The nature and the degree of passivation of iron in 1 N Na2S04
was studied using the photoelectric polarization method. The shift
in composition of the oxide from the stoichiometric composition
Fe304, in the domain of active dissolution, into the y - Fe203 form
by oxygen adsorption favors passivity. The sorption of oxygen
leads to the decrease of the concentration of 3d electrons in the
oxide exerting an inhibitory effect on the dissolution of iron