The effect of pore pressure on the mechanical behaviour of rocks has been investigated in order to confirm the validity of the effective confining pressure law among rocks with various properties and textures. The triaxial compression tests of Noboribetsu tuff, Horonai sandstone and Akiyoshi marble were carried out with servo-controlled facilities for confining pressure and pore pressure combined with a conventional hydraulic testing machine. The stress strain curves of the three kinds of rocks were determined over the full range of deformation involving both pre-and post failure regions under the condition of confining pressure and pore pressure extending up to 700kg/cm².
The experiment showed that the effective confining pressure law was valid for Noboribetsu tuff and Horonai sandstone but the fracture criterion of Akiyoshi marble was scarecely explained by this hypothesis at the strain rate of 6×10^-5/sec. Since the tuff and the sandstone were more porous and permeable than the marble, this hyposesis seems to be more realistic to rocks whose pores are fully interconnected. Concerning the marble the effective confining pressure law may be gradually valid with the decrease of strain rate.

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The state around borehole in a coal seam is considered as shown in Fig. 1. This state can be expressed by the simple model as shown in Fig. 2. In this model the gas flow from coal seam to the borehole is considered as consisting of the Kiyoshi HIGUCHI1, Toshiro ISOBE2 and Kotaro OHGA3two-courses; one is direct radial flow toward the borehole, the other is linear flow toward the discoidal fracture.
The total gas flow from the borehole including these two-flows is expressed by the equation (2).
This partial differential equation is solved numerically by using a digital computer.
From the comparison of the calculated results with the observed values following results are obtairled.
Permeability of the coal seam in YUBARI district is smaller than that of the KITASORACHI district, but r₁ value (the apparent radius of the discoidal fracture) of the coal seam in YUBARI district is larger than that of the KITASORACHI district.
The larger the r₁ value, the more easily methane in the coal seam can be drained.

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In predicting the temperature of ventilation air in practice, it is necessary to take into consideration the variation of air temperature at the entrance, caused by atmospheric conditions and artificial ones such as the change of ventilation net work and the installation of cooling units. In the present paper the effect of variation of the air temperature at the entrance on the air temperature along the roadway are theoretically analysed.
A general expression, Eq.(20), is first obtained for the temperature along the roadway when the air temperature at the entrance changes arbitrarily. Then numerical values of Eq.(20) are calculated for two practical cases: sinusodial and sudden changes of the temperature at the entrance. Results of the discussion are as follows;
(a) In the case of the sinusoidal air temperature change at the entrance, the temperature of ventilation air shows a transient state at the beginning of ventilation, but then reaches some sinusodial state of variation which is expressed by Eq.(29). The amplitude is reduced and the phase delayed as the distance from the entrance increases. The temperature of ventilation air can be approximated by Eq.(29) after about one year from the start of ventilation.
(b) The effect of a sudden air temperature change at the entrance is instantaneous on the temperature of ventilation air at a short distance from the entrance and is gradual as the distance increases. Two practical approximate equations for this case are proposed.

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In this paper, the experimental measurements were made for slurry by the comparison and the unsteady hot-wire (probe) method, and the applicability of predicting equations was discussed by comparison between experimental data and predicted values.
The main results obtained are as follows:
(1) The measured values obtained by two methods noted above are quite agreeable for equal λ_d values.
(2) The formula proposed by the author predicts the effective thermal conductivity of slurry very well with the maximum error of about ±15%. It may be concluded that author's predicting equation has a wider range of applicability than the previous formulae.

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In this report, the writer go further than the view point of 2nd report, and has made clear the relation between wettability of coal and oxygen functional group in coal.(See Fig. 3-10.)
He has concluded as follows;
In the case of bituminous coals, their wettabilities have no correlation with their oxygen functional groups without hydroxyl groups.
On the other hand, in the case of brown coals, their wettabilities have correlation with their oxygen functional groups.(Concerning carboxyl groups, healready mentioned this point in the 2nd report.)
On above-mentioned point of view, he has added the information from model materials of Table 2.(There are more model materials than ones in the 2nd report.)
Besides, he has submitted the reformative result of the pyrolysis reaction which remove oxygen functional group in low-rank coal by autoclave.(See Table 3-4, and Fig. 12-14.)

