A series of comparison tests was carried out on the degree of color change. That is the comparative test of the changing color between the alloys electro-deposited in aqueous solution from five kinds of alloys of In-Pd-Cd system, In-Al-Zn system, In-Cu-Zn system, In-Cu system, and In-Zn-Cd system, and the alloys composed of respective elements. The result is as follows,
i) In-Pd-Cd system is the most stable and the color does not change. On this point, much difference between the deposited and alloyed metals is hardly seen.
ii) The permissible extent for the composition of Cd and Cu is below 4 percent. If it is over 4 percent, the color of the alloy changes to black.
iii) It is most desirable that the permissible extent for Zn is below about 4 to 6 percent in In-Al-Cu-Zn system as for Cd and Cu. Aluminium in the above alloy systems can hardly be deposited by electroplating, therefore, aluminium itself has nothing to do with change of color.
iv) When In-Cu sysem and In-Zn-Cd system is used, the degree of change of color depends upon the amount of In added. The more the amount of In increases, the more decreases the degree of change of color.

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The mechanism of tungsten plating was investigated and the following results were obtained.
1) The decomposition potential of tungsten in Na₂WO₄ solution is more negative than that of hydrogen, and its accurate decomposition potential could not be obtained from its current density potential curves. Of course, its decomposition potential differs according to the kind of cathodic metals.
2) In the constant current density electrolysis, the cathodic potential is elevated with the progress of the electrolysis.
3) In the constant potential electrolysis (e.g. 0.124V for Pt-W poles), a beautiful deposition of whitish grey metalic luster is obtained, with a little higher potential (e.g. 0.184V for Pt-W poles) a reddish brown metalic luster, and with a much higher potential black and spongy. With the lower potential, nothing is obtained but the generation of hydrogen.
4) By the electron diffraction analysis, it is found that the whitish grey metalic deposition is chiefly composed of W-oxide (not WO₂ or WO₃) with a little metalic tungsten.
5) When the Na₂WO₄ solution is electrolised, the tungsten becomes special cation of its oxide. When the solution is electrolysed with constant cathodic potential, the tungsten is regularly obtained as metalic deposition on the cathode. This deposition is chiefly composed of lower oxide tungsten (such as WO) containing a little tungsten. So, the resistance increases and the potential is elevated with the progress of electrolysis.
As the potential is gradually elevated, the deposition grows rich in higher oxide and finally becomes to be spongy.
After all, it might be concluded that, in order to obtain thick deposition from Na₂WO₄ solution, the amount of metallic ions in the solution is to be restricted and hydrogen ions increased, or some other reducing regents more powerful than hydrogen are to be used, or the alloy-plating is to be applyed.

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This is a study on the comparison of lead enamel and lead free enamel which were patented in foreign countries, and borosilicate enamel which has been newly invented by us. The problem of pre-treatment of aluminium plate is also considered. The result is as follows;
(1) By conventional method, alluminum plates are treated with solution of caustic soda and potassium chromate before snamelling, and then oxide film is made on the surface of the plates. But this film is not satisfactory concerning adherence and gloss.
In our experiment they were treated with 3-5% solution of sodium perborate, keeping A.C. at 100V, and bath temperature at 45-50°C, for 5min., and the film of γAl₂O₃ was formed by anodic oxidation.
(2) Lead enamel showed better results than iron enamel. The former also had higher workability.
(3) Lead-free enamel showed similar results to those of iron enamel in shock and bending test, but in corrosion test it was found to be inferior.
(4) Borosilicate enamel showed about the same or better results as iron enamel in various tests, but was not so good in corrosion resistance. In luster, adherence and fluidity, it showed good results, and also had a strong point of easily handling.

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Observation of Microscopic structure of the cross section of bright copper deposits leads to the following conclusions:
Without brightener, the crystal mostly grows parpendicular to the base and the band structure does not appear, even though the periodic reverse process, periodic alternate current process, or periodic intermittent process is applied. With brightener, however, the band structure appear, especially when each of the above processes is applied its clearness increases.
The effect of plating conditions on band structure is that the clearness increases with an increase of brighteners, free cyanide, potassium salt and C. D., which means alternate deposits of copper and brightener.
The appearance of band structure, however, does not necessarily bring about brightness. The band structure is nothing but a phenomenon caused by brightening action and the section of the bright deposit shows structure that seem to retard the growth parpendicular to the base.

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The corrosion of lead and its alloy anodes in nickel sulphate electrolyte with and without cobalt was studied for the electrolytic conditions as to the kinds of electrode, time, current density, bath temperature, concentration of cobalt, etc.
From the research, it was found that the presence of cobalt ion in nickel sulphate electrolyte lowered the anodic potential of lead, but the corrosion of lead anode was not reduced.
In 1938, M. Rey and others reported that the presence of cobalt in sulphate electrolyte very much reduced the corrosion of lead anode. But it seems that the effect of the presence of cobalt does not necessarily reduce the anode corrosion depending upon the electrolytic conditions.

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