Generally, we detect or judge loose part. of rock by means of hearing the sound in the air originated by knocking the rock with hammer, but the results is not so reliable. The sound originated by knocking the rock with hammer would propagate in the air and rock.
This study is concentrated to clear the difference of these sounds according to the loose conditions of rock. There is little difference between the waveform of sound in the air originated by knocking the loose and crackless part of rock, but the waveform of sound in the rock has great difference according to the loose conditions of rock. Waveform of sound in the rock at the crackless part of rock is characterized by quickly weakening high frequency wave, i. e., 5, 000cps weakening its strength by 50% in 1/2, 000-1/3, 000sec. On the other hand, the sound in the rock at the loose part of rock contains the same high frequency wave as the case of the crackless part of rock in the very early part of the vibration wave, but it is followed by unique lower frequency wave, i. e., 10C-300cps decaying its strength rather slowly by 50% in 1/30-1/50sec.
In this regard, it can be said that the sound propagated in the rock is more dependable than that of in the air to make the practice of detecting loose part of rock more usefull.

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We have made researches on the vibration of winding ropes when they are braked in an emergency, picked-up while they are hanging freely, or accelerated by a periodical force on the ground of analytical results, which we have already gained in former studies (1st report).
Futhermore, we have investigated the effects of the shock absorber on the vibration, the influence of a tail rope or a head sheave on it and the decrease of vibration due to friction between cage and guide. We are going to give a few remarkable ones of the results we have obtained in our researches.
1) If the brake is conducted in a proper way, the vibration can be controlled and is not so large even if ropes are suddenly braked in an emergency.
2) When ropes hang freely are picked-up, or when ropes are accelerated by a periodical force, the vibration will become larger.
3) The shock absorber is considered to be effective only when a load is dropped into a cage.
4) There is no great error in regarding a tail rope as a weight, or a part of a cage.

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ガス抜きに対する長孔法の適用とガス抜き孔作孔について述べたが, これを要約すると次のとおりである。
(1) 水平長孔法を採用することによつて, 当鉱の切羽ガス抜きに対してparcyのRadialHowの式が適用される。
(2) 長孔法によるガス抜きは, 天盤貫層法や天盤坑道法に比較して, あらゆる点で有利である。
(3) 従来ガス抜きは経験によつて行われる面が多かつたが, 長孔法の採用によつて技術的な管理が行われるようになる。
(4) 長孔ガス抜き孔の急速作孔を目的として, 高推力でローラビットを使用する試錐機を製作した。これで1方当り40～50mの作孔速度が得られた。ビットの寿命は200～250rnである。
(5) 孔曲りを防ぐことは困難であるが, 孔曲りの測定によつて適当な作孔角度を見出し, 孔曲りを実用限界内におさめることが出来る。

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The author separated many kinds of pyrrhotite in Japan by Franz isodynamic separator, and studied some magnetic characteristics of them. The main results are as follows:
1) From the magnetic distribution curve obtained by isodynamic separation, two types are found. One is strongly magnetic of mono-peak type, and the other is weakly magnetic of di-peak type.
2) It is shown by the results of isodynamic separation on the samples from two deposits at Akagane mine, that one gives mono-peak curve, and the other gives di-peak curve. It is also considered that magnetic distribution on the samples from the same deposit have similar tendencies.
3) Most of the mono-peak type pyrrhotite are found in fissure filling deposit and most of di-peak ones occurr in metasomatic deposit. It means that magnetic property of pyrrhotite relates to its crystallization temperature.
4) As regard to thermo-magnetic curve of pyrrhotite, three types are found. One is of Weiss type, the second is of the peak type having a peak at 220-230°C, and the third is of the flat type which is independent of temperature.
5) The thermo-remanent magnetism of pyrrhotite is very strong, i. e. ten cr twenty times stronger than its natural magnetism.
Using the above character, weakly magnetic pyrrhotite can be recovered 90% by magnetic separation (800 Gauss) after it was heated at 300°C for half an hour.

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In cyaniding gold ores, Ca-cyanide is used instead of Na-cyanide, because the former is cheaper thanthe latter. But this reagent contains such impurities as sulfer compounds, Ca-compounds, and Na-chloride. Concerning the effects of these impurities, a fundamental reserach was performed by using gold plate and silver one respectively. The silver plate dissolved easily, and the gold one became gradually insoluble with the progress of time in the desulfurized Ca-cyanide solution. Then, using Na-carbonate, we tried to remove the Ca-compounds from the Ca-cyanide solution. These reactions are as follows:
Ca (CN) ₂+Na₂CO₃→CaCO₃+2NaCN Ca (OH) ₂+Na₂CO₃→CaCO₃+ 2NaOH CaS+ Na₂CO₃→CaCO₃+ Na₂S
The cyanide solution composed by the above treatment contains Na-cyanide and Na-chloride. For example, the concentration of Na-chloride in the 0.1% composed cyanide solution was about 0.08%. This composed cyanide solution dissolved much more gold than the ordinary Ca-cyanide solution. The decomposition pct. of cyanide in both of them was almost the same. The Na-chloride added to the ordinary Na-cyanide solution accelerated a little the dissolution of gold plate, while it decreased fairly that of silver plate.

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This paper is concerned with the kinetic study on the precipitation of UO₂ from various carbonates solutions in the presence of Ni powder by hydrogen pressure reduction.
The testing solutions are four different uranyl carbonate solutions prepared by the dissolution of refined UO₃ in K₂CO₃, Na₂CO₃ (NH₄) ₂CO₃ and ethylenediamine carbonate (EDA-CO₃).Experiments have been done in 2l stainless autoclave, equipped with the sampling device and the magnetic induction agitation system.
The results obtained are as follows:
(1) The precipitation rate of UO₂ from these carbonates solutions varies with cation species. It increases in order of K, Na, NH₄, and EDA.
(2) The activation energies from these carbonates solutions are 11.4, 14.1, 18.3 and 19.0kcal/mol respectively.
(3) There is a correlation between the precipitation rate and the hydrogen solubilities in various carbonates solutions.
(4) The precipitation rate increases in proportion to the amount of Ni powder.
(5) The concentration of carbonates influences the precipitation rate. In (NH₄) ₂CO₃ solution, the rate is in converse proportion to the square of its concentration.
(6) The precipitation rates increases in proportion to the square root of hydrogen partial pressures.
(7) From above results, the following rate formula is obtained. -d[U]/dt=K·S·P_H21/2·[M₂CO₃]-ⁿ·exp (-E_M/RT)

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静電選鉱は近年著しい発達を遂げ, その応用分野も相当広範囲に亘りつつある。米国のCarpco社はこの領域における主導的なメーカーとして, かなり古くから知られているが, 最近では鉄鉱石の選鉱に, 静電選鉱を大規模に適用することに成功し, 斯界の注目を集めている。ここに掲載した資料は, Carpco社の技師長W. P. DYRENFORTH氏が1957年10月, フロリダ州Tampaで開催されたAIME年次大会に発表した論文“Electrical Concentration of Iron Ore”を記述したもので, 本会選鉱専門委員三野英彦氏 (三井金属鉱業中央研究所次長2東京大学講師) が, 1960年5月, Carpco社を訪問の際, その別刷を同氏から贈られたものである。内容は従来の静電選鉱に対するわれわれの認識を改めさせるに足るもので, 関係各位の御参考になる点も多々あることと思い, 掲載させて頂くことにした。ここに誌上をかりて, 原論丈を提供された三野英彦氏に対し, 深く謝意を表する次第である。

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