Chemistry. — “On the Phenomenon after Anodic Polarisation.” I. 
By Prof. A. Smrrs, G. L. C. La Basripe, and Tu. pr CRAUW. 
(Communicated by Prof. P. Zeeman). 
(Communicated in the meeting of June 28, 1919). 
1. It was shown in a preceding communication that the 
phenomenon that appears after anodie polarisation of iron in an iron 
salt solution is owing to this that during the anodic solution the 
iron gets surrounded by a liquid layer which is very rich in ferro- 
sens 
é 
than outside it. After the current has been broken the ferri-ions will, 
e É : RE 
ions. As a rule the ratio Ee will be greater in this liquid layer 
therefore, diffuse from the surroundings into the boundary layer, 
(He) 
Fe”) 
to become again smaller in the boundary layer. In consequence of 
this change the potential of the iron, which was at first less negative 
or positive through the disturbance of the metal, passes-through a 
minimum value after interruption of the current. 
That the above explanation actually accounts for the phenomenon 
was proved by the fact that the phenomenon disappears altogether 
when the iron salt solution is previously heated in a hydrogen 
atmosphere with iron powder for some time. We then get a ferro 
salt solution which is in electromotive equilibrium with unary iron, 
Pe" 
whereas the ferro-ions pass outside, which causes the ratio 
Fes) 
change when the iron is anodically dissolved. 
so that in the boundary layer the ratio practically does not 
2. In the above mentioned communication it was pointed out 
that the potential of Nickel after polarisation in a solution of NiSO, 
likewise passes through a minimum value, so that it was already 
supposed that this phenomenon would have to be explained in the 
same way as for iron. 
To examine this the phenomenon for Nickel was first photographed 
when the metal was immersed in a solution of NiCl,. In this the mini- 
mum shows itself very clearly, as the adjoined photo (fig. 1) sets forth. 
The process is much quicker than when an NiSO, solution is used, 
in consequence of the positively catalytic action of the chlorine ions. 
