It is a well known fact that the addition of a very small amount of vanadium improves the quality of stcel, increasing its strength as well as ductility.
Unfortunately, however, the occurrence of this precious element in its available forms of compounds is very scarce, and can not satisfy metallurgical demands.
The price of Ferro-vanadium, consequently, is very high, so that it forms an almost insurmountable obstacle in the course of developing the manufacture of vanadium steel.
The magnetic sand in Japan, without exception, contains certain quantities of V₂O₅, which sometimes exceed 0·6% in the original ore with a high iron content. Though the physical condition of the existence of V₂O₅ in the magnetic sand has not yet been cleared, when we apply the magnetic separation for the dressing of magnetic sand, nearly. all the content of V₂O₅ enters into the concentrate, resulting in a higher percentage of V₂O₅ in it than in the original ore.
From an economical point of view, the utilization of this element in the concentrate (or in the ore) affords a splendid prospect in the refining of magnetic sand, giving a superior quality to the product.
The author carried out several researches for reducing the V₂O₅ in magnetic sand with an electric furnace.
Naturally, varying degrees of reduction of V₂O₅ into the iron from the sand might give remarkable variations on the quality of the product. as well as their composition, say, phosphorus, mangan, silicon, titan and carbon.
The results of the author's research are summarized as follows:-
(1). In the direct reduction of V₂O₅ from the fused mass in the electric furnace, the slag must have certain definite ratios of SiO₂ and CaO to reduce the V₂O₅ as perfectly as possible. In this case, the TiO₂ and Al₂O₃ are considered as neutrals, and the reduction of TiO₂ must be excluded as much as possible.
(2). For the above purpose, the slag should preferably have a composition approximating Bisilicate slag.
(3). The absorption of carbon by the iron produced at certain temperature depends on the basicity of the slag and the length of time held in the furnace.
(4). The vanadium content will accelerate the absorption of carbon in the iron produced.

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It is imperative that one should observe, how various defects in iron and steel occur while manufacturing or using them. The present writer, taking 15 cases, tested and explained in a metallographical and mechanical way. The causes of breaks or cracks, as they were observed, were mainly due to the poor chemical composition of the materials, the un-uniformity of its distribution, the crystalsegregation, the segregation of blowholes or slags. the incompetency of working or treating temperature, the un-uniform distribution of internal stress, the overworking, etc. Therefore, test should always be made of each individual case, considering the property and employment of each material.

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The purpose of the present investigation was to measure quantitatively the efficiency of a shield plate in resisting penetration by a rifle bullet. A simple, mechanical, and accurate method for determining the velocity of the bullet was devised, by which the velocity of the bullet after passing through test plates of different thickness was measured.
By this means the residual velocity vers. plate thickness curve for different metals was obtained.
This curve which is called the "characteristic curve" of the shielding efficiency of a metal was obtained for different metals and alloys. The curve not only dives the residual velocity of a bullet after passing throgh a shield plate of a given thickness, but also the thickness of the metal plate which is just sufficient to stop the impinging bullet, on the "penetration distance". The best material found as the result of the present investigation is a special steel, the penetration distance of which is 4·5mm. for a bullet 9 grams in mass and a velocity 790 meters per second.
The penetration distance of laminated plates, and of two plates of equal tbickness separated from each other by a distance was also measured. The same quantity for wood, sand and glass, of different kinds was also measured.

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