299 
Then the NiCl, solution was heated for some time in a hydrogen 
atmosphere with finely divided Nickel that had been prepared by 
reduction of NiO at relatively low temperature, after which the experi- 
ment was repeated. As the following photo shows (fig. 2), the pheno- 
menon had now entirely disappeared. 
3. df was already pointed out in the preceding communication, 
that as it were, the reflected image of the phenomenon was to be 
expected, when e.g. iron immersed in a ferro-ferri-salt-solution is made 
1. he 
cathode. The ratio ( will be greatest at the iron surface, because 
the iron by sending Fe'’-ions into solutions, strives to bring such a 
change in the boundary layer that in case of unary behaviour, it 
can be in equilibrium with it. Hence the farther the liquid layer is 
(Fe) 
He) 
iron, immersed in the supposed solution, is made cathode for a 
moment, the iron will be deposited from the boundary layer, and 
the ions from the following layer will diffuse into the boundary 
(Fe) 
(Fe) 
iron after cathodic polarisation comes “in contact with a liquid layer 
When therefore 
from the iron, the smaller will be the ratio 
layer, and as the ratio is smaller in this following layer, the 
in which the ratio a is smaller than before the cathodic polari- 
sation, which causes a stronger disturbance in noble direction, hence 
a less negative potential. After interruption of the current the said 
ratio will now increase again through the solution of the iron, so 
that the potential of the iron becomes again more negative. As on 
cathodic polarisation the iron gets covered with a layer of iron, 
which at first deviates from the unary iron in base direction, a 
phenomenon after cathodic polarisation was really to be expected 
also here, which would have to consist in this, that after interruption 
of the current the potential of the iron, after cathodic polarisation, 
passes through a maximum value. *) 
As the photo on fig. 3 shows, this supposition is confirmed. The 
maximum B lies about 30 m.V. less negative than the initial potential 
indicated by the line DE. 
It will now be examined whether the same phenomenon can also 
be observed for Nickel. 
Laboratory for General and Anorganic 
Amsterdam, June 27, 1919. Chemistry of the University. 
1) Through diminution of the total ion concentration the potential becomes more 
negative in a small degree, so_that this circumstance still slightly counteracts the 
phenomenon under consideration. 
20 
Proceedings Royal Acad. Amsterdam. Vol XXII. 
