The placer chromite in Hokkaido as the valuable resource of ferro-chromium and its dressing were studied. The small grains of chromite from the present deposit contain high percentage of Cr₂O₃ (63% Cr₂O₃ in the better grade) and little impurities. An example of the total analysis is as follows: Cr₂O₃ 54.391; FeO 24.28; Al₂O₃ 4.14; CaO 7.21; MgO 5.37; P trace; S 2.116; SiO₂ 0.35% .Dressing test by means of jigs revealed excellent results.

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A new theoretical consideration was made on the effect of various gases upon the microstructure of cast iron. A well-known phenomenon such as inverse chilling or abnormal crystallization, which has been never made clear by the so-called nucleus theory, may now be explained by the idea that oxygen dissolved in the molten cast iron disturbs graphite in its crystallization. In this case the oxygen is so apt to be adsorbed on the surface of graphite that its checking effect on the crystallization is extremely conspicuous, even though the concentration of oxygen is very small, only up to 0·001-0·01%. For instance, the "heredity" of pig iron, the complicated effect of superheating, slag, or atmosphere, or other unexpected phenomena which are often experienced by foundrymen, may probably be accounted by the fact that the oxygen has marked effect upon the separation of graphite from molten iron.
The solubility of oxygen in the molten cast iron is controlled by the concentration of silicon, being inversely proportional to √[Si]. From this relation we can calculate an approximate value of oxygen solubility. It is, further, noted that addition of small amount of Al or Ti has only a little effect on the oxygen solubility. On the other hand, with increasing temperature, the deoxidizing action of silicon becomes gradually weaker and hence the oxygen solubility in cast iron is favoured with the rise of temperature. It is due to this fact that superheating results in refinement of graphitic microstructure. Here too, it should be notcd that, as to the oxygen solubility, there exists a critical temperature above which the deoxidizing action of carbon becomes superior to that of silicon and the oxygen content begins again to decrease.
The oxygen content is, furthermore, governed by the composition of slag in such a way that the more acidic the slag, the smaller the oxygen concentration. In other words, cast iron molten under the strongly basic slag absorbs much oxygen and is liable to undergo abnormal crystallization. The "heredity" of pig iron is also attributed to the difference in oxygen content which results from the difference in the temperature and nature of slag in the blast furnace.
On the other hand hydrogen and nitrogen do not exert so much influence as oxygen, because, at the temperature of molten cast iron, they are hardly subjected to adsorption with graphite.

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The authors studied on physical and chemical properties of cast irons with 0·2-4·9%, Cu which have been made by alloying ferro-copper. With mofe than 1% Cu, the graphite of the cast iron becomes refined and the combined carbon increases, dendrites develop, and the peatlite changes into sorbite. The cast iron from cupolas superior to that from eleetric furnaces in its mechanical ploperties, In either case, the inorease of the Cu content acconpanies the rise of hardness. Maxima of tensile, transverse and compressive strengths are attained at 0·5% Cu, but excess of the Cu decreases the strength. Impact value somewhat lowers with the increase of the Gu, while figures pertaining to bending and compression hardly suffer any change. Results. of the dry-method wear-resistance test show no visible change, but the wet-method wear-resistance beeomes abruptly worse with more tban 1% Cu. The cast iron with 0·5% Cu is sufficiently resistant to any of hydrochloric, sulphuric and nitric acid. In every respect of properties, the 0·5% Cu cast iron develops the most excellent properties, and, above all, strength 10% more than the common cast iron and better corrosion resistance. When compared with Nickel-chromium cast irons, the Cu-bearing cast iron reveals lower hardness, higher strength, equal wear resistance and superior corrosion resistance. Copper cast irons of the present grade are suggested to be used as substitute for Nickel-chromium cast irons, indicating a tendency of high grade cast irons developed during the war.

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Two steel ingots were taken from each of the three kinds of steel melts of the basic open hearth furnace, to investigate the mechanical properties of axles subjected to different methods of working. Comparative experiments were made on the three kinds of axles made from the three kinds of steel melts such as axles directly forged from the steel billets, that with the central and neck parts forged from the steel bar and that as directly machined from the bar. It was found from the result that there is no remarkable difference among the mechanical properties of axles as far as an excellent steel ingots from the one and the same steel melts and as far as there is little difference in the temperature of heat treatment. Therefore it become distinct that any method of working axles will reveal the same characteristics as far as an excellent steel ingots are used and as far as the last stage of heat treatment is performed suitably.

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Heretofore the chemical analysis of the silicon in iron and steel has been limited to the weight analysis alone which is not suitable for the rapid determination. In view. of this point, the authors began to study a method of the rapid colorimetric analysis. From the result of experi ments on cast steel with the Leitz's triple colorimeter, the precision grade was found to be equal to the weight anaiysis as well as the time required became about one-third of the time in the latter method. Gist of the method of analysis is as follows:
2·5g of the sample was dissolved in the nitric acid (1·2), the solution of which was heated and added with a little excess of the saturated solution of potassium permanganate_by dropping and heated for morethan 10 minutes. The solution was added with a small quantity of anhydrous ferrous sulphate, decomposing the permanganic acid. The solution of ammonium nitrate and ammonium molyb. date was added to the mother liquor, from which the phosphor. precipitates by shaking. The mother liquor was again cleaned by filteration and the filterate was diluted into 250cc, of which 10cc is extracted into the colorimetric tube. A little excess of the emulsion of zinc oxide was added thereto for neutralization, the excess portion being dissolved by dropping of sulphuric acid (1:5). Hydroquinone (5% solution) was added to the solution, which was left behind for several minutes and then added with a solution of sodium sulphite in the sulphurous acid water, making a total volume of 30cc. The. final solution was heated in the water bath, when the silicon revealed a distinct blue color in the solution. The blue solution was cooled by water, and transposed into one of the glass cells of the colorimeter, while the other cell was filled with the "comparative" solution, which had been obtained in the same treatment from the sample with the known silicon content. In controlling the liquid level of both cells by upward or downward movement of the glass lever, the silicon content wae calcnlated by reading the ecale when the two colors became equal.

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Good results were obtained by applying the following method on the determination of tungsten in wolframite and ferro-tungsten. The procedure:-
0·5g of the finely pulverized sample of wolframite or ferro-tungsten was weighed and fused with an alkaline fusion mixture (K₂CO₃ 7g+KOH2g+KNO₃ 0·2g)in a nickel crueible. After the melt had been leached with the warm water, a little quantity of H₂O₂ was added by dropping to precipitate the soluble permanganate. Then (NH4)2CO3 was added and the solution warmed to precipitate the greater portion of the soluble silicate. The precipitate was filtered off and the filter was made slightly acid. The hydrochloric acid solution of cinchonine was added to the filterate to precipitate tungsten practically perfect. The precipitate was filtered again, ignited and finally weighed as WO₃.

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