8 
Transactions Texas Academy of Science. — 1908 - 1909 . 
The protected inactive spots and the active spots together, form lit- 
tle short circuited galvanic cells, and whenever the operating current 
is cut off, the action of these “cells” gradually “discharges” the 
protected spots, and thus the whole surface gradually becomes active 
again. This regaining of the active conditions takes place even with 
those salts which heretofore were thought to render the surface 
permanently passive — namely, hydroxides and chromates. 
In connection with this work the fact revealed itself that the 
action at the anode depends specifically upon the particular ion that 
comes in contact with the anode; every ion has a specific tendency 
to effect both metal dissolution and oxidation, but the ratio of 
these two tendencies differs with different ions. Some ions, such 
as chromation, iodation, hydroxylion, etc., have a much greater tend- 
ency to oxidize than to dissolve the metal ; while with chloridion, 
sulphation, etc., the reverse is the case. While the results are of 
more particular importance in connection with the problem of the 
details of interaction between a solution and a solid, they are also 
of importance in connection with the problem under discussion, be- 
cause whenever iron — whether passivized or not — is exposed to a 
salt solution, ‘ ‘ cells ’ ’ are formed between spots of different po- 
tential on its surface, particularly between the active and the inac- 
tive spots on a passive surface, and it is readily seen from the above 
that the result of the action of these cells depends upon all the 
specific anions present — naturally, also upon their relative propor- 
tions. Hence, when a solution contains many common ions, such as 
sulphation, chloridion, etc., which have a great specific tendency to 
produce metal dissolution and a relatively slight tendency to anodic 
oxidation, then the electrolytic action between different 'poles on an 
iron surface would be such that very soon nearly the whole surface 
would be rendered active ; while in the presence of ions of the op- 
posite tendency, the reduction of the oxide surface would take place 
very slowly, and a balance would finally be established between the 
rate of this reducing action and the rate of direct oxidation of the 
surface by contact with air, or with the salt itself if this is a chro- 
mate or iodate — i. e., a substance which is capable of oxidizing other 
substances. Hence, when such a substance as a chromate, etc., alone 
is present, it has been found that the corrosion of the iron did not 
proceed appreciably. However, when, in addition ions of a larger 
“metal-dissolving tendency” are present, then this inhibiting action 
of chromates, etc., may be more or less completely nullified — depend- 
ing upon the relative proportion between the different salts. 
Thus the final conclusion is plain — neither passivizing by any 
means whatever, nor the addition of “rust inhibiting” salts to a 
