As important factors showing the physical properties of a sand mold, the grain form, the size and the distribution of sand grain in a sand mold for casting had been appointed by many investigators. An another factor affects on these properties, however, figures indicating a condition of space between each sand grain should be appointed.
  From this reason, what kind of scala is to indicate the space size were investigated. The relation between a reduced diameter for this and a grain size of sand in our foundries an average grain size should be decided to know the space in this case. Utilizing the results obtained, in the case of pouring cast iron in sand mold, the limit that molten metal not to intrude into the space between sand grain of mold has also been examined. (N. T.)

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  The semi-permanent mold that far used in our country is a loam sand type, but the molding practice is quite complicated and much experience is needed to make sound mold. Addition to this the heat conductivity, resistance at high temperature is very poor.
  To improve the properties of semi-permanent mold, the molding materials must be studied which have not only better beat conductivity, resistance at high temperature but also longer durability and easer to mold.
  Graphite powder is one of the molding materials which satisfy above properties. And so in this first report we studied the nature of graphite base mold, using sodium silicate and bentonite as the binder.
  From the standpoint of the green and dried strength, dried shrinkage, heat conductivity and durability of the mold, the best result is obtained with the following composition :
          Bentonite・・・・・・・・・10%
          Na₂SiO₃・・・・・・・・・18% (30 Báume aq. soln.)
          Graphite Powder・・・・・Rem.

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  In the first report, as the one step of the studies on the evolved gases from the molten cast irons, an attempt was made to discover the nature of the gas which is given off from the electric arcfurnace cast iron when their temperature fall.
  In the experiment the spoon and cup sealed with molten lead was designed for the gas collecting arrangement. The cup is connected with a ruber tube at the end to a 100 C. C. gas collecting bottle. The gas was collected in the atmospheric pressure, and tested in an Orsat Lougue analysis apparatus containing four tubes.
  The analysis data of hydrogen extended over a wide range and its advance increased in the rate of waste products. All things considered, hydrogen had bad influence on the electric arcfurnace cast iron.
  Although this experiment is rather crude and incomplete, he author is confident that further investigation of the obtained phenomena will the of considerable value to the studies on the evolved gases.

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