The Hoskold's Formula, concerning evaluation of mine-lot, heretoofre in use in the world as well as in Japan, is not particularly adequate under the present circumstances of Japanese coal mining industry.
We, therefore, suggest new method oneit, which should be well-fit for the actual circumstances of our industry, by the reason of adoption of consideration for many particular facts, namely the special treatment of the depreciation practices (i. e. partialy treated as production cost), relation between capital and loan, and reserves.
Main elements of new method are as follow;
1. In case of evaluation of invested capital, capital and loans are devided.
2. Depreciations are fully practiced up to legal limit, but not like as the sinking-fund method of Hoskold Formula.
3. In the Hoskold method, it is not clear on standard of renumerative ratio and degree of minin grisk, therefore in the new method it represents respectively by the words of the rate of dividends and reserves to the net worth.

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Full instrumentation is made on a medium size boring machine to speed up the experiments and to get more precise data. Penetration rate, torque, thrust and pressure of water supply can be recorded automatically on four channel pen-writing oscillograph. All results are of laboratory studies bored into the rock specimens ranging from hard to soft formations. Diamond bit used is a surface setting core bit, 46mm in size, having 12 carat setting. Rotation speed and volume of water supply are variable as parameter. Main results obtained from these experiments are as follows:
1) Penetration rate is almost proportional to thrust and rotation speed of bit
2) Relation between thrust and torque is almost constant for all rocks and this relation does not change by rotation speed.
3) Max. penetration rate is proportional to volume of water supply in the case of the rotation speed i constant.
4) Max. penetration rate is proportional to square root of rotation speed and the max. thrust corresponding to max. penetration rate is inversely proportional to square root of rotation speed.
5) Penetration rate and max. thrust for each rock can be presumed from the shore hardness, indentation depth and compressive strength of the rock.

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This investigation was undertaken to observe the Phenomena of Spontaneous combustion inside the sealed area after sealing and to study the conditions of fire-reappearance when opening the sealed area (using special furnace).
The main results obtained are as follows;
1) Considering the mechanism of spontaneous combustion, it is natural that the phenomena inside the sealed area should develope toward inlet.
2) From the studies of the phenomena inside the sealed area which permits air to get into freely, we may suggest a possible type for the heat accumulation in the large coal-pile.
3) It is provable that some portion of coal-pile becomes very reactive toward oxygen during sealing period so that the fire starts again at this portion easily when opening the area.

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O. S. type vanner, newly developed by T. Oyama and K. Sasagawa, is a machine ofhigh capacitywhich is. doing satisfactory work in the roughing of low grade sandy ores.
It has the special construction which applies the principle of consolidation trickling- for stratifying the pulp on the endless belt. The upper side of endless belt is bent at the almost central position, so as to make a deep trickling bed, and the vibrator is also provided under the upper belt atthe position of the trickling pool, to make the thick bed loose and to accelerate the trickling velocity of heavy minerals through the interstices of light gangues.
Many tests were carried out upon the low grade ores of magnetite-sand, titaniferous-magnetite sand, manganese ore, coal etc, , to know the behavior of consolidation trickling and the characteristics of the vanner. This paper shows the results obtained with the low grade ore of magnetite-sand, as an example of tests.

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Supersonic coagulation process seems to be one of the most promising applications of the supersonic energy to mineral dressing. However, its further developments on the industrial scale have been kept back on account of the poor knowledge of the basic principles involved in that process. The authors studied the fundamental mechanism underlying the phenomenon of supersonic coagulation, with particular reference to the electro-kinetic theory of flocculation which has made a great progress in the field of colloid chemistry. In this connection, the function of the supersonic waves for flocculation is considered mainly to supply the mineral particles with the energy which is required to surpass the potential barrier to flocculation, while the function of the flocculating agents is, in general, to change the shape of the flocculation potential curve.
Irradiation experiments were performed on the suspensions of quartz in pure water or in water modified with various reagents such as HCI, NaOH, dodecylammonium acetate, Separan and MIBC, under various frequencies (0.6-4.0 Mc/s) and controlled intensities of the supersonic waves. Consideration of the experimental results in the light of the “flocculation energy” lead to the conclusion as follows:
(1) The differential vibration among the liquid and the mineral particles plays little part in the supersonic coagulation of aqueous suspensions.
(2) The role of the radiation pressure due to standing waves is dominant in supersonic flocculation phenomena, especially when the suspension has a great tendency to dispersion.
(3) Hydrostatic attraction among the particles, which is caused, according to the theorem of Bernoulli, by the rapid flow of the liquid in the voids, is supposed to play the part of compacting the flocs. This effect will be more pronounced in the case of the suspensions with a great tendency to flocculation, where large flocs (up to several millimeters) are observed.
(4) Effect of surface activity of supersonic waves on flocculation could not be established in so far as the authors' experiments were concerned.
Suggestions were also given which will do for the industrial applications of supersonic flocculation process of the liquid-solid system.

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Among the impurities in titanium tetrachloride, the solubilities of silicium chloride, ferric chloride, vanadium chloride and etc., have already been determined. In the chlorination of high titanium slag, however, the other impurities except those above mentioned might be appeared.
In this report, the author studied the solubilities of calcium chloride, manganese chloride, magnesium chloride, aluminum chloride and chromium chloride at various temperatures. Calcium chloride has its solubility of 0.105%(Ca/Ti weight%) at 14°Cand 0.135% at 80°C: Magnesium chloride shows almost no solubility: Aluminium chloride has 0.0115%(Al/Ti weight%) at 20°C and 0.0170% at 78°C: Manganese chloride has 0.029%(Mn/Ti weight%) at 14°C and 0.055% at 80°C: Chromic chloride shows almost no solubility and its amount can be detected only by spectroanalysis.

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