In smelting the titaniferous iron ore in modern blast furnace, the non-metallic compounds of titanium being formed easily has been discussed in my previous papers with the results of various experiments. The reactions are based chiefly on the formation of the infusible compounds of titanium, owing to the effects of nitrogen in blast in high tempereture working. Titanium as reduced exists in slag and pig iron ingeneral in the forms of carbide (TiC) nitride (TiN) and cyanonitride (Ti₃CN₄?)
In this paper the author quotes the leading conclusions, which have previously been proposed about the compounds of titanium and gives a brief discussion.
To investigate the formation mechanisum of non-metallic compounds of titanium from titanic oxide in the furnace atomosphere the author has endeavoured to make the more pure one of several kinds of the compounds of titanium, and studied the effect of iron for those samples. They have been melted in a high vucuam electric furnace with iron, the products being examined both microscopically and analytically.
The author discusses also graphycally the mode of change of titanic oxide into the non-metallic compounds of titanium the blast furnace, and gives his idia to smelt the titaniferous iron ore.

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The influence of several elements on the quench-hardening of steel was studied and in this paper the effects of Ni, Cr and Co were described. The specimens were made by adding about 0.5, 1.0, 1.5 and 2.0% of these elements into the molten carbon steel with eutectoid composition and finished into a cylinder of 30mm in diameter and 30mm in high. The specimens were quenched from 750°, 800°, 850°, 900° and 950° into water and oil. The hardness was measured in 1mm distance along a diameter on a section which was ground off 5mm from the surface, using the Vickers' hardness tester. The transformation points of these steels were determined by means of a differential dilatometer. The microstructure was also examined. From the hardness distribution on the sectional surface the following conclusions were deduced: -Nickel increases the quench-hardening effect of steel; Chromium increases the effect very markedly; Cobalt rather decreases the effect.

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The most important properties of moulding sands in reference to the refractoriness are the so=called "durability" and "burning on". In this report, the experiments by casting for the moulding sands of Japan and Manchuria were conducted in the same conditions as in foundry as far as possible, and after it, the used sands and the surfaces of casting were investigated from the points of view of the durability and the burning-on.
Comparing the results with the properties of bonding materials of moulding sands related in the 3rd report, the following conclusions were obtained.
(1) One of the most important properties of moulding sands influencing the durability is the quality and the quantity of bonding materials, e.g. the durability of moulding sands depends chiefly upon the reversibility of the water of kaolin and the irreversibility of the water of ferric hydrogel after heatihg at 400°C. Therefore, the durability of moulding sands which depends mostky upon the latter for its bonding power is comparatively weak.
(2) The durability of moulding sands depending mostly upon the quality and quantity of bonding material, the water-vaporization-experiments by the thermo-balance by prof. K. Honda are the most suitable methods for the durability test of moulding sands.
(3) For the burning-on, the most influential factor of moulding sands is the mineral composition of sand grades: The feldspar group of lower melting point is undesirable, especially orthoclase is detrimental. The naturally bonded moulding sands of Japan and Manchuria contain comparatively large quantity of the feldspar group.
(4) In order to protect from the burning-on, it is necessary conditions for bonding part that after casting, the bond near at the caked metal fuses in glasssy state, incloses sand grains and thus makes the so-called "scale". In cooling, it parts easily from the surface of casting by the difference of coefficient of expansion.
(5) The same principle holds good in steel casting. If necessary to lower the melting point of the bonding material with the purpose of making the scale, the addition of powdered iron oxide to it is one of the effective methods to protect from the burning-on.

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In the first part of the research of heat-resisting Al-alloys, which was carried on to investigatg the Y-anoy series, the author could not find any excellent alloy comparihg with the socalled Y-alloy which is wellknown in England. Hence, he undertook the systematic studies of heatresisting Al-alloys. The specimens were all chillcast and the experiments were made at the temperatures from the room temperature to 500°C, on pure aluminium, binary, ternary, quaternary alloys and so on, addiug the following elements, Cu, Zn, Ni, Cr, Mn, Fe, Si and Mg, and the results were discussed. On the othe hand, the alloys containing Cu 4%, Si 1%, Mg 1% and Cu 4%, Si 10%, Mg 1% showed the excellent mechanical properties after heat-treatment. Therefore, he investigated the effects of Ni, Cr, Mn and Fe upon the improvement of mechanical properties of these alloys. Moreover, extraordinary implovement was obtained by adding Ti as TiCl₄ into thbse alloys: for example, a certain specimen showed a very high tensile strength, 46kg/mmmm² at ordinary temperature and 30kg/mmmm² at 300°C. The reasons for gaining such high tensile cast Al-alloys were explained in detail on his theoretieal consideration.

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