There has been a rapid increase of interest to unconventional methods of fracturing rocks.Particularly, mechanics of thermal fracture, either by the application of direct heat or electrothermal conversion, are most favourable for practice.
In this paper, the authors reported their experiments to measure the strength changes of rocks heated to high temperatures and the thermal fracture.
From the experiments, several fracturing mechanisms of rocks heated to high temperatures were found. Which are;
a) Thermal elastic stresses induced in rock.
b) Transformation of crystal form of the constituting minerals of rock.
c) Decomposition of the constituting minerals.
d) Melting.
e) Thermal expansion of the constituting minerals.
f) Others.
Neverthless these mechanisms are all affecting to thermal fracturing of rock, one of them is a dominant factor to fracture a particular kind of rock by heat, for example b) to granite and c) to limestone.

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In this paper, the fatigue failure of some rocks under the repeated compressive load is discussed from the point of view that the fatigue failure is a stochastic process. Using a graphical method in which the logarithms of the probability of survival are plotted against the fatigue lives, it is revealed that the probability of survival is represented with the sum of two expotential functions, i. e.
p=ξ1·exp (-λ₁·N) +ξ₂·exp (-λ₂·N) where p: the probability of survivalξ_i: the probability that the failure of test piece occurs by the fracture mechamism with the rate constamtλ_i N: the number of loading cycles
This result means that the fatigue failure of rocks consists of two exclusive Poisson's processes of 1st order, each of which would correspond to the inter- and innergranular fracture of the mineral particles constituting the rock.
In order to obtain the S-N curve, the effect of the stress amplitude on the rate constant of the fatigue failure is investigated. A series of experiments is carried out at a constant minimum load and several levels of maximum loads.
Finnally, it is indicated that the loading frequency has a little effect on the fatigue life of the rock.

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In order to make clear the effect of dissolved oxygen in water on the reaction between xanthate and the sulphide mineral, the floatability of minerals, the adsorption density of xanthate on the mineral surfaces and the incipient rate of xanthate adsorptiowere measured in the xanthate solution, the content of the dissolved oxygen in the xanthate solution strictly being prescribed. Then the effects of the dissolved oxygen on the adsorption of thexanthate on the mineral surface were considered on the basis of the reaction rate.
The results obtained are summarized as follows:
1) The flotation rates of the sulphide minerals increasewith increasing the content of dissolved oxygen and become maximum at about 20% dissolved oxygen content with respect to the saturated oxygen content in water. At the oxygen content over 20%, the flotation rate decreases with increasing the content of dissolved oxygen.
2) The adsorption density of xanthate on the sulphide mineral becomes maximum at about 20% dissolved oxygen content in the xanthate solution. This result coincides with the results of flotation rate measurement.
3) The adsorption rate constant, K increases with increasing the content of the dissolvedoxygen until 20% oxygen content, and the value of K divided by the square root of the partial pressure of the dissolved oxygen becomes constant. Thus, the incipient rate of the xanthate adsorption, V_tis shown in the following fomula in terms of xamthate comcentration, X^-and partial pressure of dissolved oxygem PO₂: V_t=k' [PO₂] ^1/2 [X^-] ^m where m and k' are constants. k' corresponds to the coefficient of catalysis.
Accordingly, it is recognized that the dissolved oxygen in the solution accelerates the adsorption of xanthate on sulphide mineral in proportion to the square root of the partial pressure of the dissolved oxygen.

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The actions of sodium sulfite on galena faces have been studied by means of a electron diffraction technique. Interaction of sulfite and xanthate ions with galena depends on a nature of a oxidized state of the cleavage face, pH and a concentration of the reagents. Its primary function on a freshly cleaved face of galena is in a formation of monomolecular film adsorbed on the galenaface. As a substance produced by the action of sodium sulfite onan oxidized face of the galena, lead sulfite is revealed by a electron diffraction technique. Contact angle measurement on the galena face using a captive bubble technique represents that the presence of the sulfite ion in the solution decrease the angle if an oxidized face of the galena is used.

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The prebaked anode consisted of an intimate mixture of titanium dioxide and carbonaceous materials was applied in a small magnesium reduction cell containing fused mixture of magnesium chloride and sodium chloride.
The results are summarized as follows.
1) During the electrolysis, the anode consumes gradually andtitanium tetra-chloride vapour, carbon monoxide and carbon dioxide are detected in the gas exhausted from the anode room of the electrolytic cell. These facts show that free chlorine reacts onthe anode constituents as soon as it is generated by discharge of chloride ion at the anode surface.
2) The titanium tetra-chloride, which is condensed by cooling gas mixture from the anoderoom, will be used as a raw material for metallic titanium production, while magnesium obtained at the iron cathode is a suitable reducing agent to the titanium tetra-chloride. Therefore, the electrolytic extraction process of magnesium by the use of such an anode is closely connected with titanium extraction method called Kroll Process.
3) The most suitable titanium dioxide content of the anode is estimated to be 80 weight per cent at 720°C, close to the bath temperature, by considering the chlorination reaction, Ti0₂-1-(x+y) C+2Cl₂=TiCl₄+x CO₂+yCO and the Boudouard Reaction, C+CO₂⇔2CO. In our experiment, it is observed that free chlorine reacts on the anode almost perfectly, when the titanium oxide content is 50-80 weight per cent.
4) The cathodic currentefficiency was lower than that of the usual I. G. Process, but itwill be possible to raise it by improving operating conditions and the cell construction in a much larger scale electrolysis.

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Activity of each component of liquid copper-silver and copper-tin alloys has been determined by applying the Knudsen effusion technique.
Activities of copper-silver alloys show considerable positive deviations from Raoult's law, and agreed well with the data reported by the other investigators. The activity coefficient of silver at infinite dilution γ°KA g at 1, 100°C was estimated as 5.3. Entropies of mixing calculated from free energies of mixing and calorimetric heats of mixing fit well with the ideal entropies.
Since the effused copper and tin were simultaneously condensed on the wall of silica condenser, respective amounts of these deposits were determined by the atomic absorption spectroscopy. Activities of copper-tin alloys determined satisfied the Gibbs-Duhem relation each other and show considerable negative deviations from Raoult's law. The value of γ°Ksn at 1130°C was estimated as low as 0.093. It was found that the order of activity curves of the alloys between copper and the metals belong to the fifth period such as silver, cadmium, indium, tin, and antimony was the same with one of the periodic chart.
Difference between the behaviors of silver and tin in liquid copper, especially the posibility of the removal of these elements in the copper refining processes, was also discussed from the thermodynamic data obtained in the present investigations.

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