In the present second report, pyrite cinder samples from Buzyun (Manchoukuo) and Syôwa Steel Works (Japan) were examined to determine the microscopic structures. Experiments were conducted concerning the reduction of the ore in hydrogen, the difference between MnS and FeS by making sulphur prints, magnetic intensity of some parts of cinders and magnetic separation, etc. It was found that the copper is contained as CuSO₄, covelline, chalcopyrite and bornite; the iron as ferrous oxide, hematite and magnetite; and the sulphur as FeS and pyrrhotite. From these results, it was presumed that there are four layers in pyrite cinders.

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"Seiko-gentetu" is a new nomination by Nippon-Tekkokyokai (Iron and Steel Institute of Japan) for the raw iron as substitute for scrap iron. They have subdivided it into 4 qualities: "sentetu" (pig iron); "juntetu" (pure iron) and "sokô" (raw steel); "kaimentetu" (sponge iron); "ryutetu" (Luppe) and "bôtetu" (bar iron). Beside the products from blast furnaces, there are other pigs from rotary kilns and from electric furnaces. Pure iron is produced mainly by electrolysis. It is interesting that the raw steel is a high-purity steel made directly from the local iron ores and sand iron with the electric furnace by utilizing the low-cost electricity. Sponge iron is made with rotary kilns, "tunnel" furnaces and gas-fired furnaces, while Luppe (loop) is made exclusively with the rotary furnace. Bar iron today is made mainly by a high-frequency electric rabbling method.
There are so many kinds of the raw iron for steel manufacture, but the problem of a scrap iron substitute has not been settled. In point of the amount of production, methods of production and utilization, civilians and officers should unite in solving the problem through all difficulties. Luppe and sponge iron are suitable for the mass production, and so may be regarded as the fundamental raw irons in steel manufacture. As for the special raw irons containing nickel, chromium, vanadium, cobalt, etc., cooperation in research is still necessary.

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Heretofore it has been discussed chiefly on the ground of experience, what degree of the surface hardness of the backing-up roll for the four-high mill would be suitable. Hence, some one suffices himself at the softer surface with about 45 of Shore hardness, another prefers the harder roll with about 80-85 of Shore hardness, leaving the user in distress for selecting the suitable hardness. The author studied this problem in the line of elastic-dynamies, investigated the distribution of stress in the material proximate to the roll surface, explained the phenomenon of surface spalling by fatiguebreakage of the roll material, and gave the theoretical reason for seleeting the optimum surface hardness. Besides, the author made a calculation on the cold strip mills in operation at the Yawata Iron Works and correlated the calculated value with the theoretical.

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(1) Relation between the Welding Condition and the Change of Properties of High Carbon Steels.
Not only the hardened zone is detected in the welded part of high carbon steels, but sometimes also the welding crack appears in them. In this research the author has studied to find the welding conditions to mitigate hardening or to prevent weld crack.
Three kinds of high carbon steel with 0·4%, 0·55% and 0·76% C respectively, have been subjected to various tests.
The weld hardening and the crack generation are mainly affected by the carbon content and the cooling velocity. The more the carbon content in steel, the more the number of crack or the length of crack on bead. The cooling velocity, in welding practice, has two important factors i.e., the electric current and the welding speed.
The author has found two kinds of crack or fissures on bead. The former is generated by theshrinkage stress, the transformation stress etc. and the latter is mainly caused by the transformation stress such as due to the local formation of martensite at comparative low temperatures. From the result of various tests it is concluded that we should apply such welding conditions as slow speed and low current as possible for preventing crack generation.
(2) On the Building Up of Worn Tyres.
As an example of practical application of the abovementioned tests, building up of worn tyres was executed in the experimental condition and this welding repair practice showed superior results on both sides of theoretical tests and practical uses.

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Man sagt, dass die Austenitskorngrösse das eigentliche Merkmal des Stahles ist. Um die Austenitskorngrösse zu suchen, pflegt man den Stahl bis 925°C zu erhitzen, und es 6 Stunden lang bei dieser Temperatur zu erhalten; und nur jene Korngrösse unter diesem fast zufälligen Zustand ist allein leicht als eigentlich angesehen. Aber die Korngrösse verändert sich mit der Erhitzungstemperatur und auch mit dem Erhitzungsdauer. Der Verfasser sucht diesem Veränderungscharakter der Korngrösse durch eine speziale, die Korngrenze entwickelnde Methode, d.h., die Doppelhärtungsme thode, und erkennt, dass es einen grundsätzlichen Unterschied zwischen dem Kohlenstoffstahl und dem Sonderstahl gibt.
Schon hat man die Tatsache klar gemacht, dass die Austenitskorngrösse vielen oder wenigen Einfluss auf mehreren Eigenschaften des Sthales ausübt. Ihre starke Wirkung äussert sich beim Kohlenstoffstahl, weil dieser, wegen seines Mangels an einflussreichen Elementen, empfindlich gegen den andern Faktoren ist; während beim Sonderstahl ihre Wirkung gegen der Legierungsgrösse kleiner wird. Das Element, das den Einfluss der Korngrösse höchst unklar macht, ist ohne Zweifel der Nickel.Neuerdings muss man um die nickellosen oder nickelarmen Sonderstählen anstatt der nickelhaltigen oder nickelreichen handeln, so kann man den Einfluss der Korngrösse auch beim Sonderstahl nicht auslassen, besonders beim Automobilstahl, bei welchem es um die Gleichmässigkeit sich handelt.
Zum Schluss kommt der Verfasser aus eine Methode zur Beherrechung der Austenitskorngrösse des Stahles und gibt einigen Auffassungen darüber.

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The determination of oxygen in steel is highly important for the study of steel making reactions, and the most appropriate, means of determination is the vacuum-fus on method.
Among several types of vacuum-fusion furnaces the authors adopted a carbon-spiral-furnace which was not so expensive, and examined the accuracy of our apparatus. The results was satisfactory as follows:
The graphite crucible is heated and degassed at 2000-2100°C for 2·5-3 hours till the pressure in the furnace becomes the order of 10^-4mm Hg. When the temperature is lowered to the experimental temperature of 1600-1700°C, the pressure in the furnace reaches the order of 10^-5mm Hg, and shows the blank value of 0·10-0·05cc CO/15mn at room temperature By the use of the present earbon-spiral furnace, the 98% oxygen inclusion of the pure Fe₂O₃ powder and the 97% of the pure SiO₂ powder may be extracted.

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