The interpretation of electrical anomalies in the electrical prospecting is very difficult to analyze the general problem of any resistivity distribution. The analog computer and the interpretation method by the analog computer have been studied by the author and his assistants since 1954 and “Interpretation of Electrical Prospecting by Analog Computer” was published in Journal of the Mining and Metallurgical Institute of Japan Vol.85, No.975, 1969.
In this paper, the author intends to expain the basic concepts and the basic methods in the interpretation method using the analog computer.
The basic concepts are the unit element and the unit volume, and the sensitivity curves and the sensitivity distributions of the above-mentioned element and volume. The basic methods are the prospecting range method, the structure composition method, the electrode composition method, the input resistance method and so on. In this paper, the basic concepts and the three basic methods are explained.

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A sound velocity measurement was successfully carried out on the mine pillar of the Kawayama mine by using the sonic system reported in the 1st report.
report. Besides the field measurement, laboratory tests were performed for gathering informations of the effect of cracks or pressures to the sound propagation velocity in rocks. In the tests, several rock blocks, about 25×20×20 cm in size, were prepared and sound velocities were measured in the perpendicular direction to the applied vertical pressure.
Considerable velocity decreases were observed on the sandstone and taff. Slightly decreasing velocity change was found on the Kawayama phyllite just before its failure. On the Ashio liparite, however, no velocity change was observed up to the failure. Finally, based on the both measurements, a discussion on seismic field study for the state of stresses or cracks of rock around mining openings was done.

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In this paper, we present the results of the experimental investigation of the relation between average heat transfer coefficient and friction coefficient in rough model circular airway having ring type roughness elements with semicircular cross-section, as a series of previous reports.
Measurements were carried out under the condition of heating air in the airway which was heated in its whole length by isothermal hot water.
Results were obtained for Reynolds number Re from 4.0×10³ to 9.0×10⁴ at a Prandtl number P_r equal to 0.71 and roughness-height-to-diameter ratio h/D from 0.0408 to 0.122.
The following experimental formula was also obtained for circular airway as well as the cases having ring type roughness elements with isosceles triangular cross-section and rectangular one as reported in the previous papers: N_um=CR_e*^m P_r^0.5
In the above expression Num is Nusselt number based on effective heat transfer area A_m, R_e* is modified Reynolds number defiened by friction velocity, and further C and m are constants related to the roughness ratio h/D and the shape of the roughness element as given in Fig. 15.

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The electron diffractive investigation which related to the researches of the surface reactions with special reference to the flotation mechanism of sphalerite has been extended to the case of the artificial zinc sulfide and cadmium sulfide.
1) It has been confirmed that aqueous solutions of silver nitrate and lead acetate react with the artificial zinc sulfide to produce well developed crystallite of metallic silver and a lead sulfide at room temperature, respectively. In aqueous solution of copper (II) sulfate and cadmium sulfate crystallites of reaction product were not produced on the zinc sulfide at room temperature.
2) In aqueous solution of silver nitrate, a crystallite of silver sulfide was produced on cadmium sulfide at room temperature. But in an aqueous copper (II) sulfate solution the crystallite of copper sulfide was not produced.
3) At a temperature over 80°C, all of the products that were not obtained in crystallites at room temperature were obtained as crystallites. In an aqueous cadmium sulfate solution, cadmium sulfide was produced on the zinc sulfide. In a copper (II) sulfate solution, copper sulfide of zinc sulfide type was produced at early reaction time, and a copper sulfide of covellite type was obtained successively on the zine sulfide or cadmium sulfide.
4) In an aqueous copper (II) sulfate solution, copper sulfide of covellite type was obtained on an evaporated film of zinc sulfide at room temperature by surface properties of the zinc sulfide (e.g., cleavage face of single crystal, artificial powder, evaporated film, etc).

