The authors observed the relationship between the bucket behavior and three bucket attachment systems on the sediments of the indoor horizontal test tank. The bucket attachment systems are illustrated in Fig.2, i. e. balance attachment, oblique attachment and one side attachment.
When bucket was dragged out on the sediments, the contact of buckets was often observed because of overturning of bucket as shown in Fig.7, in case of balance attachment.
Oblique attachment had been adopted in order to widen the distance between the descending and ascending lines in water, but it was scarcely possible to recognize this effect except using heavier buckets. This attachment system, however, was so effective for turning movement on sea bottom as shown in Hg. 17, that the bucket did not contact each other.
In case of one side attachment. thoueh the contact of buckets was also observed as Figs.18 and 19, the bucket took steady recovery form on the sediments when the distance between the descending and ascending lines was largely widened on the bottom. Therefore, one side attachment should be auoptea, when the method to widen largely the rope line distance is to be established in the future.

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We estimated total surface area of some Japanese coal by the volumetric gas adsorption method. From these results, the relations between pore size and surface area in coals were clarified. For the confirmation of the relations in question, we used the Kelvin equation that based on the capillary condensation theory.
Using the B.E.T. method, the surface areas of coals were derived from adsorption isotherms of nitrogen (at-196°C) and carbon dioxide (at-78°C).
The results obtained are as follows.
1) The surface areas determined with carbon dioxide, are greater than those with nitrogen.
2) If we give the physical and chemical reactivity of coal by means of the surface area and pore size distribution, one of the most responsible coal is Oshima.
3) The values of surface area do not always have definite connection with its pore size distribution. Namely, even if the coals have practically equal surface area, the pore size distribution of these coals are fairly different.

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The studies about hydraulic transport of solids by air lift pump are very few compared with studies about two phase flow of air and water.And, the results concerned with amount of air supplied (Qgo) and arnount of water lifted (Ql) are very different for the reason of differences of dimensions (pipe length L and pipe diameter D) in experimental apparatus or submergence ratio (σ).It was found by authors that the former works and authors' works could be rearranged uniformly using the dimensionless number f_L2(x) /σ^3/5 (where f_L2(x) was void fraction of water in pipe) and Froude number Frg (=Vgo/√2gL), and the relations above mentioned parameters were shownd as follows,
_??_
And the amount of water lifted and solids lifted (Ws) could be estimated by using the above mentioned relations and the functions of void fraction of water in three phase flow (f_L3(x)), concentration delivered (Cs) and ratio of diameter (d_s/D). The relations of above parameters were as follows,
_??_
And, also, the authors ascertained that the calculated values were agree with the experimental values of solids lifted by air lift pump.

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In the previous report it was shown that the structure of solid particles settled in water depends upon the bonding force at the contact point of particles and that the bulk density depends directly upon the mono-valent electrolyte concentration in system of SiO₂ particles and aqueous solution.
In the present report it is shown that the bulk density does not always depend on the poly-valent electrolyte concentration. It is impossible to explain smoothly these phonomenon without considering friction and adhesion. In this case adhesion refers to the resistant force in the vertical direction when the particles are separated in water. This force depends on the mutual action between Van der Waals attractive force and electric double layer.
Friction is resistant force in parallel direction when the particles are moved. This force depends on the boundary hydrated layer at solid-water interface.

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In order to examine the suitability of ferrous sulfides as a reductant of dichromate, the reduction characteristics of dichromate by ferrous sulfides in an acidic solution were investigated by doing the determination of reaction rate, the measurements of rest potential, and so on. The main results obtained are as follows:
(1) Both of the acid decomposition rate of ferrous sulfides and the reduction rate of dichromate by ferrous sulfides are influenced greatly by the stoichiometry of ferrous sulfides. Reaction with stoichiometric ferrous fulfide proceeds faster than that with iron-deficient ones.
(2) Sulfur species in the reacted products of non-oxidizing acid decomposition and of oxidation reaction of ferrous sulfide are affected by its stoichiometry. Sulfur in iron-deficient ferrous sulfides is oxidized more readily. From the differences in the reaction rate, reaction products and rest potential, we may propose the different meahnisms of oxidation reaction to the stoichiometric and non-stoichiometric ferrous sulfides.
(3) Oxidation reaction as well as non-oxidizing acid decomposition reaction of ferrous sulfides can be predicted by knowing their rest potential values.
(4) The reduction rate of dichromate solution with ferrous sulfides is accelerated by either increasing acid concentration, raising temperature or lowering rest potential. However, the efficient reduction of dichromate is associated with the evolution of hydrogen sulfide, suggesting that ferrous sulfide is not an attractive reductant of dichromate waste water.

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In the fundamental study on the non-ferrous pyrometallurgy, many experiments must be carried out under the conditions of the constant oxyten and the constant sulfur potentials, In such a case those potentials are controlled by using appropriate gas mixtures. The present study was undertaken in order to confirm the oxygen potentials of such gas mixtures by means of the following oxygen concentration cell,
O₂ (in gas mixture)/ ZrO₂+ (CaO)/O₂ (in air).
The oxygen potentials of gas mixture CO₂-SO₂-H₂-Ar were measured (1) for various initial mixing ratios of CO₂-H₂-SO₂ at constant Ar mole fraction of 0.5 and 1200°C, and (2) for various initial mixine ratios of CO₂-H₂, at contant Ar mole fraction of 0.5 and SO₂ moletraction of 0.005 and 1300°C. In each case the total pressure was kept 1 atm.
Also the theoretical oxygen potentials of such gas mixtures were calculated based on the material balance and the mass action law for the relating many chemical reactions, using the available data of free energies. In such calculation these gas mixtures were assumed to be ideal.
From the present experiment it was found that the oxygen potentials of the gas mixtures were in good agreement with the calculated values. Furthermore, based on such calculation, the oxygen and the sulfur potentials of different eight gas mixtures were estimated at 1300°C and these results were shown in Po₂vsPs₂ space.

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