The pyrite, galena, chalcopyrite, zincblend (black jack), ruby zinc, marmatite, enargite, arsenopyrite, stibnite and molybdenite were used for samples of sulphide minerals and 3.5% NaCl solution was used as an average sea water.
The experiments of the flotation of various sulphide minerals in 3.5% NaCl solution of various H-ion concentration were carried out by applying given amounts of flotation agents, i.e. camphor white oil, K-ethyl xanthate and Kerosene.
From the results of the experiments, the author has arrived at the following conclusion:
1) The sea-water can be used for flotation and in general the floatability of sulphide minerals in sea-water is similar to that in distilled water.
2) The “natural froth” of flotation in sea-water, i.e. the froth without any addition of frothing agent, generally has no collecting power, but easily flotable sulphide minerals, e.g. stibnite and molybdenite are partly collected in the natural froth.
3) Maximum floatability of galena in sea-water lies in the pH range 5.1-10.6; that in distilled water in the wider range 1-11.
4) Floatability of energite is notably depressed in sea-water.

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The second chaper deals with the change and the effect of iron in leaching operation.
The experiments treated here are as follows:
(a) The leaching percent of iron and zinc in the cases of free acid of the definite concentrate in various temperatures, and of free acid of various concentrates in the definite temperature.
(b) By knowing how the loss of copper and zinc is caused by calcium hydroxide which is added, in the last process of leaching operation, for the purpose of precipitating iron, and by fixing the allowable quantity of calcium hydroxide, the loss of copper and zinc can be reduced to the minimum.
(c) In leaching of zinc ore containing antimon and arsenic, the removal of these two metals by iron hydroxide has been ascertained to be due to adsorption. Then, by fixing the right quantity of iron hydroxide needed for the quantity of antimon and arsenic contained, the most effectual method of operating zinc ore containing the metals can be explained.
Next the writer has made clear how in industrial working iron in roasted ore changes in neutral leaching and acid leaching, and how reducing action of zinc sulphide not oxidized in roasting operation can work upon ferrie sulphate.

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