123 
behaviour between metals and non-metals. In this it is noteworthy 
that the difference in solubility between the positive and the negative 
ions for the elements with exclusively metallic resp. exclusively 
non-metallie properties, is so great as to justify us in taking only 
positive resp. negative ions into account in the coexisting solution. 
For the intermediate amphibious elements as lodine, Sulphur, 
Selenium, Tellurium, Arsenic, and Antimony the existence of posi- 
tive and negative ions also in solution, should certainly be taken 
into account to obtain a deeper insight, and here lies still an exten- 
sive field to be studied more closely, led by the more recent views 
about the electromotive equilibria. 
Polarisation for non-metals. 
When we indicate the non-metal by AN, we may represent the 
formation of negative ions by the equation: 
4 Nn + nv0EnN" 5 . . c ° . . (6) 
Applying the well-known thermodynamic derivation for the poten- 
tial difference, we get: 
RT K vot 
= — In 
oF” WD 
in which(N’,) represents the concentration of the negative ions in the 
B+ (2) 
phase of which the electrode consists, this may be either a gas, or 
a liquid, or a solid phase. Starting from the electron formula: 
RT ze K's (Op) (8) 
F (Or) 
which is general, because the electron is the common constituent 
part of all matter, we may substitute for (7) the value that follows 
from (6) for the liquid phase, applying the law of the chemical mass 
action; thus we arrive at the already known equation: 
rr K'(Na,) 
A= ln = 
nv F EN )r 
A= 
(9) 
In order to study the polarisation phenomenon we cannot make 
use of equation (9), but we can use the newer equation (7). To get 
a good insight into this question it is desirable that we indicate the 
equilibria in the electrode completely; accordingly we must also 
express the splitting off of electrons, and write therefore: 
< ae oe pv 
XN, ÄnN, + nrd, etn (Oa) 
and 
