From the amount of silicon reduced into steel in the process of making it in an acid furnace, it can be ascertained whether the ferrous oxide content in the molten steel is large or small. In other words, the reduction of silicon in the steel making, indicates whether the steel is spontaneously deoxidized or not. Furthermore, in making steel in an acid open hearth furnace, if the amount of the reduced silicon in the molton steel is excessively large, the ferrous oxide content in the molten steel is likely very little. In such a case, the molten steel readily absorbs hydrogen from the furnace gas in no small amount, thereby causing flakes in the steel product. It is clear, therefore, that the reduetion of silicon in the steel making has an important bearing upon the quality of the steel made.
The writer has made some investigations about the influences of the melting temperature of steel and of the chemical composition of slag upon the reduction of silicon by making use of an acid high-frequency furnace, and the principal results obtained may be summarized as follows:-
1. When the melting temperature is low, the carbon in the molten steel is oxidized chiefly by the oxygen in air. As the temperature rises, however, the portion of carbon consumed for the reduction of silicon increases.
2. The speed at which silicon is reduced, increases as the rise of melting temperature.
3. No influence of slag composition upon the reduction of silicon is noticeable. This fact may be attributed to the small ammount of slag used as compared with that of steel melted.
4. The influence of the number of the uses of lining upon the reduction of silicon was manifestly evident; as the number increased, the reducing speed of silicon. decreased. somewhat rapidly at the begining, and then slowly until finally it reached an asymptotic value.
5. Test plates cut from the ingots produced and also from the billets forged therefrom and air cooled, were fractured. No flakes could be found in any of the test plates even when it contained reduced silicon as much as 1·10 per cent. We may, therefore, safely say that the fact that more flakes appear in acid open hearth steel which contains a large amount of reduced silicon, is not because the silicon itself is injurious, but because the furnace condition which makes so much silicon to be reduced, is harmful.

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Because of the length of rails which was renewed from 10m to 20 or 25m in the Japanese Government Railways, the blooming and rail mills at the Yawata Steel Works had to be rebuilt (as shown in Fig. 1) in order to make such long rails.
As to the rolling methods of rails, the following three methods are usually adopted; i.e., the diagonal method, the cutting-in and flange-bending method and the slab-and-edging method,
Of these methods, we approbated the slab-and-edging method in view of little wear of rolls and smooth working of mills.
The rails are speedily treated by the roller straightening machine, after which they contract 1·05mm/min length owing to the variation of the cross-sectional area.

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In the first report (The Journal, of this Society, vol. 24. 1938 p. 24) the permeability of moulding sand is dealt with, whilst in this report the bonding strength of moulding sand is theoretically studied, the following conditions being taken as the important factors affecting the bonding strenght of moulding sand.
1. Sand grains,
a) size of sand grain, b) form of sand grain.
2. Bonding substances,
a) clay content, b) moisture content.

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The author investigated the relation between the cooling velocity and the amount of the retained austenite in the Ni:Cr:Mo steel, and also the effect of the retained austenite on the impact value.
The results of the investigation are outlined bellow:-
The content of the retained austenite with quenching increases as the cooling velocity inaeascs up to about 300°C/sec, and it decreases when the velocity exceeds this limit.
When the tempering temperature is lower than 150°C, the specimen quenched in oil so as to retain the austenite shows a higher impact value than that which contains no austemite. In the case of the tempering at 200°C, however, the former showe a lower impact_yalue than the latter.

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The mechanical tests were made on the approriate properties required for the material for propeller hubs relating to the following five kinds of steel, viz.,
chrome-molybdenum steel (C 0·3%, Cr 1·2%, Mo 0·5%),
chrome-vanadium steel (C 0·3%, Cr 1·0%, V 0·1%),
nickel-chromium steel (C 0·3%, Ni 4·5% Cr 0·5%),
nickel-chrome-molybdenum steel (C 0·3%, Ni 3·0%, Cr 1·2%, Mo 0·4%), and
nickel-chrome-molybdenum steel (C 0·45%, Ni 17%, Cr 0·8%, Mo 0·2%).
The tests were particularly made on the last named steel which appears not so widely used as the other kinds of material for the purpose.
The results show that this steel is of the excllent quality as a material for the manufacture of the hubs in view of its strength and economy.

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