147 
solutions of complex cyanides. Harer ') showed, namely, that when 
we wanted to attribute the metal deposition in these cases to direct 
discharge of the elementary metal ions, the velocity with which 
these are formed from the complex ions, would have to be exceed- 
ingly great, much greater than any known velocity. Hager, there- 
fore, assumes that the deposition of metal takes place, not by the 
discharge of the elementary metal ions, which are present in a very 
small quantity, but because the complex ions M(CNY, present in 
large quantities, combine with an electron, and split up into 
M and 2CN'. 
10. Polarisation during the electrolytic generation of halogens, 
oxygen ele, 
It has therefore appeared from what precedes that the ionisation 
or the splitting off of electrons is a process that proceeds compa- 
ratively slowly in some cases. 
Also in the electrolytic generation of the halogens, of oxygen ete., 
polarisation phenomena have been observed, which points to the 
fact that bere too relative retardations come into play. The electro- 
lytic generation consists in a splitting off of electrons, as the following 
equation indicates : 
GE cee Beret kA rade la” LO} 
And as for metals we are compelled to assume that the splitting 
off of an electron from a neutral atom proceeds comparatively 
slowly, it is natural to assume that the splitting off of an electron 
from a negatively charged atom does not proceed with an infinite 
velocity either, so that this process too can be relatively retarded 
for a definite current density. 
The concentration of the electrons in the liquid being exceedingly 
small, the generation of C/ will take place practically exclusively 
at the metal surface. We can now imagine that at the surface of 
the metal which is in equilibrium with chlorine and chlorine ions, 
the following equilibria exist: 
ACU 2Cl + 20 
Vt 
Cl 
When the splitting of chlorine ions in atoms and electrons at 
the boundary surface metal-solution is relatively retarded above a 
certain current density, the concentration of the chlorine ions will 
be too great in the boundary layer, and that of the electrons too 
small. 
1) Z. Elekr. 10 (1904) 433, 773. 
LO* 
