Oxidation rates have been estimated on various iron sulphide minerals such as pyrite, marcasite, melnikovite and pyrrhotite by observing oxygen quantity consumed by them.
At first, it has been ascertained that the rates are greatly infiuenced by water, temperature, and grain size of the specimen. Oxidation rates arerapid in order of pyrrhotite, melnikovite, marcasite and pyrite, and there existrather variation in them even among each mineral.
In order to compare with oxidation rates of various minerals, the factor (kθ₀) has been proposed by the writers. Here, (kθ₀) means the oxidation rate of apparent unit surface area of the specimen at θ0°C (cc/hr/m2)., (kθ₀) can be calculated from the equation, dx/dt=0.017 (kθ₀) e0.693 θ-θ₀/10, where xis the oxygen quantity consumed by the specimen (cc), t is time (hr), dx/dt is the oxygen consumption rate under the conditions of this experiment, and θ₀, θ₀ are temperature (°C) respectively.
Furthermore, consideration has been given to the oxygen poor air which often exists in the metal mine.

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Underground transportation is one of the most important factors for the operation of a mine which can be divided into two problems-transportation at working faces and main adits transportation.
High efficiency of transportation at working faces, the author concludes, can only be attained either by adopting a well suited method to the transports employed or its opposite.
Described below are the non-pillar overhand inclined long wall slicing method as an examplefor the former which uses scrapers as its main transports, and the short wall top slicing with Kappe method (accompanied with filling) as one for the latter which uses baby-conveyors as its main transports.
As regards main adits transportation, however, the descriptions are made with examples based upon the comparisons of:
(1) ordinary mine cars and dump cars.
(2) cages and skips, and
(3) belt conveyors and trolley cars.

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From the experiment at laboratory, this study has proved the following:
1. Relation between change of breaking load and that of elongation of wire rope caused by broken wires.
2. Influence upon the form of breaking load-elongation diagram by conditions of broken wires.
3. Influence upon the breaking load of wire rope by notch on wire.
4. Relation between decreasing of breaking load of wire rope and its diameter, and between.
decreasing of breaking load of wire rope and its galvanising. Further I brought foward, it is just proper, taking the maximal breaking load untill breaking of strand for the breaking load of a wire rope, in testing a wire rope which has broken wires.
The calculation of thebreaking load of wire rope has become convenient by showing: distribution coefficient of broken wires.
Method of inspecting the number of broken wires and method of rating the decreasing, percentage of breaking load of the rope, having broken wires, have been shown.

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By utilizing the periodic (trigonometric) function to the temperature of air current and being as a parameter the lapse of the time since the beginning of ventilation, this paper gives two mathematical solutions about the gallery temperature which is kept constant initially. The one is a temperature distribution in therock surrounding a gallery, the other is the cooling effect of the rock surface in a downwind direction. The later is an approximate calculation so that there are some errors to be annexed. But it is impossible to estimate its value for there is no complete solution moreover it is unable to observe above effect actually.
Generally speaking author emphasize that the solutions are very simple comparing the public one and are practical for mining engineers to estimate the various cooling effects of the gallery surface by ventilation.

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If the γ-rays radiated by radioisotopes are allowed to traverse any kind of material, they will cause mutual reaction such as photoelectric effect, Compton effect and pair production with this material and hence, pursuant to the following equation, they will be absorbed and will decrease and weaken in their intensity.
I=I₀e-μmpt
I: intensity of γ-rays passed through absorber I₀;intensity of incident γ-rays
μm: mass adsorption coefficient of a particular materia1
ρ: density of the material t: thickness of the material (absorber)
The writer planned to utilize the radioactive γ-rays radiatedby radioisotopes for undertaking continuous measurement of pulp density in flotation and also medium density in sink-float separation. Thus, various basic experiments were performed on numerous samples such as silica sand, ilmenite sand, copper bearing pyrite, galena and ferrosilicon by means of absorption method usingγ-rays radiated by Co⁶⁰.
The results of these experiments agreed completely with those obtained by the aforesaid theoretical calculation. Moreover, it was ascertained that by means of this method of determination, it would be quite possible to ascertain the density accurately to the extent of knowing the desired detection limits in actual operation, namely, the concentration ofore pulp (the solid percentage of pulp by weight) amounting to 2% in the case ofore pulp and the density of heavy medium totalling 0.025. We also succeeded in obtaining useful information and data on such items as the method of determination, measuring instruments and apparatus, and source of the γ-rays for use in actual operation.
As we are now continuously undertaking experiments on their application in actual operation basing on these, we are thinking of submitting a further report on them at a later date.

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We studied the effects of current densities on the anodic corrosion of pure leadand silver-containing lead anodes in electrolytic zinc deposition. The results were as follows: With pure lead anode, the lead content of zinc deposit was not materially affected by the current density up to about 4A/dm², but when raised to6-10A/dm², it was considerably increased. The lead contents of zinc deposits at the current density above 6A/dm² decreased rapidly with the increasing silver content of lead anode up to about 0.5%; above this its change became practicallynegligible. The amount of anode slime behaved like this. The anode potential decreased gradually with the increase of silver content of the lead anode.

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