Wear of the cylinder of the diesel engine is an important problem. The auther assured that quenching, chromium-plating and nitriding are most effective for its bearing. In this report the quenching conditions of cast iron experimentally determined and the quenched cylinders were driven. The results shows their wear-resistance becomes twice or three times as much as one of a common cylinder. The results of chromium-plating and nitriding will be found in the following report. (M. I.)

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  It was very difficult to directly measure the roughness of heavy castings up to this time. Without preparing for the test-piece specially, the ronghness of heavy castings can be measured by means of this method.
  1) After studying the plastic substances made from Gypsum and Urea-Resine, it was cleared its special qualities.
  2) Studying the method of reproducing the surface of castings, it was successfully discovered to make the strong plastic test piece used for the reproduction.

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  It was attempted that sintering ore could be used in stead of iron ore (limonite or hematite) for oreing because of iron ores lacking. This sintering ore is made of pyrite cinder or purple ore.
  Sintering ore was used oxidizing process of cast steel making in the basic electric furnace (capacity : 6 ton).
  Its result is favcurable and can stand comparison with iron ore. Moreover, sintering ore is superior at several points than limonite.
  From our studies, it can be co cluded that shown in followings.
 (1) Decarburizing velocity is about 0.005∼0.008 C % /min by using 10 Kg ore/T molten metal, and is a match for iron ore.
 (2) Sulpher and cupper contents of sintering ore are free out of plain carbon steel making. Particularly, we gain sulpher content below 0.015% by using sintering ore pyrite cinder and purple ore.
 (3) Sintering ore does not hold H₂O and much powder as limonite.
 (4) Sintering ore is cheaper price.

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  It is believed by many foundrymen that waste products increase at rainy season due to increase of hydrogen content of cast iron.
  The present uthor investigated the relation between percentage of waste products and humidity on every melting extending over a year in some foundries, and found that there is no definite relation between them.
  In labolatory, the auther repeated the process of melting and casting over 40 times under different conditions and analysed, each time, the evolved gases. Wet air or steam was blown upon the molton iron in different conditions. In few cases he detected H₂ of less than 1%, but generally he found no H₂ or CH₄ in the evolved gases.
  Thus the humidity of melting atmosphere does not increase H₂ at all and consequently can not be the cause of waste products. The influence of humidity upon the molding sand was not touched upon.

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