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Green copper ore is one of the typical oxidized copper ore and it usually contains malachite and chrysocolla. Generally, copper carbonate minerals are recovered by sulfidizing flotation with xanthate type collector, however, copper silicate minerals are not separated efficiently by flotation. Fatty acid flotation is also applied to green copper ore, but separation of calcite is very difficult under any flotation conditions.
The ore samples tested are composed of malachite and crysocolla accompanying calcite, quartz, andradite and a little quantity of mica. Malachite is usually needle crystal, fibrous aggregate, crust, vein or tiny grain and is finely intermixed with chrysocolla.
chrysocolla. Solubilities of copper minerals in ammonium hydroxide were studied and it was found that malachite is soluble easily, on the contrary, chrysocolla is only soluble by adding of ammonium salts such as ammonium chloride or ammonium sulfate. Proportions of malachite and chrysocolla in an ore can be determined quickly according to difference of the solubility.
Sulfidizing flotation process was applied to the ore and favourable performance was obtained by stage flotation using sodium sulfide and mercaptobenzothiazole. Some flotation results and their conditions were described.

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The kinetics of dissolution of silver in ammonia solutions under oxygen pressure have been investigated with a view of establishing the factors which influence the dissolution rate. The results indicate that the rate is determined by the following factors:
1) the fraction of surface sites covered with oxyge
2) the concentration of ammonia
3) the temperature
4) the additional quantities of sodium thiosulphate.
Based on this investigation, the zinc leach residues have been leached with 7.5M ammonia solution at a temperature between 175 and 200°C and an oxygen partial pressure of 15kg/cm². Gold and silver extractions of over 95 per cent were obtained.

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A new refining method, a fused salt electrolysis with amalgam, has been proposed in this investigation to obtain high-purity indium from a mixed amalgam of tin and indium. It was known that high-purity indium was separated efficiently from the mixed amalgam. The following results were obtained.
1) The most suitable electrolyte composition for the electrolysis was 51.6 mole% AICl₃, 4.6 mole% InCl and 43.8 mole% NaCl. In this electrolyte, In-Hg was greatly lessnoble than Sn-Hg or Hg, and In was much noble than Al or Na; therefore, it was suggested that only indium was dissolved at the anode and deposited at the cathode during the electrolysis.
2) The fused salt electrolysis with amalgam was performed at 180°C in the electrolyte mentioned above by use of the mixed amalgam (Sn: 1.0wt%, In: 10wt%) as the anode and indium as the cathode. As we suggested above, pure indium could be obtained from this mixed amalgam at high current densities (17.6-26.5 A/dm²). The current efficiencies were 100% at the anode and were 76-78% at the cathode.

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Deposited silicon rods of 600mm in length and 25mm in diameter were produced by the reaction of trichlorosilane with hydrogen on the thin rods maintained at the temperature of 1100-1150°C by direct passage of electric current. A water cooled reaction vessel of stainless steel containing two silicon rods was used. The silicon rods were preheated by radiation from a heater contained in the reaction vessel and successively heated up to the definited temperature by direct passage of electric current from the circuit having a saturable reactor. The ratio of hydrogen to trichlorosilane were 10-20 and the rate of feeding the trichlorosilane was 0.0378 mole /h·cm² (surface area of silicon rod). The yields of silicon from the trichlorosilane were 25-30%. The growing rates of the diameter of silicon rods were about 0.225mm/h. The electric power reqired for the deposition were 1.0-0.9kWh/g Si and the electric current for heating the silicon rods of 4mm×4mm were about 40A and 350-400A for 25mm in diameter. The trichlorosilane and silicon tetrachloride contained in the outlet gases were caught in a cold trap maintained at about -70°C and analyzed by fractional distilation. From these results, it was revealed that about 30% of the feeded trichlorosilane was converted to deposited silicon, 20% to silicon tetrachloride and 50% was retained as unchanged trichlorosilane. These silicon rods had n type resistvities higher than 150 ohm cm and life time of 200μsec after 2 zone passes of floating zone refining in argon.

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