Settling method (temporarily named) for determing the clay content in moulding sand was investigated and compared with the standard method.
  A) The settling method : Utilizing the difference of settling velocity in water, clay and sand grain are divided in two layers. The clay content is represented in volume percentage.
  B) The standard method : After boiled in 0.025% NaOH solution, the sand test sample is placed in a jar. Filling the jar with distilled water, the contents are well stirred and then clay is siphoned off. Clay is determined in percentage terms of the original sampl weight.
  I found that the settling method had a conversible relation with the standard method under the careful measurement.

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  The influence of phosphorus contents on the structure of spheroidal graphite cast iron shall be announced in this report.
  Synthesizing the influence, the followings can be said :
 1) Up to 2 per cent of the phosphorus content, phosphorus is nothing to do with presipitation of spheroidal graphite.
  When the phosphorus content is over this value, the form of graphite becomes almost spheroidal lump with uneven externals.
  But it gives no harm when the content is in the limit of practical usage.
 2) When phosphorus is added to high carbon and high silicon cast iron with over 2 per cent, lump graphite appears in the structure with no magnesium addition.
 3) There are a little difference between ordinary grey cast iron and spheroidal graphite cast iron in the amount and the distribution of steadite under the same pouring temperature and the cooling rate.
 4) When spheroidal graphite cast iron contains more than 0.4 per cent phosphorus, carbide-like band structure appears in steadite.
  The cast iron with this structure seems to have considerably good wear-resistance-property.
 5) With pearlite spheroidal graphite cast iron containing up to 1 per cent phosphorus content, hardness increase can not be observed as the increasing percentages of phosphorus.

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  When high strength cast iron containing low carbon and low silicon is produced by adding steel scrap, it is apt to has a direction in distribution of graphite, to develop dendritic austenites and then crystalize eutectic graphite or free cementite between them, or to cause blow holes.
  These become more remarkable due to more addition of steel scrap, and also to a kind of raw pig iron. Raw pig iron having a difficult tendency of graphitization generally has more remarkable these tendencies. Therefore, in order to produce high strength cast iron containing low carbon and -silicon, small amount of steel scrap is added to comparatively low carbon and -silicon pig iron. By being inoculated by small amount of calcium-siliside in a ladle even when much steel scrap is added to any raw pig iron, high strength cast iron has no above deffects and easily has higher mechanical properties ; tensile strength 30 kg⁄mm², transverse stress 2000 kg and deflection 45mm. (M. I.)

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