In order to observe the cathode behavior of the surface of aluminum treated by the mixed solution of TiO₂ and HCl, the cathode polarization potentials in various electrolytes are measured.
A series of experiments about four electrolytes CuSO₄, NiSO₄⋅(NH₄)₂SO₄, ZnSO₄, FeSO₄⋅FeCl₂, done by changing concentration, amount of buffer-and addition-reagents, and temperature of electrolytes, reveals that the potential is much affected by the stortage of Cu²⁺ and N²⁺, and that the solution temperature of 20°C is preferable.
When it is necessary to change the potential of the cathode surface, the reading of which generally lies betweem those of ordinary aluminum surface and FeCl-HCl solution, control of pH value and amount of addition of buffer and other reagents should properly be considered.

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The surface of cast iron can be protected by the film of aluminizing against the gases of sulfur compounds as H₂S, SO₂, CS₂ etc. and during the preliminary ca. 5 hours the speedy chemical changes has happen later the changes slowly proceed.
Furthermore, The author is going to make a test of the above mentioned gases against the cast iron surface trying the “silicon” film on it.

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In the previous report⁽¹⁾, we showed that the corrosive action of boiling 5% sulphuric acid on 20-27% chromium stainless steels containing 5% Ni, 1% Mo and 1% Cu suddenly increases at nearly 25% Cr and the steels containing less than 25% Cr have unstable acid resisting property in this acid.
Therefore, concerning 23% and 20% chromium stainless steel containing 5% Ni, 1% Mo and 1% Cu which suffer frepuently severe corrosion in boiling 5% sulphuric acid, we made researches on the effect of addition of seveal organic and inorganic acid pickling inhibitors in markets to the acid solution.
As the results, among organic inhibitors, “Henkel” and “Picknoc” inhibit comparatively well the corrosion with addition of more than 0.20% and “IBIT” more than 0.25%. “Rodine” inhibits remarkably the corrosion and stabilizes the acid resisting property of these steels with addition of more than 0.25-0.5% of it.
Among inorganic inhibitors, potassium chromate (K₂CrO₄), as anodic inhibitor, is most effective and inhibits perfectly the corrosion with a small addition of only 0.005% and the film formed on the surface of steels is perfect and stable, but sodium phosphate (Na₂HPO₄) has no effect. Both Sodium arsenate (Na₂HAsO₄) and Antimony chloride (SbCl₃), as cathodic inhibitor, inhibit the corrosion with addition of more than 0.5%, however, the film formed on the surface of steel is unstable. Zinc sulphate (ZnSO₄) has comparatively poor effect.
(1) Jour. the Metal Finishing Soc. 4 (1935) No. 4, p. 153

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Chromium plating baths that can rapidly deposit relatively thick coatings under commercial conditions are of particular interest at present. Fluosilicates have been known for many years to be effective catalysts in chromium plating solutions, and the solutions containing them have great advantages ovre the conventional baths containing sulphric acid. But, heretofore, the practical method of analysis of chromium plating solution containing fluosilicic acid and sulphric acid has been so for unknown. This report will show our method of analysis of the solution.

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