Corrosion of Iron in an H2S-CO2-H2O System: Composition and Protectiveness of the Sulfide Film as a Function of pH. By J. B. Sardisco and R. E. Pitts. Corrosion. Vol. 21, 350-354 (1965) November.
Discussion by A. K. Dunlop, Shell Development Company, Emeryville, California:
In the equation defining the protectiveness of a sulfide film grown at a given pH, it appears that the concepts of protection and protectiveness have become intermingled. Thus, the effect of film weight (thickness) on corrosion is appropriate for calculating the total protection offered by a film, i.e., the thicker, the better. However, this gives no information regarding the intrinsic property of a given film, its (specific) protectiveness, i.e., corrosion resistance imparted per unit of film weight. Since it is this intrinsic quantity which is of interest, a reformulation is required. A satisfactory formula is Equation (1),
