Differential thermal analysis of thermal decomposition of dolomite was performed in air using six kinds of commercial apparatus of our ordinary use. The DTA curves obtained were remarkably varied. These variations could be explained as the effect of the self-generated CO₂. The vapour pressure of CO₂ around the sample was estimated from the curve obtained in comparison with a series of DTA curves reported by Haul and Heystek. It was found that thin layers and the minute amount (less than 10mg) of the sample is essential to minimize the influence of the self-generated atmosphere.
The dolomite decomposition was further investigated by DTA under various CO₂ pressures controlled by the flowing gas method and the static total pressure control, giving the following results;(1) At low CO₂ pressures (20-30mmHg) a negative relationship exists between the peak temperature of the lower peak and the CO₂ pressure.
(2) The shape of the above peak is very sensitive to the change of the CO₂ pressure.
(3) It also changes from broad and unsymmetrical to sharp and symmetrical with decreasing particle size.

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It is well-known that brittle materials such as rocks show time-dependent deformation, and there are a lot of papers which deal with the creep phenomenon and mechanism of such materials. These time-dependent, visco-elastic phenomena, however, have mainly been studied from a phenomenal standpoint Some of them show the fact that the creep is caused by the existence and occurrence of micro-cracks and the extension of them from the experiments detecting the acoustic emission. Furthermore, it is well-known that the time-dependent deformation of brittle materials is closely related to fracturing.
fracturing. The authors have tried to simulate the time-dependent deformations of brittle materials caused by extending numerous inner micro-cracks on the basis of linear fracture mechanics by applying the finite element method. The results of this simulation fairly resemble an actual behavior of hard rocks concerning their time-dependent deformation.
In conclusion, it has become clear that the tertiary creep of brittle materials to be connected with the rupture is due to rapid extension of inner cracks, and that the reason that the compressive strength of such materials is extremely greater than the tensile strength is mainly ascribed to the internal friction which acts so as to obstruct the extension of such cracks.

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Rock can be regarded as a kind of composite material which contains a sufficient number of structural particles with different mechanical properties. Accordingly the rock specimen was divided into 304 triangular elements and the Finite Element Method was used to simulate the failure process. Each element of model rock corresponds to a high or low elastic constant particle. Supposing that the failure process of each element is expressed as a 2-stage, i. e. 1-step Poisson process. a computer simulation of failure and deformation under a constant uniaxial tensile load was carried out by means of the theory of stochastic process and F. E. M.
M. Although each element has a most simple form of probability of survival, the strain-time behavior calculated by this computer simulation shows a similar tendency to that obtained experimentally in primary, steady-state, and tertiary creeps. The P-t diagram calculated, assuming that the model rock specimen is subjected to the eccentric load, shows good agreement to that experimentally obtained P-t diagram.
The P-t diagrams became concave to downward. This result can be explained as probability of survival being expressed by linear combination of two different 1-step-Poisson processes. However, it is apparent from this computer simulation that not only the above mentioned mechanism, but also some extraordinary distributions of stresses caused by inhomogeneity of rock specimen and an eccentric load make the P-t diagram concave to downward.

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The gas flow through a coal bed bearing methane is best considered as a two-step process; firstly diffusion through the micropore structure of the coal and secondly flow along interconnected fissures in the coal bed. As the first step can not be determined practically, it is presented in the form of empirical equation. The factors of the equation to calculate the gas filtration is proposed, and they are compared with theK_t-values of K, Winter's theory. The filtration equation around a borehole is solved by numerical method, and the difference between two cases of no-sorption and simple sorption is discussed.

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Some equations for obtaining the temperature of air at longwall face have been published, but they are unpractical because the heat in the gob which flows into the face and influences the temperature most significantly, has not been considered.
The 76 measured examples of the temperature of air at face in Miike and A. H. IIIEP5AHB's analytical equation for theoretical temperature that treats time factor most appropriately in the published equations, were used in order to put the equation to more practical use.
As a result of investigating many data, an experimental equation was set up to obtain the temperature raised by the heat flow from the gob.
According to the method described in this report, it becomes possible to forecast the temperature practically at the end of face including the heat from the gob. And it is also possible to make clear the problems of temperature rise theoretically and practicable to come into operation an effective measures for high temperature.

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The jet burner is a machine which requires the systematic consideration in design from the disintegration of liquid fuel to the generation of super-sonic jet flame. Until now the optimum operating condition has been experimentally determined and it has been a troublesome work. This paper reports the new method to determine the optimum operating condition of air-kerosene jet burner.
Based on the equation of Pereverzev, which showed that mass exchange rate was dependent on the relative velocity between droplet and surrounding gas. the authors calculated the required length of the rnmbustion chamber.
This calculation made it possible to determine all configurations starting from five initial conditions, which were flow rate of kerosene, injection pressure, spray angle, air-fuel ratio and combustion chamber pressure. The method of calculation and some results are graphically presented and the comparison with the experimental data is made as well.

