1493 
kh 7 1 (Fe) 
A = — | ln Ko + In ——— |. 
I K (Fe) 
from which it therefore appears that our formula differs from the 
so that according to equation (28) 
older one: 
Felt 1 (Fe 
ree (Ee) 
_ A 
Ff K We ) 
in this that here the term /n AY is wanting. 
This term, however, is very important because it appears from it 
that different unassarlable electrodes yet cannot give entirely the same 
potential difference, the electron solubility for the metals being different. 
By combining equations (26) and (28) we now get a relation for 
the potential difference, in which botb the metal ions and the electrons 
are taken into account. 
When we add these equations we get: 
hein | a In =| ae ea 
2 ue (1) 
That this new equation gives us a mueh better insight into the 
electromotive equilibrium than the old one follows already from this 
that it enables us immediately to derive the equation for the potential 
difference for the case that a metal is immerged into a perfectly 
pure solvent. 
In this case too metal atoms, metal ions, and electrons of course 
go into solution, and as in the metal and in the liquid the metal 
ions and electrons practically neutralize each other every where except 
in the border layer 
(Or) = (Mi) hen en ae RD) 
for this case where the metal ions and electrons originate exclusively 
from the metal, so that the equation for the potential difference 
becomes in this case: 
RT ] Ky 33 
NN ; = . . . . 5 
Ne Ty ” 
It follows therefore from this that the potential difference between 
a metal and e.g. pure water can be sharply defined and possesses 
a finite value which is entirely determined by the solubility of the 
electrons and by that of the metal ions. 
If the solubility of the metal ions is greater than that of the 
electrons, the metal will be charged negatively with respect to the water, 
and positively in the opposite case. 
96 * 
