Since the war we have operated the blast furnace by charging only domestic iron ores and produced pig iron with the average content of sulphur running up to 0·17% in 1946. Before charging the domestic ores the average content of sulphur in the charged raw material was about 12 to 14kg. per ton of pig iron tapped, but recently it has increased up to 25 to 30kg. Generally 70 to 75% of the sulphur runs out with the slag and 20 to 25% of it with the gas. The average content of sulphur in the coaking coal was 0·7% and practically none of the sulphur decreased by washing nor coking. The content of sulphur were generally large in the fine and sintered ore under 10 mm sizes.
Generally the ratio of desulphurization by sintering is from 80 to 90% and it is possible to make it over 90% by improving the method of crushing and screening.
To desulphurize by briquetting it is necessary to roast it up to 1200°C. By using the cement rotary kiln we found out that it is possible to desulphur the lump ore from 70 to 80%. Desulphurization within the blast furnace is 94 to 95% which gives the same ratio and shows no difference whether it be foreign or domestic. Decrease in the blast pressure and the furnace tempeture give a bad effect on desulphurization. It is desireable to have a content of 1·0 to 1·5% of Mn in the pig iron and a basicity over 1·3 in the slag. After tapping about 25 to 35% are desulphurized in the ladle on the way to the pig casting machine and about 30 to 35% when the molten pig are traosfered to the open hearth plant by way of dead mixer. It is also possible to desulphurize 40 to 60% by adding 3 to 5kg. of soda ash per ton of pig iron, but at present soda ash are not available. About 15% of the sulphur are removed by slagging off in the dead mixer.
We have come to the conclusion that in order to reduce and refine domestic iron ores it is best to screen it into lump and fine ores and then give the desulphurizing treatment accordingly. This is not impossible but it requires tremendous effort and time.

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The suitable size and shape of refractory blocks which are used for furnace constructioh, are investigated from the following points.
(1) suitable size for handling by brick masonry.
(2) efficiency of shaping during production.
(3) accuracy of size of finished products.
(4) prevention of damage on manufacturing.
(5) relation between shape and thermal expansion tendency.
(6) espansion and dynamics of arch are studied on small models.

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The white cast irons which contain ca. 2·6% of C, ca. 1·15% of Si, various quantity of As and vqry minute quantity of other impurities were adopted as the specimens of the dilatometer.
The time required to complete the graphitization of the free cementite at constant temperature becomes somewhat longer as the As-content increases up to ca. 0·6%. The relation, however, is reversed when the As-content increascs over ca. 0·6%.

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The effects of carbon, chromium and tungsten on the properties of chromium-tungsten steel (0·50-0·60%C, 0·8-1·0% Si, 6·7-8·0% Cr, 6·7-8·0% W) used for valve steel of the engine were investigated. As the result of this investigations, it is ascertained that the effects are not so distinguished in the above mentioned range of composition of each element, above all chromium and tungsten. Therefore, it is considered that when this steel are used as a valve steel, each content of chromium and tungsten are able to be decreased to the lowest limits of the standard or rather below them.

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On the previous paper, the effect of compositions on the hot tear of steel castings were studied And in this paper, another factors affecting the hot tear have been studied.
The results obtained by these investigations are summarized as follows: -
1. The chief cause of the hot tear of steel castings is S, which remains in the grain boundary of primary crystals as FeS fluid film when steel castings solidify.
2. To prevent perfectly this hot tear, no compositional elenent is available, only Mn is most available for decreasing the hot tear. And for 0·01% S, 0·70% Mn or more is necessary.
3. No doubt, the thermal stress in the steel castings which occur during solidification is the cause of the hot tear.
4. To decrease this thermal stress, green sand mould is more effective than dry sand mould.
5. To prevent the hot tear chill and rib are very effective.
6. Most important idea is not to leave hot spot in the casting during solidif ication for preven. ting the hot tear.

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Linseed oil has been usually used for oil sand, while the author tried rather stale see oil in this study. The outline of experiment is as follows:
1. Sand used; Sea-sand (under 0·3m/m).
2. Emulsication; Alkaline soap (2%) is added for emulsicating agency at 70-80°C within violen stirring. The stale seed oil is more emulsified than the fresh seed oil.
3. Amount of oil; Oil 4% is adequate.
4. Time and Temperature of drying; 4hr. at 200°C, and 3hr. at 220°C are adequate.
5. The adequate amount of clay or bentonite added for the increase of tenacity of oil sand mus be below 3%.
6. Standard time and temperature of drying various size of cast iron were determined.

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