The demand for non-ferrous metals have largely been increasing with the recent rapid growth of the Japanese economy, but most of them depend on imports from abroad. It is required that Japan should develop by itself the mineral deposits and explore new large scale mines in abroad in order to maintain the stability of supply of minerals and ensure the more progress of the Japanese economy in the future.
Most of these already known excellent mines, however, are controlled by the advanced nations like the U. K., the U. S and the like. For this, we shall have to explore the rest which may have unfavorable conditions in the undeveloped regions of inconvenient districts. Therefore, this kind of development of the mineral resources takes a great expense as well as a great risk. As it is much difficult for Japanese private mining companies to, pursue such a development by themselves, it is in need of the powerful policy of Government to promote mining.
Especially, most. of these mineral resources expected to be developed seem to be in the developing countries, and so some difficult problems such as nationalization of mines and the on-the-spot smelting and etc. have occurred being caused by the recent rise of nationalism. It is desirable on the one hand to have cooperative system by not only mining companies but consumers, financial circles and many other industries concerned with such a development, and, on the other hand, it is required to organize the multilateral cooperation associated with the other country as well as the joint venture of the supply countries. Especially for the developing countries, weneed the organic combination between the problems of mining development and economic cooperation. As far as the development of mineral resources are concerned, we should not only consider our convenience but, contribute to the economic development of the supply countries, which are generally the developing countries, by means of it, and we should bear in mind that, as a result, this will give Japan possibility to maintain the necessary mineral resources. This should be called “Development of resources on the basis of cooperation” or “Cooperative Development.” The development of these unknown mines owes much to the great activity of those with frontier spirit, excellent skills, and management ability as citizens of the world.
From this point of view, we heartily expect the best activity of the members of “The Mining & Metallurgical Institute of Japan.”.

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It is well known that when an explosive charge is detonated in a material, the radial cracks are produced and grow around the explosion by the hoop stress in the spherical stress wave. But, there are many unknown points which must be clarified in the growth mechanism and the properties of these radial cracks, therefore, in this paper, the behaviour of the crack propagation has been discussed through the observation of the surface of the crack produced in a polymethyl methacrylate plate by a detonator's attack. The main results obtained are as follows;
1. The radial crack caused by an explosion (See Fig.2) is not produced continuously from the surface of the explosion. The intense stress wave projected into the material by an explosion creates at first many nuclei of the crack, and then the cracks from the respective nucleus interlink with each other producing finally the continuous long radial cracks (See Fig.12, 14).
2. The relation between the number of the nucleus per unit area N and the distance from the inner surface of the borehole r in which an explosive is detonated is shown in Fig.15. In the case where the decoupling coefficient is 1.1, the maximum value of N which is about 2.5×10³ pieces/cm² appears at the distance of r≅1.0cm, in the case where the decoupling coefficient is 2. 0, the maximum value of N that is about 5×10³ pieces/cm², appears nearer to the inner surface of the borehole. Thus, the number of the nucleus produced near by the inner surface of the borehole is less in the case where the decoupling coefficient is 1.1 than in the case where the decoupling coefficient is 2.0. It may be considered that one of the reason why this phenomenon appeared is the increase in the ductility of the material caused by the temperature rise in the material due to the adiabatic compression accompanied with the propagation of an intense stress wave.

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The torque required for the operation of a drum pelletizer has been investigated on the dry granular materials, and with the aid of the angular momentum theory assuming the two dimmensional steady state, the following equation has been induced theoretically.
T=Gx
If uniform bulk density prevails.
T=πρBgR³lJ (1-J)[x_G1-x_G2/R]
With several samples, under the various conditions, has hcen torque measured. These data showed the following relations.
T=Ksinφ_iπρBgR³lJ (1-J)(1.00+A√Rω²/g-B·Rω²/g)
where, A, B, K are constant, and in the present experiments, A=1.35, B=1.15, K=0.938 were obtained. Therefore, power can be calculated as L=Tω.
Lastly, the authors pointed out the theoretical errors in prevailing formulas having reported on the power requirement to drive a rotary dryer and so on.

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The immiscibility gap in the system copper-silver-selenium at 1, 200°C was determined, and a new equilibrium diagram of this system between 600° and 1, 200°C was proposed. Moreover, the form of occurrence of silver and selenium in blister copper was studied. The results obtained are as follows.
(1) The distribution ratio of silver between liquid metallic phase and selenide phase is about 1.6 at very low silver content and increases to about 2.5 with increasing silver content.
(2) There are two reactions in the equilibrium system copper-silver-silver selenide-cuprous selenide.
L_2>(N) =L_2>(N) +Ag+α at 882°C
L=(Cu)+(Ag)+α at 770°C
(3) It is confirmed that cuprous selenide and silver are the phases of the most importance in blister copper containing a small amount of silver and selenium, and silver selenide is extremely unlikely to appear to an appreciable extent.

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