In this paper the improvement of the drummy rock detector analyzing an impact sound of rock acoustically and its application test under the underground noise are described.
For the measurement in field as well as in laboratory the circuit set in the detector was improved to have two parallel routes devided from Microphone-Amplifier route. In both routes the signal with original wave form and the signal with filtered wave form of the impact sound of rock were integrated and logarithmically amplified respectively, and then the difference between both signals could be read on voltmeter.
The characteristics of many kind of noises were investigated to know how each of them would disturb to the detection of drummy rock. From this, it was considered that the disturbance by over-all sound pressurel evel is greater than that by the level-difference between the component level of frequency band and the former level. Thus, the disturbance of noises from air-driven machines, i. e. rock drill, is known as the greater one rather than that from the leakage of compressed air and water flow. It was found that the impact sound of rock is not affected by the acoustic characteristic of the underground drift where this investigation was done.
And the detection of drummy rock could be carried out successfully by use of the highly-directional microphone even in trie noise circumstance of 91d B.

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The authors describe a series of laboratory experiments designed to investigate the influence of moisture on the spontaneous heating of coal on a quantitative basis.
The heat produced by the oxidation of coal at 70°C under dry and moist conditions has been measured by D. T. A. specially developed for the investigations. It has been shown that the heat released in dry oxidation is greatest, and it progressively decreases with the increase of the moisture content of coal.

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The impact test has practiced to investigate the decreasing trend of impact value and the maximum elongation rate, on deteriorated wire ropes which have damages such as corrosion, abrasion and wire breakage individually.
From the test, it has become clear that both the impact value and the maximum elongation rate decrease as deterioration of wire rope progresses, and that there is a certain relation between the decreasing trends of them. The relation is realized on both the deteriorated wire rope caused only by one type of damage defected artificially and the retired wire rope which has various types of damage.
The impact value is one of the characteristics that estimate the safety of wire rope, therefore, it seems possible to estimate the safety of wire rope based on the remaining ratio of the maximum elongation rate i. e. the remaining length against the allowable maximum elongation.
But, in case that tht sharp flaws and deteriorations which decrease cross-sectional area of the wire rope partially are recognized on the surface, it may be necessary to practice the manual inspection or some nondestructive testing methods, because the elongation of wire rope is not clearly realized in spite of sharp reduction of the cross-sectional area.

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A study of thermal fracturing of rock requires a value of heat transfer coefficient of fire jet stream injected vertically to the rock: surface. In some investigations till today of thermal fracturing of rock by the fire jet, they use a equation of heat transfer coefficient for turbulent flow over a flat plate.
However, our experimental and analytical investigations of heat transfer indicated that the local heat transfer coefficient was represented by the following equation
N_ux/R_ex^4/5·P_r^1/3=0.05-0.06
and we could not use the flat-plate heat-transfer equation. The authors also showed the data of heat transfer of our air-gasoline thermodrill which was developed in our laboratory and used in piercing and cutting of rocks.

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The decomposition of sulfhydryl collectors, such as xanthate, diethyldithiophosphate (aerofloat) and diethyldithiocarbamate, in acidified aqueous solutions was studied by means of EMF measurement using silver electrode-SCE couple. Rapid responsibility of silver. electrode for the concentration change of sulfhydryl collector anions proved that the EMF measurement served as a convenient technique for studying the decomposition of sulfhydryl collectors, the rates of which were extremely rapid in strong acid solutions.
The rate constants of monomolecular decomposition (k₃) and the dissociation constants (K_a) for xanthic acids were in agreement with those determined by spectrophotometric technique. Diethyldithiophosphate was very stable in strong acid solutions as compared to xanthate and dithiocarbamate; no appreciable EMF change was observed. Diethyldithiocarbamate decomposed in a manner similar to xanthate in acidified solutions; log k₃ and pK_a were found to be 0.89, the same order of magnitude as that of xanthate, and 3. 4, respectively. The activation energy of monomolecular decomposition for both ethyixanthic acid and diethyldithiocarbamic acid was given as 17kcal/mole, indicating that the rate determinig step of acid decomposition for both acids is substantiallythe same irrespective of the difference in their molecular structures.

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Experimental results of a series of studies on the vacuum lift refining of molten blister copper, matte, and white metal, which have been presented in our previous 6-papers, were systematically discussed comparing the D-H process in steelmaking.
Tentative models on the vacuum lift refining of molten matte are subjected to examination and apreferable equation
log=Cη/C₀=-0.434m/MnΣi=1αi
where Co, Cη, M, and m are the initial concentration of an impurity, the final concentration after n times of lifts, the total weight of melt, and the weight of lifted melt, respectively, and α_i is the degree of removal of an impurity at the i-th lift, is quantitatively discussed with regard to the removal of impurities such as Pb, Zn, As, Sb, and Bi.

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The equilibrium diagram of the system ZnO-PbO-SiO₂ was studied by the methods of quenching, differential thermal analysis and X-ray diffraction.
(1) In the system 2PbO·SiO₂-2ZnO·SiO₂, a peritectic reaction (melt+2ZnO·SiO2=PbO·ZnO·SiO₂) was found at about 13% 2ZnO·SiO₂ and 1, 010±5°C. Moreover, an eutectic reaction (melt=2PbO·SiO₂+PbO·ZnO·SiO₂) existed to about 2% 2 ZnO·SiO₂ and 730±3°C.
(2) It was found that only the above 2PbO·SiO₂-2ZnO·SiO₂ system and the compound PbO·ZnO·SiO₂ may be considered besides the three respective binary system.
(3) The limiting solubility of ZnO in the silica-rich PbO-SiO₂ melt determined the silica-saturated eutectic curve in the temperature range of 750 to 1, 300°C.
(4) The isothermal lines of the liquidus surface were obtained in the temperature range of 800 to 1, 200°C.
(5) Moreover, two ternary eutectic and three ternary peritectic-eutectic points were presumed, thus the equilibrium diagram of the system ZnO-PbO-SiO₂ could be established almost completely.

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By using the transportation method, the vapour pressures of Te and Se have been measured for liquid Cu-Te and Cu-Se alloys containing 65 to 100 at% copper, mainly at copper smelting temperature.
The activities of Te and Se in these alloys calculated from the vapour pressures were found to exhibit considerable negative deviations from Raoult's law, and the deviation of ase was larger than that of Te.
The values of γ°_Te for the Cu-Te system are 3.28×10^-2 at 1, 200°C, 2.92×10^-2 at 1, 150°C. On the other hand, for the Cu-Se system, the value of γ°_Se is not determined precisely as in the case of Cu-Te system because of the experimental difficulty associated with the measurements at low selenium concentration, but it is estimated to be 2.0×10^-3 at 1, 200°C. These values suggest that the removal of Te and Se from liquid copper is not so easy as compared with the others.
For the binary alloys between copper and elements belong to the fifth period, the activity curves of these elements in copper rich side show a trend to increase negative deviation from Raoult's law, going to right in the same period.

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