The ore deposits of Tsuchihata mine consist mainly of so-called “stockwork deposits” which are considered to be intermediate forms between vein and black-ore deposits. Three main ore-bodies now being mined -Hatabira, Shirasuchi and Uenono-are of chimney type consisting of numerous closely spaced veinlets or stringers which contain chalcopyrite and pyrite with some chalcocite, covellite, azurite, chalcanthite, etc., as ore minerals in disseminated forms.
Undercut caving method, a sort of block caving, has been adopted since 1925 in Hatabira, and later in other two ore-bodies. Much improvements have been done with respect to working conditions and operation economy, until the drift-caving method has been standardized. But in some places the “dilution” of ore, mainly due to cap rocks and filled sands in subsidence, rose to such-extent that it compelled to abandon the ore after extracting onyl 70 percent of the estimated reserves.
To prevent this dilution the application of new mining methods, i. e. top-slicing or square-set, have been undertaken, the results of which are to be reported in another occasion.
In addition it should be mentioned that the cement copper is being recovered in considerable quantity from the mine water by scrapiron precipitation at the mine.

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The quantity of methane, argon and helium that can be put into coal or rocks in some coal measures as free gas or adsorbed gas has been investigated under various pressures. The rocks adsorb but a little quantity of methane or argon, while the coal adsorbs far greater quantities of them and a small quantity of helium. The quantity of methane adsorbed in coal increases with pressure, the rate of increase, however, decreasing with pressure. The authors have also investigated how and to what extent the sample should be crushed in determinining the quantities of gases put into it, as well as how to determine the porosity of samples.

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The effect of phosphorous ion on the dispersion of ferric oxide suspension has been studied by the measurements of the amounts of adsorption ζ-potential and so on.
The experimental results are as follows:
ζ-potential of ferric oxide increases not only with the concentration of hydroxyl ion, but also with that of phosphorous ion in the solution.ζ-potential is, however, higher in the presence of phosphorous ion than in the absence at the same pH value. It is considered that this difference is due to the adsorption of phosphorous ion on the surface of ferric oxide. The suspension always disperses where ζ-potential is high.
The effect of phosphorous ion on the dispersion of ferric oxide suspension should be attributed to the increase of electrostatic repulsion resulted from the adsorption of phosphorous ion and hydroxyl ion formed by hydrolysis of phosphate on the surface of ferric oxide.

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Though it is clear from the preceding report that the floating mineral must satisfy both the supporting force equation (i), and the Young equation (ii), these two do not join mathematically with each other in these states. In this report, the supporting force equation (iii) is substituted for the equation (i), where T_l is the air-water interfacial tension or energy, θ is the contact angle and a is the inclination angle of the mineral plane to the horizontal.
f (per unit length) =T_l sin (θ-α)(iii)
This f has the positive and the negative sign. +f is the force acting toward the mineral to float and-f is the force acting toward the mineral to sink.
On the other hand, instead of the Young equation, the surface free energy change W (the work done by the system per unit area) when the mneal moves at the air-water interface, is given by the following equation. This energy change W is considered a measure of wettability,

W=T_l (cos θ-cos α)(viii)
expressing all types of wetting of the floating mineral, and when W > 0, the wetting proceeds spontaneously
(T_s →T_ls) which means “wettable”, or “hydrophilic” and when W<0, the wetting recedes spontaneously (T_ls→T_s) which means “nonwettable” or “hydrophobic”, and when W=0, the wetting stops.
Combining these two equations (the dynamic and the thermodynamic condition), the following relations are obtained. These relations explain the fundamental principle of flotation that the wettable
W=0...f<0 W=0...f>0 W=0...f=0
mineral sinks and the nonwettable floats.
When the contact angle is 0°<θ<180°, the mineral at the air-water interface has always both the hydrophilic (W > 0) and the hydrophobic surface area (W < 0), and neglecting the gravitational effect, the mineral are moved spontaneously by either the hydrophilic force (-f) on the hydrophobic force (+f) to the area of W=0. This is the reason why the mineral clings to the air-water interface by the hydrophilic and the hydrophobic force, and one can easily understand that the force supporting the mineral at the upper interface of bubble is the hydrophilic force. And the hydrophilic force plays important roles not only in making the mineral to sink into water, but in supporting it at the interface, and cooperates with the hydro phobic force to make up the characteristic of flotation.

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A semi-pilot plant by T. B. P.solvent extraction process was constructed to study several process variables in controllng impurity content and particle sizes of ThO₂ for nuclear use.
The results obtained are as follows:
(1) Mnch care should be taken to adjust the concentration of thorium as well as the acidity in feed solution. High thorium and nitric acid concentration gave best results.
Scrubbing stage was also important. Use of high nitric, acid solution in a small ratio was necessary to obtain high purity ThO₂.
(2) A typical analysis of the purified ThO₂ was as follows: Gd, Sm, Eu, Dy, Nd, Pr, La and Ce, were less than 0.25 ppm respectively, B was less than 0.25 ppm, Fe, Cu, Mg and Mn were less than 2.5 ppm respectively.
(3) Particle sizes of the products could be controlled to give <1 micron to several microns by selecting the conditions to prepare the preceding thorium oxalate precipitates.
(4) The reactor grade ThO₂ plant could run economically on its semi-pilot plant basis (several hundred kgs of ThO₂ per month).

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ニッケル鍍の組成と平衡成分との関係について検討するため, 人工的に合成したNi-S系, Ni-Fe-S系の試料およびニッケル製錬の転炉から採取した試料について粉末法によるX線分析を行ない, 次の結果を得た。
れらの結果からγ+ε+π相の安定領域で平衡するNi-Fe合金相の組成はNi約50～60atom.%のものど推定された。
本系の三元化合物 (Ni, Fe) ₉S₈(Pentlandite)(立方晶系) の存在範囲および格子常数を測定した。その存在範囲はNi 30.7atorn.%, Fe 22.2atom.%, S 47.06atom.%からNi 22.2atom.%, Fe 30.7atom.%, S 47.06atom.%にわたり, またその格子常数はFeS飽和のものについてはa=10.129kX, Ni₃S₂飽和のものについてはa=10.095kXであつた。
また硫黄50atom.%断面の試料にあらわれるNis-FeS₁+x全率固溶体η相 (六方晶系) の格子常数a, cおよび軸比c/aを測定した。η相のこれらの値は試料のNi品位の増加とともに, 直線的に減少することが明らかとなつた。
(3) 転炉から採取したニッケル鉄について相の確認を行なつた結果はNi-Fe-S系の試料の結果とよく一致した。

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