660 
cules bound by an equivalent of an ion, is in many cases constant 
for the same complex former, 
If C,, the concentration of the complex forming molecules, is great, 
0.025 p? J 
the term Rr 1.117 D, C has less influence, and therefore the 
current tension line has a more normal course. 
Because the complexity constant in equation (16) only occurs in 
the term 0,058" log K, it seems that the complexity of the ion has 
no influence on the form of the line. This is only true for equal 
values of C,. For ions of different complexity C, will in general be 
different, and that greatest for the least complex ions. In consequence 
of this a current potential line of a less complex ion has a more 
normal course than that of an ion of greater complexity. 
The expression for the cathodic limiting current is the same as 
in the case of simple ions, namely : 
Ie 17 D,C 
drimit ES ai pds . . ° je . (1 7a) 
An anodic limiting current exists here no more than in the case 
of simple salts. According to equation (16) the greatest current 
density possible at the anode would be that for which: 
£ pdd 
EN 
as for a greater value of d the last term of (16) would become the 
logarithm of a negative value. For this current density equation (16), 
however, no longer holds. This case will be more fully discussed 
in a later chapter. de 
In Fig. 1 the line 6 is drawn for an electrolyte as Ag(NH,),, 
which is 0,1 n for the complex ions, and 0,001 x for NH,, e holding 
for the same electrolyte, but with O,l 2 NH,. This last line agrees 
pretty well in form with that for simple ions, a. 
3. Hydrated lons. The above derivations are, however, not 
quite complete. in so far as the hydration of the ions is not taken 
into account. 
That the ions in aqueous solutions are hydrated, may be assumed 
to be an established fact. Whether the water is chemically bound, 
or is carried along to join the movement of the ions in another 
way is an open question, which, however, is immaterial for this 
purpose. Nor is the number of molecules, carried along by = ye 
ferent ions, 5, accurately known. *) 
1 For a “summary of the present state of the problem of hydration see NILRATAN 
Drar. Z. f. Elektrochemie 2G (1914) 57. 
