The effects of substituents and their positions in pyridine rings on the properties of electroplated nickels were studied. The crystal microstructure, brightness, cracks, and hardness of deposits obtained from Watts bath containing 24×10^-3mol/l of saccharin and 10^-3 or 10^-4 mol/l of pyridine derivatives were explained. When the electrolysis was carried out at a current density of 2 Amp/dm² in the presence of 10^-4mol/l of pyridine derivatives, the following results were obtained: The deposit obtained from the addition of 3-aminopyridine or 3-cyanopyridine was laminar and bright, while that obtained from the addition of 3-methylpyridine, 3-hydroxypyridine, or 3-pyridine carboxylic acid was columnar and dull. The deposit obtained from the addition of 3-pyridine carbaldehyde was granular and semi-bright. The decreasing order of hardness of the deposits obtained from the addition of these 3-substituted pyridines was as follows: cyano>amino>aldehyde>hydroxyl>methyl>carboxyl. The microstructures and brightnesses of the deposits obtained from the addition of 2-, 3-, and 4-aminopyridines were similar one another. The hardness of the deposits obtained from the addition of these aminopyridines was arranged in decreasing order of 2-≥3->4-. No cracks were observed in the deposits mentioned above.

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An investigation was made on the pretreatments for metal finishing with an emulsion obtained by copolymerization of methyl and butyl methacrylates in the presence of an anionic surfactant in an aqueous medium using no ordinary radical initiators. By dipping steel plate, previously coated with phosphate by conversion treatment, into the emulsion, its corrosion resistance and the adhesion of paint film to the steel were improved. The adhesive strength of paint film depended on the kind of emulsions used, especially on the structure of the copolymers. The emulsion of tert-butyl methacrylate copolymer showed much better effects than that of sec- or n-butyl methacrylate copolymer. The difference amoug the three emulsions in metal finighing effect was discussed in terms of the interaction of alkoxyl groups of the copolymer with film-forming components of the coating material.

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The effects of chloride on chromium deposits in low concentration CrO₃ bath (CrO₃ 50g/l, H₂SO₄ 0.5g/l, and Na₂SiF₆ 0.5g/l) and its removal were investigated, and the following results were obtained. When copper was a substrate, parts of no plating due to low current density were corroded at 10mg/l of chloride concentration. The area of the corroded parts was enlarged when the chloride concentration was higher, and finally, bright chromium plating was not obtained at a chloride concentration of higher than 30mg/l. However, in bright nickel plating, the covering power was not much decreased up to 100mg/l of chloride concentration and the corrosion of substrate and decrease of brightness were not observed. The chloride in the chromium plating bath was oxidized at anode and removed under ordinary plating conditions, and also it was proved to be removed by the addition of lead peroxide, which would suggest that the chloride mixed in the plating solution was decomposed by the lead peroxide produced at anode during and at a standstill of plating operation so that it was not a very harmful impurity unless its presence was in too much quantity for a while.

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Oxidation of aluminum was carried out with anodizing current of various electric wave forms in 250g/l maleic acid containing 3-4g/l H₂SO₄.
The coatings obtained with low ripple percent wave forms such as direct current and three-phase full-wave were uniform in thickness and color. The higher ripple percent wave forms were apt to cause the abnormally grown multiple layers and the burning. In the case of single-phase half-wave having the highest ripple percent, the abnormally grown multiple layers were easily formed at the early stage of anodizing and the uniform coating was never obtained.
The deepness of color and coating ratio were affected by H₂SO₄ concentration and current density, and the color became deeper and the coating ratio increased with the increase of ripple percentage. The hardness of the uniform coating obtained was in the range of Hv(0.05)521 to 537 which was much higher than Hv(0.05)449 of the hard anodic coating obtained in 0°C 15% H₂SO₄.

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The authors investigated the effects of ammonia concentration on gas nitrosulfidizing of iron and steel at 570°C for 120min. in the atmosphere of mixed gases composed of a carrier gas, H₂S, and NH3. The amount of nitrosulfidizing (weight increase during this treatment) was lager with the increase of ammonia concentration. The hardness of cross-section obtained at 30-50% of NH₃ concentration was similar to that obtained by nitriding treatment. It was confirmed by X-ray diffraction and EPMA that the surface layer obtained at 10% of NH₃ concentration was mainly composed of FeS; and it was composed of FeS, Fe_1-xS, FeN₃, Fe₄N, etc. when obtained at 30-50% of NH₃ concentration.

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