This experiment was performed to invesitigate the rheological properties of rock under the high confining pressure.
The new apparatus made up three parts which was designed owing to develop the Bridgman's high pressure technique.
One of them, the pressure vessele could be withstood to 4, 000kg/cm² of hydrostatic pressure. The other parts made up hydraulic press and its pressure generator. The total normal compression of press was 130ton on the hydraulic ram which contacted the specimen. The experiment carried out on each relations between stress strain, strength and confining pressure. The sample was selected from lime-stone. The effect of confining pressure was distinguished on the strength of lime-stone. The strength of lime-stone under the confined pressure up to 3, 000kg/cm² was 4 times as large as it under the atmospheric condition. Moreover lime-stones showed the plastic deformation under the high pressure up to 1, 000kg/cm² at stress-strain diagrams.

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Recently, in order to clarify earth pressure phenomena, the stress in rock has been frequently measured by stress relief technique. The measured stress, however, is the-disturbed stress by the opening in which the measuring apparatus is placed. As it is supposed that the knowledge of the original stress, the stress that, would exist if the opening were not made, will be helpful to the investigation of earth pressure phenomena, the authors have studied theoretically the method to find the original stress. It is found that the measurements of principal stress at more than three points on the wall surface of a drift or the measurements of deformation of a bore hole in more than six directions enable to determine the original state of stress The detailed method of calculation with an example of its application are suggested in this paper.

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Since most arsenical ores contain both arsenopyrite and pyrite, the mutual reaction between FeAsS and FeS₂ has been investigated with the use of thermogravimetric method and differential thermal analysis in both vacuum and nitrogen atmosphere.
The reaction temperature was measured by quarz spring balance in both vacuum and nitrogen atmosphere, and weight decrease was found to begin at about 550°C in N₂ and 500°C in vacuo respectively. Further experiments using thermal differential analysis gave the reaction temperature of 560°C in N₂ atmosphere.
The resulted residue was detormined to be pyrrhotite (FeS) by X-ray and chemical analysis, and the sublimate product was As₂S₂ with excess As. This arsenic disulfide gave a distinct X-ray-diffraction pattern which was not listed in the A. S. T. M. data file and Hanawalt table.
The reaction velocity was also measured at the temperature range 550°C, -650°C using the mixture of mole ratio FeAsS/FeS₂=1.0. It was found that the reaction velocity shciwed good agreement with Jander-equation, from which the activation energy of 94.8kcal in N₂ atmosphere and 83.2kcal in vacuum was derived.

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Purification of magnetite containing mainly sulfides as impurities was achieved by a combination of physical method, such as flotation, magnetic separation, etc., and chemical treatment with nitric acid. Nitric acid was used because (1) it easily dissolves both sulfides and a part of non-ferrous metallic oxides, (2) it did not dissolve comparatively iron oxides, and (3) it could easily be recovered.
Results of experiment were as follows:
(1) Sulfides in magnetite were almost completely leached by treating the are with 60% nitric acid at 50°C, and with 20-40% nitric acid at 70°C for 3 hours.
(2) The higher the sulfides content of the iron oxide, the more amount of the iron oxide are were dissolved by nitric acid treatment. This might be attributed to sulfuric acid formed by the oxidation of sulfides with nitric acid.
(3) The rate determining step of desulfurization of sulfides was surface chemical reaction of the first order when isolated sulfides particles predominated. After isolated particles were diss olved out, the rate determining step changed into something like apparent diffusion of nitric acid into solid phase or, more exactly, intrusion of nitric acid into the surface of sulfides particles.
(4) The nitric acid and sulfuric acid in the waste solution could be separated by precipitating the basic sulfate Fe₂0₃-2S0₃-H₂0 when the above solution was heated.
(5) The iron sheet was prepared by melting the sponge iron, which was obtained by reducing the above purified are in hydrogen stream, was examined by auto-recording fluxmeter and showed the value of 10, 000-13, 000 as μmax and 0.5-0.3 as Hc.

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