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Collection of galena by dithiophosphates has been investigated by means of adsorption measurements and flotation tests, using an artificial galena and various dithiophosphates whose alkyl chain length ranges from C₂ to C₅. The artificial galena is very fine powder (specific surface area: 1.3m²/g) possessing the structure of natural galena.
Experimental results are as follows:
The adsorption isotherm of dithiophosphate on galena gives straight line on a log-log plot up to the concentration above which the amount taken up is saturated. The saturation amount is independent of the kind of alkyl group. Although the slope of the adsorption isotherm is unchanged with length of alkyl chain, the slope of iso compound is steeper than that of normal compound. The equilibrium concentration above which the amount taken up is saturated decreases with increasing length of alkyl chain and the amount of iso compound taken up is saturated at lower equilibrium concentration than that of normal compound with the same number of carbon atoms.
When dithiophosphate is adsorbed on galena surface, considerable amounts of lead dithiophosphate are deposited on the surface. While in the case of xanthate adsorption, the amount of lead xanthate deposited is very small. These results indicate that xanthate depresses the oxidation of galena surface more strongly than dithiophosphate. This may be related to more rapid adsorption and stronger reducibility of xanthate.
On the basis of the complete monolayer adsorption and the specific surface area of the sample, it is calculated that the cross sectional area per molecule of dithiophosphate adsorbed is 35.4 A² and that of xanthate is 27 A². The cross sectional area of dithiophosphate adsorbed is good agreement with that of a model proposed by Hagihara, et al.
As the chain length increases, there is a decrease in the concentration and the uptake of dithiophosphate at which complete flotation recovery is obtained. Iso compound gives complete flotation recovery at lower concentration and uptake than normal dithiophosphate with the same number of carbon atoms.
The concentration of ethyl xanthate at which complete flotation recovery is obtained is lower than that of diethyl dithiophosphate. But, in this case, the uptake of the former is higher than that of the latter.

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The e. m. f., s of galvanicells with the solid-oxide electrolyte (ZrO₂+Y₂O₃) were measured to determine the activities of components in the Pb-Sn, Pb-Sb alloys and PbO-Sb₂O₃ slags in equilibrium with Pb-Sb alloys at the low temperature range of 673-1073 K and the various thermodynamic values were also calculated.
The cell used were as follows:
(+) Pt, Ir/Pb.PbO/ZrO₂+Y₂O₃/Sn. SnO₂/Mo or Re, Fe-Cr (-)
(+) Pt, Ir/Pb. PbO/ZrO₂+Y₂O₃/Sn-Pb. SnO₂/Re, Fe-Cr (-)
(+) Pt, Ir/Pb. PbO/ZrO₂+Y₂O₃/Pb-Sb. PbO-Sb₂O₃/Re, Fe-Cr (-)
From the present experiments, the following conclusions were obtained.
1) The standard free energy of formation of SnO₂ was shown by ΔG°SnO₂ (kJ/mol) =-569.6+0.2018T (k)±0.54 in the temperature range of 773-1165 K.
2) The activities of Sn in liquid Pb-Sn alloys at 823 and 1073 K showed a slight positive deviation from Raoult's law at low Sn concentrations and obeyed Raoult's law at high Sn concentrations. These results agreed very closely with the data by Das et al.
3) Several integral thermodynamic quantities of Pb-Sn alloys were calculated and compared with the selected values by Hultgren et al.
4) The activities of Pb and Sb in the Pb-Sb alloys at 893 K showed a slight negative deviations from Raoult's law. These results were in good agreement with other reliable data.
5) The activities of PbO and Sb₂O₃ in the PbO-Sb₂O₃ and PbO-SbO_1.5 slags at 1023 K showed a considerable large negative deviations from Raoult's law.
6) The liquidus curves of Pb-Sb and PbO-Sb₂O₃ were determined and compared with those of other authors.

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The distributions of As, Sb and Bi between molten copper and white metal were separately investigated at varying element concentrations and temperatures. Distribution coefficients for all three elements, defined as solubility in copper divided by solubility in white metal, were found to be greater than unity and to decrease with increasing concentrations of the elements in copper and/or with increasing temperature. A tentative thermodynamic explanation of the influence of concentration changes of the elements is presented.

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Phase equilibria in the system Pb-S-O were investigated in the temperature range 600 to 1050°C at one atmospheric pressure. Nine univariant equilibria were determined by the measurements of the equilibrium oxygen partial pressures using the following galvanic cell.
Air ΙZr₂O (+CaO)Ι Condensed phase I, Condensed phase II, Gas
A consistent potential phase diagram for the system was constructed based on the present experimental results and available thermochemical relations. The Gibbs energy of formation of the compound PbSO₄, PbSO₄·PbO, PbSO₄·2PbO were evaluated from the data. Phase boundary between Pb (1) and PbSO₄-PbO (1) was estimated based on the solution model for PbSO₄-PbO (1) reported by Jacob and Toguri, and it was found to be fairly well consistent with the experimental result. Sulfur partial pressures at the Pb (1)-PbS (s) phase boundary calculated from the model of Schuhmann et al. was also in good agreement with the experimentally determined values.

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