Alle japanische Sandeisenerze enthalten TiO₂ als Ilumenit in so kleiner Koernung, dass es auf uebliche Aufbereitungsweise nicht beseitigt werden kann. Daher hat der aus diesen Erzen durch Reduktion bei einer Temperatur unter 1, 100°C hergestellte Eisenschwamm auch noch soviel TiO₂, wie es schon in den Erzen vorhanden ist, was im Gefolge eine Herabsetzung der Qualitaet des Eisenschwammes bedeutet.
Der Verfasser hat sich mit einer Reihe von Untersuchung beschaetigt, um den obigen Nachteil zu vermeiden und ein Verfahren erreicht, aus den Eisenerzen, die etwa 58% Fe und etwa 13% TiO₂, enthalten, mit einem Eisenausbringen von etwa 82% Luppen herstellen zu koennen, die durchschnittlich folgende Zusammensetzung haben;
Ges. Fe C S SiO₂ CaO TiO₂
94%, 2·5-3%, <0·02%, <1·00%, <0·25%, <1·80%
Er hat zunaechst die obigen Eisensande, gemischt mit 10% Kohlungsmittel und geringer Menge Kalk, durch Koksabrieb bei 1, 100°C reduziert und dann auf 1, 400°C in demselben Ofen erhitzt. Die Beschickung ist infolge der letzteren Waermebehandlung in ein Gemisch aus Schlacken und TiO₂ freien Luppen uebergegangen, weil der Schwamm sich unter den obigen Bedingungen durch Aufnahme von C in Luppen umgewandelt ist und die sich im Eisenschwamm verteilten Schlackenbestandteile zugleich davon herausgepresst worden sind.
Man muss, um dieses Verfahren erfolgreich durchzufuehren, die Schlackenbestandteile so regulieren, dass die Menge von SiO₂ unter 30% von Schlacken bleibt.

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The author studied the vacuum extraction process for the analysis of hydrogen only, and succeeded in finding a process, using a simple and compact furnace and large specimens. He also found that the selection of specimens is important. The analysis of hydrogen was made by this process, whilst the analysis proposed by the 19th Divisional Committee of the Institute for the Promotion of Science and Technology ("Gakujitsu Shinko-Kai") was applied to nitrogen. Thus, the variation of the contents of hydrogen and nitrogen in the course of steel-manufacturing was investigated, and the measures for reducing such elements were considered.
The results of the experiments are outlined below:-
(1) In the acid open hearth refining, more hydrogen exists in the melting-down period and it is reduced at the oxydizing stage, whilst at the latter half period there is again a tendency towards its increase and the quantity rapidly increases at the killing period and after discharge. Nitrogen reduces while the steel is boiling.
(2) In the basic open hearth furnace, the quantity of hydrogen increases even in the oxidizing and boiling periods, whilst that of nitrogen is considerably reduced by the boiling action.
(3) In the electric are furnace, the variation of hydrogen is not distinct, but it increases in the reducing period and after being discharged.
(4) In each meting process, the quantity of hydrogen before casting is generally 4·5-7·5cc/100g (0·0004-0·0007%).
(5) The main cause of mixing hydrogen is due to gas, water, etc, which are contained in steelmaking materials, slag-making agents combustion gas, air, ladle and moulds. The boiling action is very effective for the extermination of nitrogen, but is not remarkable for that of hydrogen.
(6) In ingots, more hydrogen and nitrogen exist at the top and bottom, but less at the middle.
The difference is more remarkable in nitrogen.
(7) The hydrogen in steel diffuses even at a normal temperature. In the range below 1, 000°C, it is quickest at a temperature immediately below the transformation point.

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Various researches and discussions have hitherto been made for the problem of flakes, and also various schemes for the prevention of the generation of flakes have been proposed. It seems, however, that the problem is not yet completely solved. The growth of the flakes is not due to a single cause, but is related to the combined result of many factors. As the causes of the generation of flakes and their properties are different, the prevention should naturally be devised in accordance with this fact, so that the solution becomes very difficult.
In this paper, the author discusses mainly the steel-making process using a basic electric-arc furnace, and considers that the causes of flakes exist generally before the production of ingots Consequently in his view that the flakes are made by melters, the forging and heat treatment are not widely dealt with in this paper.
In considering the relation between each steel-making process and flakes, crucible and acidic openhearth furnaces are most insensitive for the growth of flakes, whilst basic open-hearth and basic electric arc furnaces are the most sensitive.
The problem is, howevere, solved by the lime process for acid open-hearth furnaces, whilst for basic open-hearth furnace, special processes such as the "duplex acidic and basic open-hearth process" are used in Germany and Austria. However, there is no distinct measures for basic electric-arc furnaces either at home or abroad.
The author examined this problem, and explains the steel-making process using a basic elecrtic arc furnace, with which the prevention of flakes was experimented. He hopes that the paper may become a reference to people engaging in the steel-making industry and may invite their discussions.

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In the majority of researches hitherto carried out for hardening liquid, the specimen was hardened in the liquid. and its cooling state was investigated by means of the cooling curve, etc. In the present research, however, the observation was directed to the liquid, and the condition of ejecting hot current of the liquid and that of the convection were photographed by Schrieren's Method, the results of the preparatory experiments having been published in the Journal of the Society of Mechanical Engineers, Japan in the names of Mr. Tachibana and the author. In the present paper, the results of research on the state of hot current at the instant of hardening, and the relation between the surface temperature of the specimen and the heat quantity lost in unit time, etc, are dealt with.

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Previously, the authors judged qualitatively the states of diffusion of various elements into molten carbon steel and nickel steel, and confirmed a considerable difference in diffusion, in accordance with the melting points of various elements and the alloy irons and the specific gravity, the temperature of molten steel, the duration of keeping a constant temperature, the magnitude of affinity of the elements and iron, etc. The present research was carried out for the further clarification of such relations, and a quantitative method by chemical analysis was adopted.
As to the experimental process, Swedish steel of 0·1-0·3%C was made to a cylindrical form of 100mm. in length and 22mm. in diam., as shown in sketch, and its bottom was finished semi-spherically corresponding to the internal diameter of a Tamman tube which melts the steel. The hollow parts A and B arranged at the upper or lower part have an internal diam. of 14mm. and a height of 10mm., the positions being changed from the previous case. In these hollow parts, the element or alloy iron to be tested is charged, and placing it in the Tamman tube, the melting was carried out by a Tamman furnace, and without stiring it a constant temperature was kept for a definite time, and it was then cooled gradually in the furnace.
When the specimen was cooled to a normal temperature, it was machined longitudinally from the side in parallel until the width became 15mm, and then hardness was measured along 20 lines drawn at an interval of 5mm, from the bottom, and also microscopic examinations of structures at several parts were made as required. Then, specimens were taken by machining it with a lathe at 2·5mm above and below the hardness measuring lines, i.e., at each width of 5mm. Chemical analysis was made with these specimens. The results of the experiments give approximately the same conclusion as that in the previous research.

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