The spontaneous polarization method of the electrical prospecting is the simplest and the most favourable method and up to this time in analysin the field data it is usually to use the negative center of the equipotential curves and to assume the position of the polarized orebody, but there exists no exact method to determine the depth, size and dip of the orebody except Mr. Walter Stern's paper.
The author checked the above paper and calculated theoretically the relation existing in the quantities of the potential curves and proposed another method to determine the depth, size and dip of tne polarized orebody from the field data which differs from Stern's methods slightly in detail.

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The most of the Japanese cupriferous pyrite contains small amount of cobalt, which had been discarded owing to the difficulties in treating such raw material of extremely low grade as cupriferous pyrite During the war the author had made a series of research works and devised a new process which made it possible to recover the metal more economically as follows:
1. Rosting of pyrite concentrate produced at the flotation plant.
(Some regulations should be made to the ordinary roasting operation in sulphuric acid plant.)
2. Water leaching of the above cinder to dissolve sulphates of cobalt in it, a little amount of copper, iron, zinc, and manganese also come into the leaching solution.
(at this stage, most part of iron is separated from cobalt.)
3. Precipitation of copper-plus-iron and cobalt successively from the leached solution, the latter is the rough concentrate of cobalt, to refine it.
4. Smelting cobalt precipitate into crude metal which results in eliminating manganese and zinc.
5. Elecrolytic refining of crude. cobalt eliminating copper and iron contained in the anode. The plant was designed as the followings;
(1) Roasting shall be operated in the extant sulphric acid plant.
(2) Leaching of the cinder shall be operated by continuous counter current system.
(3) Leached solution shall also be treated by continuous current system.
(4) Refining plant shall be on such a small amount to be able to treat a small amount of cobalt precipitated.
(5) Capacity shall be 300 tons of pyrite cinder per day. Operation was continued for two years until the surrender, producing about 7 tons of metallic cobalt in total.

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To study the effect of impurities usually usully contained in fouled cyanide solutions on the rate of dissolution of gold, determination of the rate of dissolution of gold in potassium cyanide solutions of various concentrations were made.
(1) Potassium ethyl-zanthate (0.0002-0.008%) has a retarding effect on the dissolution of gold. This detrimental action is remarkable when zanthate ions exist in the cyanide solution. Zanthate, in the amount usually found in flotation circuits, does not precipitate gold in a pregnant cyanide solution.
(2) The addition of potassium sulphide (0.0005-0.03%) is also detrimental to the dissolution of gold, and gives a fatal result with the increase in its amount. The addition of lead acetate not only converts the soluble sulphide to a sulphide of lead, whch is relatively innocurous, but also affects the rate of dissolution of gold in a manner characteristic to lead acetate.
(3) Potassium ferrocyanide (0.002-0.2%) accelerates the dissolution of gold with an increasing amouut of it. The author conjectures that the fact is due to the substitution between gold and iron ions in cyanide solution, as iron is electronegative to gold, and to the local circuits consequently introdued on the surface of gold. This fact was confirmed by separate experiments using gold-iron cell and by discuccing the existence of iron on the gold surface.
(4) Potassium zincocyanide (0.002-0.2% Zn) has little effect on the rate of dissolution of gold. It alone does not dissolve gold, but dissolves gold yielding potassium cyanide by the addition of free alkali. The rate of dissolution of gold increases steadily up to the rate corresponding to 0.03 per cent KCN.
(5) The double cyanide of copper and potassium (0.002-0.1% Cu) has also no effect on the rate of dissolution of gold.
(6) Potassium thiocyanate (0.02-0.2%) eliminates the passive state which should appear at the beginning in the dissolution of gold in pure cyanide solutions. This effect seems to be due to the fact that this cyanate alone dissolve gold at a very slow rate and consequently increases alkalinity of the solution.
(7) Potassium sulphate (0.02-1.0%) also ellminates the passive state at the beginning. Tue author conjectures that the fact is concerned with the decomposition of hydrogen peroxide.
(8) Some experiments, in the case of simultaneous addition of several impurities were made. The impurities, were classified by their characteristic behaviours. The effect of lead and iron salts is most remarkable and the following roder of intensity of action is obtained: K₂S, Ca (OH) ₂, K₂SO₄ and KCNS. Copper and zinc salts affect little the rate of dissolution of gold.

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