The stresses in the various assumed materials caused by the blasting with two free faces were analysed by using equations derived from the theory of elasticity to present necessary conditions which are required to produce the corner fracture and the data for the stress computation were determined on the basis of those used in our former study with Tako-Sandstone.
The results of the present stress analysis showed that the pattern of the stress distribution in the material was affected with both the physical properties of the material and the blasting condition.
The results obtained in connection with the development of the corner fracture can be summarized as follows;
(1) The stress concentration which is considered to give rise to the corner fracture is chiefly affected with both the Poisson's ratio of the material and the length of the stress wave produced in the material by an explosion.
(2) The development of the corner fracture can not be expected in the material of which Poisson's ratio is less than about 2.5.
(3) When the value of the Poisson's ratio of the material is larger than about 2.5, the development of the corner fracture in the material is controlled by the value of C_f, and there is a possibility of producing the corner fracture for the case of C_f<1.0, but no _possibility for the case of C_f>1.0, where C_f=t_r·C_L/W, and t_ris the rise time of the stress wave, C_L is the velocity of the longitudinal wave and W is the length of the burden.

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The present paper describes the results of theoretical as well as experimental investigations on the disc, ring and indentation tests of rocks. It has been found that the cause of the failure of test pieces subjected to these tests may be in the tensile stress on the plane of fracture, and that the strengths by the disc and indentation tests are fairly near to the tensile strength while the strength by the ring test is far greater than it provided that those strengths are determined by the formula (14) proposed by the authors.

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The temperature difference, Δθdeg generated by the oxidation of coal is expressed for the oxygen contents [O₂]% by equation (1).
The carbon dioxide production X′cc and the carbon monoxide production X′′cc are expressed by equation (2), (3).
The time of temperature rise, [t_s] hrs, is expressed by equation (4).
Δθ=a₁ [O₂] ⁿ (1)
X′=a₂ [O₂] n′(2)
X′′=a₃ [O₂] ^n′′ (3)
[t₂] =a₄ [O₂] ^-n (4)
n, n′, n′′are given by equation (5), (6), (7)
n=2.01-1.56 [C]×10^-2 (5)
n′=2.13-0.02 [C](6)
n′′=2.06-0.02 [C](7)
Where [C]% is carbon contents, and a₁, a₂, a₃, a₄are constant for coal temperature.

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A tecnique of cutting metal by the plasma jet having super-high temperature and large momentum, has been much developed. However, a study on cutting rock-like materials has seldom been done.
Results obtained from this study are as follows; that is, the sectional area of the cut groove is represented by the following equation, which agrees well with practice. whereη=heat transmission efficiency from plasma jet to material cut
H=electric input power=VA/3.6×10⁴v kWh/m
V=voltage, A=ampere, v=feed rate of plasma jetcm/sec
H₀=heat quantity of molten cementm ortarcal/cm³k=thermal conductivity of cement mortar cal/cmsec°C
T_m=melting temperature of cement mortar°C
α=thermal diffusivity of cement mortar cm²/sec

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The separation of copper and zinc minerals in the complex sulphide ores flotation is very difficult on account of the copper activation. Therefore, the deactivation of copper-activated sphalerite is the most important subjects for the complex sulphide ore flotation.
In this study, the deactivation of the copper-activated sphalerite has been investigated in a series of the laboratory experiments.
The effects of H₂SO₄ and Fe⁺⁺⁺ion. in the presence of H₂SO₄ on the deactivation of the copper-activated sphalerite were examined from the flotation test by the Hallimond tube.
From the results obtained, it was recognized that the deactivation of the copper-activated sphalerite could be attained some degree by the 3-;5 vol.% H₂SO₄ solution and could be attained remarkably by the 500-1, 000 mg/l Fe⁺⁺⁺ solution containing H₂SO₄. O₂ gas accelerates the deactivation of the sphalerite in the treatment of the above both solutions. The temperature is one of the important factors for the deactivation.
Then, the dissolution of the copper activated film formed on the sphalerite was investigated. From th result, it was recognized that the copper activated film could be dissolved completely by the Fe⁺⁺⁺solution containing H₂SO₄, and could be dissolved some degree by the H₂SO₄ solution.
The dissolution rate of the activated film was measured as a function of the concentration of Fe⁺⁺⁺ and H₂SO₄ and of the temperature. The dissolution rate is shown by a linear equation. The temperature dependence for the dissolution was pursued.
Using the flotation machine, the differential flotation tests of Cu-Zn sulphide ore were carried out. As the results, the separation of copper and zinc minerals was successful by the deactivation treatment for the Cu-Zn sulphide ore.

