In general the Japanese coals are of Tertiary origin and highly rich in volatile matter and ash, Which usually produce a friable coke with a poroua fingery structure.
The methods of coal preparation were early well studied and adopted effectively in our coking practice, especially the mixing of coals.
For the blast furnace coke we use mixtures of high volatile native coals from Kyushu and Hokkaido and low or medium volatile coals from China and Saghalien at the ratio of 80-60 to 20-40, carbonizing them in Koppers, Kuroda, Semet Solvey by-product coke ovens. The stamping practice has lately been abandoned, but for the foundry purpose it makes a coke hard, being produced from high volatile coal often admixed with anthracitic coal and pitch. The fineness and the water content of charging coal largely affect the hardness of resulting coke in ours.
The narrow high coke oven and rapid coking are now under consideration, in connection with the variety of coal used. For the manufacture of blast furnace coke, he combustibility, reactivity, porosity, and strength of coke, their correlation, behavious in blast furnace must be studied.
As for the strength of coke only, it may control practically the result of blast furnace operation at some length.
The tumbling test or so-called drum test, which indicates both the resistance to impact and abrasion, seems to be most profitable for this purpose.
In by-product coke oven, the operating temperature is generally measured at about 1, 000°C-1, 100°C in oven chamber and 1, 100°C-1, 200°C (rarely 1, 300°C) in heating flue respectively.
Coke oven gas is utilized in heating of the own oven chamber, city use, steam raising plant, steel plant, roll mill, and etc.
As for the heating of coke oven, coke oven gas may be gradually superseded by the blast furnace gas or some other poor gases.
In this paper, the names of principal companies in Japan (including Manchuria), their historical development, the details of the ovens used, and the statistica of coke, gas, and by-products are summarized to show present position of the Japanese coke industry.

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It is not more than thirty years ago that the nation began manufacture of rolled steel. Not any rolled steel was produced in Japan until The Imperial Steel Works (Government owned) in Yawata began its operation in 1901, when the importation of rolled steel was about 200, 000 tons yearly.
Production of rolled steel in this country increased year by year, and the total production was about 1, 400, 000 tons in 1927; but the importation is still very large as totalled about 810, 000 tons in the same year.
Different kind of rolling mills working at present in Japan may be classified as the following.
(I) Mills for semi-finished products.
(I) Mills for semi-finished products.
a. Blooming mill.
b. Blooming mill followed by continuous billet and sheet bar mill.
c. Slabbing mill.
(II) Rail and structural mills.
a. Two-high reversing mill train.
b. Three-high mill train.
(III) Middle bar mills.
Three-high mill consisting of a train of three or four roll stands.
(IV) Small bar mills.
a. 310mm three-high or double two-high (Dowley's) finishing train consisting of three or four roll stands, preceede by one three high roughing stand of rolls of 400mm to 520mm diameter.
b. Combined 310mm two-high and 370mm three-high finishing mill with a common 440mm continuous roughing mill.
(V) Wire rod mills.
(a) Two-high finlshing mill of the Garret arrangement combined with a roughing mill train consisting of two roll stands, of rolls of 470mm dia., or continuous roughing mill of eight stands of rolls of 370mm diameter.
(VI) Plate mills.
a. Thick plate mill of three-high Lauth type, with rolls of 864mm diameter.
b. Thick plate, mill of two-high reversing type consisting of a train of one roughing and one finishing roll stand.
c. Middle plate mills. Three high Lauth type, with rolls of 680 to 760mm diameter. and
d. Two high pull-over type consisting of a train of one roughing and one finishing stand, capable to produce plate of 1mm to 3mm thick.
e. Universal plate mill. Three-high mill with rolls of 600mm and 480mm diameter and with a pair of vertical rolls of 460mm dia., capable to produce universal plate of 150 to 600mm wide.
(VII) Sheet mills.
a. Two-high pull over mill for sheet thinner than 1mm.
b. Tin plate mill.
Two-high pull-over mill for producing sheet for tinning.
In this paper different kinds of rolling mills in Japan are described, under above classih-cation, about their sizes, capacities, kinds of products, method of operations & c. Table I.
VII are the lists of these rolling mills.
Tube mills and tyre mills are not described in this paper, because these mills belong to special kinds.
Figures showing arrangements and operating conditions of typical rolling mills are also inserted in this paper.

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Metallic Magnesium reacts with chloride solution with such a speed as that of the dissolution of zinc in acids. An equivalent quantity of hydrogen is evolved and Cl-ion remains constant. The author investigated the chemical reaction between metallic magnesium and aqueous solutions containing various salts. Impurities of the metal, gases dissolved in the solution such as O₂, N₂, CO₂, and OH-ion caused no reaction. Among the anions, only Cl-ion showed an intense reaction, the others acted scarcely upon magnesium. Cl-ion participates directly and intimately in the reaction mechanism, but H+ ion seems to be indifferent. Factors involved in the reaction mechanism are, therefore, limited to Mg atom, water molecule and Cl-ion. Various theories and opinions ever proposed were discussed and all were found to be incorrect. The author's view at present is as follows:
Chemical reaction takes place between Mg atom, H₂O or (H₂O)₃ molecule and Cl-ion, expelling gaseous hydrogen and some intermediate compound is formed. In the next moment, decomposes this compound again precipitating Mg (OH)₂ and recovering Cl-ion. This ion causes again the same reaction, thus, acting as a kind of catalyser.

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