The current efficiency of a chromium plating bath containing fluosilicic acid more than its saturated concentration in chromic acid solution was somewhat higher than that in Sargent Bath.
However, platings of brighten and smoother in appearance were obtained under a wide range of plating conditions from the above plating bath.
Therefore, it was possible to obtain high speed chromium plating from the above bath under high current density.
Moreover, it was confirmed that this bath showed more excellent characteristics as follows:
1) Brighter and smoother platings were obtained under a wide range of plating conditions such as current density and bath temperature.
2) Deposits with no cracks were easily obtained and the number of pinholes was less than 1/cm² in the deposits of 1μ thick.
3) Deposits of about 50μ thick having hardness of Hv=1, 000-1, 200 were obtained from the bath containing up to 1g/l of sulfuric acid under a current density of 50-200Amp/dm² and at a bath temperature of 50-60°C. Their abrasion resistance was higher than that from Sargent Bath.

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The microstructures of unsealed anodic coatings of aluminum which had been oxidized by electrolysis in sulfuric acid bath and treated for coloring with aq. solution of various inorganic salts, were studied by means of an X-ray diffractometer and an electron microdiffractometer of high resolving power.
The experiments were conducted by the same processes an in the previous report. Aluminum had previously been coated with porous films by the electrolysis in sulfuric acid bath.
The results of the measurements of crystal structures of coatings under several treatments for coloring were as follows:
1) Peeled off films of unsealed oxide coating consisted of tetragonal lattices of γ-Al₂O₃, which had been slightly deformed from cubic system.
2) The oxide layer was changed to opaque grey film by the cathodic electrolysis in aq. solution of KMnO₄-H₂SO₄ and the formation of α-Al₂O₃ crystals was observed.
3) When the coating was immersed in aq. solutions of Co(Ac)₂ and KMnO₄, alternately, it was changed to brown colored, in which the precipitation of β-Co was observed.
4) When the coating was immersed in aq. solution of (NH₄)₂CrO₂, it showed light yellow color, and in some parts, it was observed to have slightly turned to crystallized structure from the ordinary amorphous state.

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The formation of oxide film on aluminum in oxalic and nitric acid was investigated by means of an apparatus consisting of a potentiostat and a high sensitive recorder.
The results obtained were summarized as follows:
1) In oxalic acid
(a) When the set potential was maintained at 2V in oxalic acid, straight lines having constant slopes were obtained during the period of electrolysis up to 6sec., which represented the formation of oxide films by ionic conduction. After the lapse of more than 6sec., the film was not changed to an insulating one; however, after 4min., the anode current began to be decreased and the compact film began to be formed again.
(b) When the potential was set at 1V, two straight lines having different slopes appeared at 6sec. of electrolysis. The film formed would be a complicated one, consisting of an ionic conduction film and an insulating film.
(c) When the potential was set at 0.7- -0.3V, each of the curves appeared in a similar type. That it; the ionic conduction film at the earlier stage of electrolysis was converted into an insulating film very soon.
(d) A1 P3 represented curves similar to that of the known high purity aluminum. Therefore, it would proceed in the same electrochemical process.
2) In nitric acid
(a) When the set potential was maintained at 2V in nitric acid, the anode current was rapidly increased with the lapse of time after the electrolysis of 1sec.
(b) When the set potential was maintained at 1V, the formation of film by ionic conduction was continued during the period of electrolysis up to 90sec., because the relation between log I and log T (T=√1+58.72t) was expressed by a straight line in this period. The anode current was increased with the lapse of time which showed that the dissolution of the oxide film occurred.
(c) When the set potential was maintained at 0- -0.3V, each of the curves appeared in a similar type, which was nearly the same as the result in 1) (c).
(d) A1 P3 represented the same current-time curves as those in 1) (d) so that the same electrochemical process of film formation would proceed.

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Electrochemical buffing is a combination of a conventional buffing and electrochemical dissolution of metals.
This paper describes buffing ability of soft steel electrolyzed in the electrolyte of NaCl aqueous solution.
The following results were obtained
1) Buffing ability in electrochemical buffing was higher than those in conventional buffings, and it depended upon the pressure in buffing and current in electrolysis.
2) The higher ability in the buffing would be due to the promotion of buffing efficiency by the rough surface produced in electrolysis.

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