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In purification of ZnSO₄ solution on the wet process of electrolytic zinc, it has been thought to be diffcult to remove Co⁺⁺by zinc dust alone.
As reported in the 1st paper, zinc dust named “A type” was developed in Aizu Smelting Plant and this has ability to remove Co⁺⁺in ZnSO₄solution by zinc dust alone.
This zinc dust contains small amounts of Sb and Pb, and the cementation mechanism of Co⁺⁺by this zinc dust was reported in the 1st paper.
The object of this paper is to deliver the rate equation based on the cementation mechanism and to estimate the reaction rate in several cases. It may be concluded from the results of this studies that the cementation mechanism of Co⁺⁺ by zinc dust in the 1st paper is most adequate.
The reaction rate in this paper is estimated as follows.
log x₀-log x=a (1-at) t a=0.064hr^-1
x: concentration of Co⁺⁺
x_o: initial concentration of Co⁺⁺
a: rate constant; t: time
Constitution of rate constant (a)
a =a₁ (T₁-T_o) ⁿ=a₁ (T-45) ²;
T: temperature of solution
a =a₂Z^m=a₂Z^0.78; Z: amount of zinc dust
a =a₃p^l=a₃p^1/2; P: rate of Sb in zinc dust (%)
a =a_4·1/d; d: mean diameter of zinc dust.

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The distribution of tin between liquid lead and iron was studiedat temperatures from 1, 350°C to 1, 500°C. Molten Sn-Fe alloy containing more than 70 at % Fe equilibrates with molten Sn-Pb alloy of which activities can be derived from the results of the 1st report. Because the dissolution of iron can not be ignored in Sn-Pb layer rich in tin, activities were determined in homogeneous Sn-Pb-Fe alloy by transportation method; thus, the reliable values of activity of tin were derived for Sn-Fe alloy. Activities of tin and iron thus obtained exhibit considerable positive deviations from Raoult's law, and activity coefficients of tin and iron at the infinite dilute solutions, γⁿS_n and γⁿF_e, were determined to be 6.4 and 8.4, respectiyely. The actiyities obtained experimentally agree quitewell with those calculated based upon Lumsden's model using miscibility gap suggested by Hansen. The problems of slag loss and refining of metal in tin smelting were discussed using the obtained results.

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It is reported that the Gadeau's bath is more suitable for the aluminum refining when a small amount of sodium chloride is added.
We expected that the addition of some amounts of sodium chloride to the Hoopes' bath (molten salts of sod ium fluoride-barium fluoride-aluminum fluoride system) would be also effective showing the lower melting points of this ternary molten salts as well as the increase of its electric conductivities.
In this paper, the densities and the melting, temperatures of some compositions of the quaternary molten salts, sodium fluoride-sodium chloride-barium fluoride-aluminum fluoride system, were determined.
1) The values of the densities of this quaternary system ranged 2.2-2.9g/cc at 950°C. These values increased with the increase in the content of barium fluoride and decreased with the increase of sodium chloride.
When the content of sodium chloride and barium fluoride is kept constant, the maximum density isobserved at the point where the mol ratio of sodium fluoride andaluminum fluoride corresponds to (3: 1)(3NaF EA1F₃)
2) In this quaternary system, the compound NaBaAlF₆ is assumed to have been formed.
Calculated densities, assuming the additivity of the density of each salt and the formationof compound Na-BaAlF6 accord well with measured ones.
3) Isothermal liquidus line of this quaternry system has a likeness to that of sodium fluoride-barium fluoride-aluminum fluoride ternary system when the content of sodium chloride is kept, constant, but the melting temperatures are lower than the latter on the whole.
And the melting temperatures of two composition ranges are about 750°C.
4) We think that we can use various compositions of this quaternary molten salts as an electrolyte of aluminum refining as far as densities and melting temperatures are concerned.

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