It is well known that when “Low” explosives are deflagrated in a material, radial cracks are produced from the inner surface of the charge hole. The growing directions of these radial cracks could not be predicted normally, but it might be useful if we could control such growing directions. Therefore, in this paper, the possibility to control the directions of radial cracks has been discussed by using the results of the stress analysis which was undertaken by using the finite element method and also those of the experiments.
As the results, it was concluded both theoretically and experimentally that for the case that the material was broken by the quasi-static gas pressure of “Low” explosives, in other words, “Low” explosives of which rate of deflagration was less than about 300m/s were used, the direction of the radial cracks could be controlled by using a specially designed cartridge of which sectional shape was shown in Fig. 1 (a). Namely, the cement mortar block was separated clearly into two parts, as if it was cut out with a knife, by the explosion of a specially designed cartridge of the “Low” explosives of which rate of deflagration was about 100m/s, and no radial cracks towards the undesired directions were observed. Furthermore, the reason why the directions of the cracks were controlled was clarified by the results of the stress analysis.

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The reactions of Cu (II) ion with sulfhydryl collectors were investigated by means of the spectroscopic methods.
From ESR and UV measurements of the reactions products between Cu (I) ion and disulfides in benzen solution at 25°C, the formation of Cu (II) xanthates and Cu (II) aerofloates was confirmed and the stability constant of Cu (EAf) ₂ was obtained to be -1.5×10⁵l/mol.
The determination of Cu (II) species on the copper bearing minerals which had been proposed by Solozhenkin and Kopitsia using ESR was discussed from view point of the new equilibria between Cu (I), Cu (II) species and disulfide in benzen solution.

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The basic flotation characteristics of garnet, zircon, ilmenite and magnetite were determined by floatability and flocculation measurements and infrared measurements with various 18-carbon fatty acids and tall oils.
The effect of fatty acid on the floatability and flocculation of garnet, zircon, magnetite and ilmenite decreases in the following order: linolenic→linoleic→oleic acid at pH values less than about 10, while at higher pH ranges, the above order is reversed. The critical pH values for the minerals with 10^-4mol/lof fatty acids and 50mg/lof crude tall oil indicate the following order of float ability: monazite>garnet>zircon, magnetite, ilmenite in the alkaline side, and zircon, magnetite>garnet>ilmenite in the acid side.
The pH dependence of the floatability and flocculation behaviour of the minerals and the infrared observations for oleic acid adsorbed on magnetite indicate that both chemisorption and physical adsorption of collector would take place on the mineral surface.
Also, the selectivity of fatty acids on the above minerals was discussed by practical tests on Beach sand.

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The depression of pyrite with lime in xanthate flotation was investigated by means of flotation tests, adsorption studies and electrokinetic potential measurements.
The results obtained are summarized as follows: 1. In xanthate flotation of pyrite, lime is more effective than sodium hydroxide as a depressant.
2. Ca²⁺ions do not affect the adsorption of xanthate on pyrite; the adsorption amount of xanthate decreases with increasing pH of solutions.
3. The adsorption of Ca²⁺ions on pyrite is relatively small in the range of pH5 to 7, while the adsorption of Ca²⁺ions increases rapidly as the alkalinity of solutions increases. The adsorption of Ca²⁺ions are not affected by the presence of xanthate.
4. The pH value at which the zeta-potential of pyrite bacomes zero is found to be 7.6; above and below which pyrite is negatively and positively charged, respectively. It is observed that the sign of the zeta-potential of pyrite is reversed by the addition of Ca²⁺ions in the range of pH above 7.6, i. e. the range where pyrite is negatively charged. This may be interpreted in terms of the specific adsorption of Ca²⁺ions on pyrite surfaces.
5. MgCl2 is more effective depressant than CaCl2 under the conditions in which the-pH of solutions was adjusted by NaOH. As in the case of Ca²⁺ions, the adsorptions of xanthate on pyrite is not affected by the presence of Mg²⁺ions.
6. The adsorption of Mg²⁺ions on pyrite becomes significant with increasing pH of solutions, while no appreciable change in the adsorption amount of Mg²⁺ions takes place in neutral pH regions. Based on the above results the following conclusions may be obtained.
A. The adsorption of Ca²⁺ions is responsible for the depression of pyrite. The depression of pyrite may be caused not by the formation of calcium sulfate or calcium carbonate of pyrite surfaces but by the adsorption of Ca²⁺ions asscciated with OH^-ions.
B. The adsorption of xanthate and Ca²⁺ions takes place independently on the surfaces of pyrite. The floatability of pyrite depends upon the relative adsorption amounts of xanthate and Ca²⁺ions; the former makes the surfaces of pyrite hydrophobic, while the latter makes them hydrophilic.

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The present study was undertaken to investigate the kinetics of deoxidation of liquid copper by hydrogen. The oxygen concentration of liquid copper was measured continuously by EMF of the following oxygen concentration cell.
Pt, Cr₂O₃+ Al₂O₃, O (in Cu)/ZrO₂(+CaO)/ air, Pt
A series of experiments was carried out under the following conditions, the initial oxygen content was about 1500-2000ppm, the mixing ratio of argon and hydrogen gases was in the range of PH₂=0.05-1 atm, and the temperature was changed 1153, 1192 and 1251°C.
From experimental results the rate of deoxidation was found to be dependent on the partial pressure of hydrogen and was to be independent on the temperature. Also it was found that the present experimental results could not be explained by a simple mechanism, such as the diffusion of oxygen or hydrogen atom in liquid copper or the chemical reaction controll. Such a fast deoxidation rate was assumed to be based on the stirring of liquid copper even if the deoxidation reaction proceeded out at the comparatively quiescent state.

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