By mearsuring gas contained in open-hearth slag, the relation of such gas and hydrogen content in molten steel is studied, and it is investigated that four kinds of gas, viz., H₂O, CO, CO₂ and H₂, are contained in the slag and maintain mutually a balance represented approximately by the following formula
CO+H₂O CO₂+H₂
H₂O contained in the slag is that which was absorbed from furnace atmosphere, in which 5-10% of water is usually contained. If boiling of molten steel is vigorous, CO in the slag increases and H₂O decreases.
The hydrogen content in molten steel is proportional to the partial pressure of H₂+H₂Ocontained in gas in the slag and is inversely proportional to the FeO content in molten steel. Consequently. hydrogen increases as a result of the declination of boiling activity due to the decrease of oxygen content in molten steel. Especially, by killing the molten steel for a long duration, the hydrogen content increases considerably.

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Die Verfasser sind in der Lage, Flocken in festem Stahl herzustellen, indem Wasserstoff von hoher Temperatur durch das Material geschickt wird. Dasselbe Verfahren kann auch bei geschmolzenem Stahl Anwendung finden.
Nach ihren Erfahrungen ergeben sich folgende Resultate
(1) Flocken im Stahl werden entstehen, ween ein gewisser Betrag an Wasserstoff im Stahl vorhanden ist.
(2) Für die Bildung der Flocken im Stahl ist nicht nur der Wasserstoff, sondern auch die thermische oder umwandelnde Spannungen von groszem Einflusz.
(3) Die verschiedene Stahl-Material-Zusammensetzung ist ebenfalls ein wichtiger Faktor fur die Bildung der Flocken.

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It is ascertained with hundreds of large steel ingots that the briskness of making sparks from specimens taken from molten steel by dipping iron wire at the ingot head, or microscopic dirtiners of specimens thus taken, may be an exact guidance for the judgement of the properties of the ingot.
In the same occasion of dipping iron wire, we may often find floating solidified steel which after having grasped slags, goes soon into the lower portion of the ingot and causes the origin of harmful type of inclusions.
In this paper are described such method for the judgement of steel ingots and its practical applications for the improvement of the manufacturing Process of steel.

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As reported previously, the authors could give the same hardness as Widia to the 18% Co super-high-speed steel, by a particular heat-treatment and, at the same time, they found a fact that by applying this heat-treatment they did not necessitate the use of widia to drill the hard special steel plate, and the cutting work was carried out fast and easily, even with ordinary machines of old type. This particular heat-treatment is composed of quenching and the repetition of such tempering as to heat for short time and to cool, and by this tempering method the hardness of that tool steel became higher than that by the ordinary continuous tempering process. In the present paper, the authors dealt with the physico-metallurgical research refering to the machanism between this heat-treatment and thereafter hardness increment, and also the investigation of elements which are necessary for such increase of hardness. From the results of their studies, the authors reached to the following conclusions: The chief cause of this increase of hardness is the fine and uniform precipitation of carbides with the transformation A→M which occurs at relatively low temperature in the course of cooling, by this heat-treatment. And this transformation is not the socalled Ar, " but the transformation A→M which follows to the precipitation: The essential elements which are absolutely necessary for such hardness increment, are W, Cr, V and Co, and Mo is the secondary element which merely promote this increase of hardness.
These researches were carried out during the period from 1933 till 1934 and published on the Spring meeting, 1936, in Tokyo.

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Nickel-thoria catalyst, used for the determination of oxygen in iron and steel by the hydrogen reduction process, is generally kept in containers of horizontal type. In this kind of container, hydrogen is liable to be not in uniform contact with nickel oxide, from which metallic nickel is produced as catalyst by reduction. Consequently, it is difficuit to obtain a satisfactory blank value of the catalyst The authors replaced the container of horizontal type by a vertical type in order to let hydrogen reduce nickel oxide as completely as possible by bringing them in uniform contact, and achieved to keep the blank value of the catalyst very low, such as 0.037mg. per hr. when the catalyst is at about 250°C. The blank value of the reduction tube with a boat was 0·065mg. per hr. when the tube was heated at 1, 200°C. With the improved apparatus, experiments were carried out to investigate whether the sample in the form of fine powder can be adopted for accurate analysis or not. Armco iron, a commercial carbon steel and two special steels were used as the materials for the test. It was confirmed that the oxygen contained in Armco iron can be analized with satisfactory accuracy under the following conditions:-
(1) The thickness of individual grain of the sample should be less than about 0·1mm.; (2) The surface oxygen of the sample should be extracted by reduction in hydrogen at 500°C during more than 1·5hrs. before the analysis is begun; (3) at the reduction temperature of 1, 200°C, time to be kept at this temperature should be at least 2hrs.
The accurate analysis of other kin ls of steel was unsuccessful under the same conditions as stated above. It was found that a very careful investigation should be carried out befor a satisfactory result is obtained about these materials.

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Using so-called "low temperature reduced iron" which was industrially manufactured by a special rotary kiln from rich iron ores produced in Manchuria and China, mild steel was obtained by the electric steel-making process. The author investigated that the mild steel so produced has a considerably high toughness and a superior weldability (for both the ordinary and fogged welding ), in comparison with ordinary mild steel, as the results of the experiments made on the mechanical properties and weldability. Thus he explains the new special features of the steel made on the basis of sponge iron and gives a consideration on the superiority of such steel.

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