657 
of the velocity of stirring, when the stirring is equally vigorous at 
the cathode and at the anode. 
[t is, indeed, also possible to speak of an anodic limiting current, 
in so far as at a certain current density the concentration of the 
ions at the anode can become greater than that in a saturate solution 
of the electrolyte. In this case the electrolyte will crystallize out on 
the anode, on account of which the current will be broken, or at 
least weakened. 
As ta=2C for the cathodic limiting current, this crystallizing 
cannot take place when the original concentration of the ions in the 
solution is half that of the saturate solution. 
For small current densities : 
AE 0.025 J 
Rade tne Allie DC, 
So that for small current densities the current density for a given 
polarisation tension AZ is proportional to the concentration. 
On comparison of the course of this theoretical line with the expe- 
rimentally determined lines it appears that in some cases (nitrates 
and chlorates of different heavy metals) the course of the two lines 
agrees. In a great many cases the course of the real lines is, how- 
ever, different, namely so, that in many cases they are much flatter, 
especially in the beginning, about as the line 4 in figure 1. This is 
the case for solutions in which complex ions occur, also in case of 
hydrogen generation, and for metals that can show passivity. In the 
two last cases the divergent course does not lie in the value of c, 
but of ¢, so that they are left out of consideration. For the complex 
ion the current opinion is*) that the deviations are caused by a 
slow formation of elementary ions from complex or hydrated ions. 
This view rests chiefly on observations by Haper and Rrss*®) on 
reduction of organic compounds, and of Le Branc and ScmickK *) on 
the results of alternate current electrolysis in solutions of complex ions. 
Eucken *), however, has shown that though the complex ions 
rapidly split up into simple ones, the current potential line belongs 
to the type 5 and not to the type a of figure 1. 
The derivation which EvckeN gives, is pretty intricate, as he 
bases it on the supposition that the simple ions are formed with a 
(9) 
1) Cf. e.g. Foerster, Elektrochemie wässriger Lösungen. Leipzig 1915, p. 252 
et seq. 
2) Z. phys. Chemie 47 (1904) 257. 
5) Z. phys. Chemie 46 (1903) 213, Z. Elektrochemie 9 (1903) 636. 
4) Z. phys. Chemie 64 (1908) 562. 
42 
Proceedings Royal Acad. Amsterdam. Vol. XIX. 
