The influence of salt concentration in solution being contained in Ohya Tuff samples on their stress-strain diagrams has been investigated.
The results are as follows.1. The stress-strain diagrams of Ohya Tuff samples saturated with Nacl solution are different from the stress-strain diagrams of its dry samples.
The stress-strain diagrams of dry samples are almost linear, but the stress-strain diagrams of the samples saturated with each solution indicate first under bulgy curves, and then, from one point to failure, above bulgy curves, so called S type curves.
2. The stress-strain diagrams of the samples saturated with each solution indicate S type curves and the strain at the situation of the point changing the bulge of curves becomes almost equal to the vertical strain caused by expanding. And, the compression of first step and second step are defined on the stress-strain diagrams.
3. A secant Young's modulus in the compression of first step, E₁ (Kg/cm²), and a secant Young's modulus in the compression of second step, E₂ (Kg/cm²), are defined. When NaC1 concentration in solution became dilute, E₁ and E₂ for Ohya Tuff indicated the tendency of a decline. And, the rate of a decline for E₂ was lower than that for E₁. These tendency were explained by the degree of becoming soft based on the expanding of soft rocks saturated with solution.
4. When NaCl concentration in solution being contained in samples heated becomes dilute, their secant Young's moduli do not indicate any change.

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The present paper describes fundamental studies on an improved practical method for the prediction of air temperature and humidity along a wet roadway.
Discussions are made on the mathematical expressions of heat and mass (moisture) transfer at a roadway surface and it is shown that by introducing “modified air temperature” the equation at the surface in the wet roadway can be transformed into the same form as in the dry roadway. Then a simplified practical method for calculating the air temperature and humidity is developed, using the concept of modified air temperature.
Finally a method for the estimation of wetness fraction of roadway from measured values of temperature and humidity of ventilation air is proposed.

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A fundamental study on impact cutting were carried out together with the conventional cutting with a drag bit. An electric motor hammer which blows at 3000 blow/min with 6.6J per blow was used to supply impact to a bit of 15 mm blade width. Four samples of which uniaxial strength ranges between 43 and 84 MPa were tested.
It was found that excavated volume per blow took the maximum and specific energy took the minimum at an attack angle which differs from sample to sample. On the other hand, with changes of cutting force, excavated volume per blow and specific energy were maintained almost constant.
Comparing with the conventional cutting with a drag bit, at least, 75% reduction of cutting force and 80% reduction of thrust force were found to be possible by the impact cutting, though specific energy was slightly larger than that of static cutting in case of a new bit with sharp cutting edge.
With a worn bit of 2-5 mm wear flat, reduction of cutting and thrust forces were more prominent. And in this case, specific energy in the impact cutting was much less than that of static cutting.

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The authors developed the chain system sedimentation balance (CSB) and the electromagnetic sedimentation balance (ESB) for the analysis of particle size distribution of powder in 1975 and 1982, respectively.They later developed the improved sedimentation balance (ISB) which is an improved version of the above apparatuses.The present paper describes the outline of the apparatus and the reproducibility of measurements by the ISB.
(1) The ISB has a maximum weighing load of 200 g and weight detection sensitivity of 0.1mg.
(2) In order to prevent the effect of room temperature variation, heat transfer from the room to the balance box was cut off by covering the apparatus with a styrene resin plate containing air bubbles.The zero point of the balance was maintained constant for a long period during measurement.
(3) It was confirmed that the effect of disturbance from the water made by stirring before measurement was limited to within three minutes from the beginning of the measurement.
(4) Particle size distribution analysis of quartz powder was repeated 10 times.There was very good agreement betweenall the particle size distribution curves obtained by the ISB, the ESB and the CSB.
(5) The ratio of the weight of the suspended solids which actually settled on the weighing pan to that of the ideal weight was calculated. The ratios, in percentage were 78.3±2.3, 77.0±3.1and79.6± 1.5 for the ISB, the ESB and the CSB, respectively.It would therefore mean that the reproducibility of measurement by the ISB is intermediate between those by the ESB and the CSB.
(6) A numerical calculation for the analysis of a measured sedimentation curve was developed.The particle size distribution curves obtained by numerical calculation and by graphical analysis agreed with each other very well.

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The flotation separation of hematite and dickite finer than 2μm has been investigated by using a pressure type and a Denver type flotators.Flotation tests were carried out by activating dickite with calcium chloride, followed by adding sodium oleate as a collector.
In both pressure type and Denver type flotation, the separation of dickite from hematite was not achieved, because the addition of calcium chloride increased the floatability of hematite as well as dickite.However, in the case of the pressure type flotation, dickite could be selectively floated from hematite by adding Proper amounts of Separan AP30 (an anionicpolymeric flocculabt) and sodium oleate in the presence of asmall amount of calcium chloride at pH 8 to11. 5.The selective flotation of dickite from hematite by the pressure type flotation may be explained by the following reasons: the preferential adsorption of calcium species on dickite occurs due to its cation exchangeability in the presence of a small amount of calcium chloride at moderately alkaline pH and then hydrophobic flocs of dickite is formed as the result of the increased adsorption of Separan AP30 and oleate ion on the calcium activated dickite surface.The best separation result was obtained at low pulp density of about 1%.

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The equilibrium between the molten system of Na₂CO₃-Na₂O-SiO₂ and metallic copper was studied at 1250°Cunder a flow of argon gas. The results are as follows:
1) Two miscibility gaps were observed and the conjugate relations were established. One is the miscibility gap between sodium carbonate salt and Cu, O-base slag and another is between sodium silicate slag and Cu₂O-hase slag.
2) Copper solubility in the melts of Na₂CO₃-Na₂O-SiO₂ was determined. The copper solubility in Na₂CO₃ melt is very small and copper is the most soluble to the slag near 0.7 soda-ratio.
3) Activity coefficient of CuO0.5 in this system was calculated, based on the data of the copper solubility.
4) From the relation between the amount of retained CO₂ in slag and the amount of added acidic oxides, it can be concluded that two moles of Na₂CO₃ are decomposed by one mole of SiO₂ and three moles of Na₂CO₃ are decomposed by one mole of As₂O₅ or Sb₂O₅.

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