The following results were obtained in the measurement of dragout of chromium plating solution. (1) The dragout of chromium plating solution was little affected by CrO₃ concentration under definite conditions of temperature and surface tension of the plating solution and the shape, size, and hanging and drawing up methods of the specimen. (2) The dragout of the solution was affected by the factors of W, W_D1, and W_D2 as follows: in which, W: The dragout published by Kushner, W_D1: The liquid remained on the lower side of specimen. and W_D2: The liquid film on the surface of specimen. The latter two values were obtained from the authors' experiments. The following relations were derived:
W=0.02A√Uφ/d
W_D1=(0.65±0.1)s/dgl
W_D2=0.001A
where A: Surface area of specimen (cm²), l: Length of lower side of specimen (cm), U: Velocity of drawing up (cm/sec.), φ: Viscosity of plating solution (poise), d: Density of plating solution (g/cm³), s: Surface tension of plating solution (dyne/cm), g: Gravitation (980 dyne)
(3) When W<W_D1+W_D2, no liquid drops remained on the specimen and the real dragout was expressed by W; and when W>W_D1+W_D2, liquid drops corresponding to W-(W_D1+W_D2) remained and the real dragout was expressed by W_D1+W_D2.

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Assuming that nC: CrO₃ concentration in chromium plating bath, V: Volume loss of the bath by evaporation, etc. in one day operation, v: Dragout in one day operation, and V₁: Capacity of rinsings-recovery tank, and supposing that the rinsing effect became worse when the concentration of the tank rinsings was higher than C, the rinsings should be used at concentrations of lower than C. When the operation was conducted so that the concentration of rinsings became just C after one day's work, the volume loss V would be recovered in the plating bath. In the following day's operation, the rinsings remained in the recovery tank was set just at the concentration of C, containing the dragout of CrO₃ from the plating bath; and the excess of rinsings was thrown away. In such a process, the CrO₃ concentration in chromium plating bath would be nC={V(2V₁-v)/2V₁v+1}C with no throwing away of recovered rinsings. The ratio of reduction of CrO₃ loss between chromium plating bath of low concentration and that of high (m times as high as) concentration was as follows:
R=1/m+2V₁V(m-1)/v(2V₁-V)≈1/m+V/v(m-1)
Since V<<V₁ in general, R will approximately be equal to the right. As the value of V/v is 2-2.5 in practical decorative chromium plating, the loss of CrO₃ will largely be reduced when the bath of low CrO₃ concentration is used.

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In the preceding paper, there were reported the plating methods of tin-zinc alloys from the baths free from cyanides and fluorides. It was found that low zinc content alloy deposits having good appearance were obtained from gluconate baths. In this paper, there are discussed some properties of tin-zinc alloy deposits obtained from gluonate baths; namely, effects of o-vanillin as a brightener, corrosion resistance, hardness, and whisker growth. The following results were obtained (1) The surface of a tin-zinc alloy deposit containing almost equimolar ratio between zinc and tin was smoother than that of single tin or zinc deposit: and the structure of the former was much finer than that of the latter. (2) The brightening effect of o-vanillin on the alloy plating seemed to be due to the crystal growth of tin, not of zinc. (3) The tin-zinc alloy deposits had high corrosion resistance and their sacrificial protective actions were retained in the range of 2-3% of zinc contents of the deposits. (4) The tin-zinc alloy deposits had high solderability and their hardness vas slightly higher than that of cast alloys. No whisker growths were found on their surfaces.

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Experiments were conducted to study whether copper-iodide complex solutions would be used as Strike Baths for steel. The suitable conditions of composition and operation of the bath were found to be Cu: 2-10g/l, KI: 160-400g/l, pH: 0-2, current density: 2-10Amp/dm². Lustrous and adherent deposits were obtained under these conditions. However, the current efficiency was low as less than 24%, because of low copper content of the bath. Copper or nickel was available for the anode, but the copper anode was apt to be passive. Therefore, the ratio of area between anode and cathode had to be kept larger in order to decrease the anodic current densities.

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The specimen surfaces bombarded with Ar⁺ ions prepared from OFHC, Nb base super-conducting alloy ingots and multi-layered magnetic alloys plated on thin wire of Cu-3wt % Ag alloy were observed mainly with optical and electron microscopes, interference microscope and differential interference microscope to discuss the distinction between chemical and ion etchings. The results of experiments were as follows: (1) In both of chemical and ion etchings of OFHC specimen, a clear step was observed between two neighboring crystal grains having different crystal orientations. In the chemical etching, no change was seen in the height of step with the lapse of time. (2) In the chemical etching, marks of slip lines, having been produced by plastic deformation, were too indistinct to be observed. While, in the ion etching the marks, having be lessened by electropolishing, reappeared. (3) Typical nodular structures were observed by chemical etching of Nb-base super-conducting alloy ingots. While, the nodular structures disappeared by ion etching, showing preferential removing of Zr and Ti from the alloy. (4) The multi-layered structure, mainly consisting of magnetic alloys, could not be clearly observed by the conventional chemical etching; but, it could be clearly observed by application of the ion etching.

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This paper describes the effects of oxide film, produced on the surface layer of steel, on wear. Stationary and rotary test pieces of S 45 C were treated with heated steam and were subjected to non-lubricated sliding wear under the conditions of oxidizing and adhesive wear to study the behavior of the oxide film to the wear. The test results showed that so far as oxide film was present on the sliding surfaces, the metal transfer from the other test piece hardly occurred irrespective of wear conditions so that high wear resistance was observed. However, when the fragments of film were interposed between the slideng surfaces by the failure and dropping out of the film during the course of wear, another wear caused by the scratching and ploughing rapidly increased the amount of wear. The drop-out of oxide layers was larger on the sliding surfaces of both of stationary and rotary test pieces with oxide layers as compared with the surfaces of stationary test pieces only with oxide layers. Therefore, a sufficient wear resistance was not achieved in the former case. The conditions of the steam treatment for improving the wear resistance of steel was at 600°C for 2hrs. in the range of these experiments. When it was treated at a lower temperature, the film produced was too thin; and when treated at a higher temperature, the dropping out of oxide layer was observed immediately after the treatment. The both cases were found to be improper for the purpose of improving wear resistance.

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Reduced Ni films, deposited from an electroless plating bath containing BaBH₄ as a reducing agent, consisted of nebular crystals, which were aggregates of fine microcrystal particles. These particles were arranged in random orientations or in a definite orientation as single crystal films, according to the plating conditions. This paper describes as follows: the quantity or reducing agent in the plating bath had effect on the arrangement of these crystal orientations, and the crystal orientation of fine microcrystal particles depended on that of Cu substrate. The orientation relationships between the Cu substrate and reduced Ni films were as follows: 1. {100}Cu||{100}Ni [020]Cu||[020]Ni, 2. {110}Cu||{110}Ni[020]Cu||[020]Ni, 3. {111}Cu||{111}Ni [220]Cu||[220]Ni

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