1486 
gives rise, both with regard to the reactions which can take place 
between a metal and an electrolyte, and to the potential difference 
metal-electrolyte, have been derived, will the phenomena of polari- 
sation and passivity for this simplest case be discussed. 
Thus the whole will constitute an introduction to the more thorough 
treatment of the other cases, indicated by equations (2) and (3). 
2. Solubility product of a metal. 
The new views which will be developed here, are based on the 
assumption that the electrons in a metal phase and in the coexisting 
electrolyte behave as ions, so that the laws which hold for mole- 
cules and have been successfully applied to ions, can also be trans- 
ferred to the electrons. 
Let us now consider the simplest case, namely this that exclusively 
the ionisation equilibrium 
MM +26 
exists in the metal J/. 
If we now immerge this metal in pure water, uncharged atoms, 
metalions and electrons will pass into the water with the result 
that an ionisation equilibrium is also established in this liquid. 
If we apply the law of chemical mass action to the above ion- 
isation equilibrium, which exists i the liquid, we get: 
Ee 
Now the liquid is in contact with the solid metal, so that the 
liquid will be saturate with respect to the non-electric component, 
the uncharged metal atoms. The concentration (M) is, therefore, a 
constant, hence we may write : 
KG = (MT) (Oh Mini evene eee (>) 
This product, which is, therefore, a constant quantity for constant 
temperature and pressure, we shall call the solubility product of 
the metal. 
The supposition that the complexity of a metal exists in the 
occurrence of metal atoms, metal ions, and electrons, which in case 
of unary behaviour of the metal, give rise to the existence of the 
ionisation equilibrium represented in equation 1, leads therefore to 
an important idea, namely that of the solubility product of a metal, 
by means of which a number of electromotive processes can be 
surveyed from one and the same point of view and can be accounted 
for in a plausible way. 
