The Takatori district is geologically composed of Paleozoic sandstone, clayslate and quartzite, which generally strike NE and dip monoclinally to NW. The ore deposit belongs to the hypothermal quartz vein, accompanied by wolframite, cassiterite, arsenopyrite, pyrrhotite, pyrite, chalcopyrite, sphalerite, galena, stannite, bismuthinite, lithia mica, monazite, fluorite, topaz, rhodochrosite, : calcite, sericite, chlorite and others. The veins are classified into two groups from the attitude, i. e., (a) the veins which strike NW, dipping steeply to NE or SW, (b) the horizontal or flat veins which link the steeply dipping veins of group (a). The original fissures of the both types of veinsare tension cracks. So, it may be interpreted that these fissures correspond to the plane of the maximum normal stress resulted from the NW-SE compressive force, which caused the folding of the Paleozoic formation with the axis of NE-SW. Judging from the locally disturved structure of the Paleozoic formation, a mass of cryptobatholith is inferred to occur beneath the area of the are deposit. The country rocks suffered sericitization and silicification, partly impregnated by tourmaline, fluorite and topaz.
Similar features of the vein system have been reported in some tin-tungsten vein deposits such as in the Kuga tin-tungsten mine, the Akenobe tin-tungsten-copper-zinc-lead mine, the tin-tungsten mines in the eastern Andes of Bolivia and others.

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In Kamioka Mine of Mitsui Mining and Smelting Co., several efforts have been made to get the maximum extraction percentage safely in pillar working.
As one of attempts for this purpose, the stress in pillars has been measured by means of the photo-elastic apparatus which was contrived at those days. It has been noticed from this measurement that the stress in pillars varies closely as the progress of mining, and that also the direction of the maximum principal stress which is easily detected by the apparatus gives a useful indication about the state of rock pressure. After five years' investigation, the photo-elastic stress measurement is proved to be one of the powerful methods for the rock pressure control in an elastic ground.

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Wire breaking occurred in the main rope of the aerial rope way, and some tests on wire breaking were tried, and results obtained are as follows.
1. Wire breaking appeared more quickly when hardness of one pulley was more higher than the others.
2. Wire breaking was retarded when sagging of main rope was small.
3. There were 2 sort of wire breaking viz., crack occurred first only in the upper side of wire and then breaking happened, and crack occurred both in the upper and lower sides of wire.
4. When material of pulley was made of soft metal, cracks occuring in the main rope wire were very few, so, breaking of wire was delayed and then increasing speed in the breakings of wire in a main rope was retarded.
5. Scanty strain was generated in the wire when soft roller was used, and when the hardness of roller was higher than that of the former larger strain was generated.
These results were obtained with pilot apparatus of aerial rope way 1st, 2nd and 4th nucha. 5th cervix was, obtained by wire testing machine which was designed by our college, and the 3rd cervix was obtained through these two testings.

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According to the continuous curve of gas desorption of coal a percentage of gas volume emitted at initial to the total (D_init) and a ratio of gas volume emitted at initial to the one occluded inthe coal (R_init) were calibrated. Besides, , the authors found a hysteresis of gas in the repeating process of adsorption and desorption, and estimated a gas accumulability of coal (M_ac); and moreovermeasured “Δp” which indicates a gas volume emitted at initial in a calibrating method standardized by I. L. Ettinger.
Thus, four properties in gas desorption of coal were closely examined. As a result of study on the mutual relation between four properties in gas desorption of the coal and some qualities of the one, the authors recognized the followings that
1) any coal which has higher values of D_init, R_init and M_ac is more pulverizable in general, . therefore, so as to estimate the situation of danger zone of gas issue a tentative method of pulveri zability of coal might be more effective,
2) in contrast to four properties in gas desorption with one another, gas zones in which packed the small crushed coal could be classified into six groups, and two of them might be marked in danger of gas issue.

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Electro-osmotic velocity, adsorption density, and floatability were measured on quartz, fluorite and scheelite in the collector solution, and the relation among the adsorption density of collector ion, the change of zeta-potential and the floatability of mineral particles were discussed.
The results are as follows:
(1) The zeta-potential at each mineral-collector solution interface varies remarkably at each proper solution concentration range. On the other hand, the floatability of each mineral also increases notably at the solution concentration of the approximately same range. Accordingly, the floatability is correlative with the difference of zeta-potential in each system.
(2) The adsorption of each collector ion on each mineral increases with the solution concentration and it shows Freundlich's isotherm. It is, further more, found that the difference of zetapotential increases with the adsorption density at the proper low solution concentration range in each system.
(3) On the relation between the adsorption and the zeta-potential, the equation as follows was derived from Stern's theory, n*=(√Dn/2πkT-D/4πδei) ψ₁+D/4πδeiψ₀
From above results, it may be said that the difference of zeta-potential is correlative with the adsorption density closely at the proper low solution concentration range and therefore the floatability of mineral particles correlates with the difference of zeta-potential.

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One of major functions of this type of flotator is considered to be recomminution of the bubbles flown in, the mechanism of which has not yet been known in detail.
Starting from this point and by way of comparative study of the behaviors of natural air bubbles around the columns placed in the water-flow-channel, the author has confirmed the following results.
1) Vortices induced by the separation of the boundary layer of the cylinder wall, elongation due to the contraction of flow tube between the columns, strained lateral elongation due to their collision against the high pressure zone formed at the front side of the column tobe most effective comminutive actions against the bubbles.
2) Mingling of the frother, viscous liquid, solid particles inflicted essential influences upon the above actions.
3) To design the impeller and the baffling blade employing a series of round columns so as they can effectively utilize the above actions is necessary.
The result shown above is similar to the air bubbles in the water-flow around a flat-plate and it is the basis by which the mechanism of recomminution of air bubbles in the impeller of this type can be made clear.

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As the fluid-solid systems possess property similar to that of: viscosity in liquid, which will markedly influence their flow characteristics, the viscosity concept may be readily appiled to the prediction of the condition under which the roasting of ores will be difficult. Accordingly, a study has been made of the viscosity of the fluosolid roasting systems with zinc ore mixed with some copper and lead ores as impurities.
From the results, it was found that the tendency of fluidized bed to lose stability increases as its viscosity increases, and the impurity limit which affects upon stability of the bed was obtained.

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In previous reports, we have been studied the effects of current densities and the compositions of electrolytes on the corrosion of pure and silver-containing lead anodes in electrolytic zinc deposition. From these results, it was found that the corrosion of lead anode was considerably decreased by the addition of silver up to about 0.51%, above this the corrosion of anode became practically negligible. In present studies, therefore, testing anodes of pure lead and 0.20, 0.51, 1.03, and 2.49% silver-containing lead were used. The results were as follows:
1) The anode potential is decreased with the rise of temperature from 20 to 50°C, with the rate of 3.2mV/°C.
2) The amount of anode slime is not materially affected by varying the temperature.
3) Distribution of lead in cathode zinc at each temperature is almost uniform when the silver content of lead anode exceeds 0.51%, but below this silver content the maximum lead content is found in upper part of cathode at lower temperature and in lower part at higher temperature.
4) When the silver content of lead anode is below 0.51%, the mean lead content of zinc deposit shows minimum at temperature 35°C, above this silver content the lead content of cathode slightly increased with rise in temperature.

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