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Author has been made the calculation and observation for regression lines and coefficient of correlation of 430 examples of Tromp's distribution curves which is obtained from the results of experiment for 53 Nos. of Jig. washers being used in industrial operation.
Basing on these results, author has been observed the statistical testing for distribution of these coefficient of correlation.
As the result of this testing, it is proved that the distribution of coefficient of correlation is subjected to logarithmic normal distribution with size constitution range (Rd) is less than 1.15, where, Rd= (Max. size-Min. size)/average size.
Beside, Ep (Terra coefficient) is represent quartile deviation of logarithmic normal distribution will be represented in the formula [log (D₇₅-1)-log (D₅₀-1)].
Ep will not be representable figure to show the width of distribution for Tromp's curve. I value will be representable value showing the width of distribution, but the absolute figure is completely differ from the Ep value for normal distribution and not be reasonable method representing the separation accuracy.
As a conclusion, author propose a method representing the separation accuracy with standard deviation figure or quartile deviation figure of Tromp's curve.
The appraisement of separating result in case of Rd>1.15 should be calculated by average random variable obtainable from the composited Tromp's curve within Rd<1.15.

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The equilibrium vapour pressure of each synthesizeda rsenate, AlAsO₄, As₂O₅, Co₃As₂O₈, Co₂As₂O₇, CoAs₂O₆, CrAsO₄, FeAsO₄, Ni₃As₂O₈ and Ni₂As₂O₇ has been measured by the transpiration method. For example, AlAsO₄ is assumed to decompose as the following equation.
2AlAsO₄(s) → Al₂O₃(s) + 1/2As₄O₆(g) + O₂(g)
When this reaction occurs in the innert gas, 2P_As4O6 is equal to P_O2. Therefore, the equilibrium constant Kp can be estimated by measuring the equilibrium pressure of As₄O₆ gas. Authors determined the Kp of the decomposition reaction of each arsenate mentioned above, and represented logKp as a function of 1/T.

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The fundamental study was carried out in order to clarify the behavior of arsenic on the calcination of precipitate produced by the removal of arsenic as ferric or calcium arsenate from aqueous solution, and the relationship between the condition of calcination and the redissolution of arsenic was discussed. The results obtained are as follows.
(1) Ferric arsenate precipitate from aqueous solution contained As (III) was amorphous state, but the X-ray diffraction patterns of the calcined precipitates showed the formation of α-Fe₂O₃ at 600°C and FeAsO₄ and Fe₄As₂O₁₁ at 800°C in air. 90% of arsenic in the precipitate vaporized above 600°C in Ar gas stream.
(2) The calcined As (V)-bearing precipitate indicated amorphous state up to 600°C and ferric arsenates at 800°C in air and Ar gas stream, but these compounds decomposed at 1000°C.
(3) The precipitate obtained as calcium arsenate from aqueous solution contained As (III) was Ca₃ (AsO₃) ₂ and that from As (V) solution was Ca₃ (AsO₄) ₂.
(4) When the precipitate of As (III)/Ca molar ratio=1/1 was calcined above 700°C in air, Ca₃ (As0₄) ₂, Ca₅As₄O₁₅ and Ca2As2O7 were formed, and that of As (III)/Ca molar ratios=1/5, 1/10 showed the compounds of Ca₃ (AsO₄) ₂ and Ca₅As₄O₁₅ above 500°C in air.
(5) The calcined precipitate of As (V)/Ca molar ratio=1/1 formed the compounds of Ca₃ (AsO₄) ₂ and Ca₅As₄O₁₅ and that of As (V)/Ca molar ratios=1/5, 1/10 formed Ca₃ (AsO₄) ₂ independent of atmosphere and calcination temperature.
(6) In the redissolution tests of arsenic from the calcined precipitate of ferric arsenate, it was indicated that the arsenic redissolution was suppressed by the crystallization of the precipitate caused by the calcination from 700 to 800°C. However the calcined precipitate of calcium arsenate dissolved the larger amount of arsenic than that of the ferric arsenate.

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本文では中国最大のタングステン鉱山である西華山タングステン鉱山の概況を述べる。この鉱山は1日3, 500tの能力があり, 採掘開始以来産量は多く, 機械化程度も高く, 近代的生産は全中国にとどろいている。

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