratio lying between L and S, because only in this 

 way a renewed setting in of the electromotive equilibrium is possible. 

 Hence the coexisting phases will become richer in M on the side 

 of the metal-deposition, and the potential difference will become 

 greater positive. For a definite potential difference indicated by the 

 line ce another metal phase d will arise by the side of the metal 

 phase e, and when the electric current continues to pass through, 

 the potential difference remains constant till the metal ions in the 

 electrolyte depositing on the metal phase e, have converted this 

 latter phase, at least superficially, into the metal phase d. Then the 

 potential difference can increase again, and the metal phase moves 

 along the line da and the electrolyte along ca. 



So we may conclude from the foregoing that when the current 

 has continued to pass for some time, figure 2 of the potential differences 

 may have been changed into figure 3. 



