A low modulus instrument named hydraulic capsule for monitoring stress changes in rock is described with particular reference to itss ensitivity. Me thod to estimate the stressc hange in rock from the recorded pressure change has been proposed based on the two dimensional elasticm odel: Knowing the rock stiffnesas nd the length of the tubing, the pressurec hange can be easilyc onverted to the change of rock stressu sing Eq. 3 with an aid of two graphs as shown in Figs.9 and 10.
Its correctness has been verified in the laboratory study for several types of materials

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The development of high luminous safety cap lamps has been required in coal mines for a long time. But as the filament temperature of high luminous bulbs is higher than that of ordinary ones, high luminous bulbs have been considered to be unsuitable for use in coal mines.
Nevertheless, the authors consider, if high luminous bulbs were available, senior engineers or rescue crews would make use of them even though the usable time of batteries becomes short.
The authors-discussed the explosion-proofness of high luminous bulbs for safety cap lamps which were lighter compared with that of ordinary ones which were in everyday use in coal mines.
Experiments were carried out about explosion-proofness of high luminous safety cap lamps. Summary of the experimental results is as follows;
(1) It was confirmed that 1.4A-2 A bulbs of 2.5V rated voltage and 1A-2.5 A bulbs of 5V rated voltage were safe to methane-air mixture.
(2) As for the gases sealed in bulbs, krypton bulbs were about 20% lighter than argon bulbs under the condition that all these bulbs were of identical rated voltage and current.
(3) Compared with the argon bulbs of 2.5V-1.3A, the krypton bulbs of 2.5V-2A, 5V-1A and 5V 2.5A were respectively about 1.5, 3 and 3.7 times as bright as the argon bulbs.

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An abnormal dynamic tension on winding rope with a tail rope installed in rope guided winding shaft may be resulted from an emergency braking or a rough loading into the cage. This paper discusses the effectiveness of tail rope on such the dynamic tension of winding ropes. Some results obtained are as follows:
(1) Following on an emergency braking or a rough loading into the cage, the excursion of the acceleration value at the cage reaches almost twice of that value at the driving sheave.
(2) During emergency braking, ascending tail rope tends to float, by which the necessary grip on the driving sheave may be lost.
(3) When a load is dropped into the cage with zero head, the winding rope with no tail rope performs the 1st mode vibration. On winding rope with tail rope, the 2nd and 3rd mode vibrations are significant when the cage is nearby the pit mouth.
(4) At the cage depths where the tail rope is twice as long as the winding rope, the dynamic tension on the winding rope caused by a sudden loading is effectively reduced.
(5) A dynamic tension of 4-5 times greater than the loaded weight may appear at the driving end. when the load is dropped into the cage with a head of 0.1-0.2m.
(6) As the loading weight increases, the ratio of the peak value of dynamic tension to the loaded weight decreases.

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Acid drainage from iron sulfide mine is neutralized with calcium carbonate or calcium hydroxide errous ions to ferric ions. The precipitates formed, which mainly consist of ferric hydroxide and gypsu, mafter the oxidation off ailing dam. It is important to utilize these precipitates as iron and gypsum resources, are dumped to millt. Thus, the separation of ferric hydroxide from gypsum by flotation method has been investigated. It was shown that synthetic acid mine water containing 1000mg/l of ferric ions and 6000mg/l of sulfate ions was neutralized with calcium carbonate, and gypsum thus formed was selectively recovered in the froth using dodecylammonium acetate as a collector and soluble starch as a depressant for ferric hydroxide. It was also shown that soluble starch acted as a selective flocculant as well as a depressant for ferric hydroxide.
In the present paper, in order to find some effective organic depressants other than soluble starch for the flotation senara. tion of ferric hydroxide from gypsum, flotation tests were made at the same condition as above mentioned. And the effects of Several organic depressants such as tannin, gelatin, Na-carboxymethyl-cellose (C. M. C.) and soluble starch on the separation of ferric hydroxide from gypsum were investigated. As a result, soluble starch was found to be the most effective depressant tested, followed by gelatin, for ferric hydroxide. These two depressants markedly improved the selectivit. But tannin and C. M. C. were not so ettective.
Then, sedimentation tests were conducted for the suspension of ferric hydroxide and gypsum respectively, and the effects of above reagents used as depressant on the flocculation of the suspension were investigated. It was shown that each reagent did not flocculate gypsum but strongly flocculated ferric hydroxide and this result was thought to have some effects on flotation for separating these precipitates.
Also, flotation tests were made on the separation of ferric hydroxide from gypsum using some starches and starch products such as soluble starch, corn starch, potato starch and dextrin. It was found that soluble starch gave the best selectivity tested, followed by dextrin, potato starch and corn starch in the order named.

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In order to develop an appropriate method to accumulate numerically all of the distribution data, the digitization of the distribution data for divalent cobalt, copper, zinc and cadmium between hydrochloric acid solutions and the solutions of trioctylamine (TOA) in benzene has been examined by the methods utilizing chemical equilibrium model, its extended one and totally empirical one using a spline function.
Although the experimental data for solvent extraction of cobalt, copper, zinc and cadmium indicate that their distribution isotherms are of quite difference in shape each other, it is found that the method using a cubic spline function is most useful in them, in which the digitization is achieved by choosing the knots from experimental data appropriately with the aid of a microcomputer. By using the knots stored in memory, the numeric and graphic informations for the distribution of metals are obtained without any particular parameters. In contrast, it seems that chemical models are not always to follow the distribution data studied.

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