By means of two apparatus made by the auther which one was used for measuring the flow of molding sand and the other was used for the cohesion of molding sand, the relations between the casting surface and the physical properties of molding sand (flow, cohesion and moldability) were researched. (Moldability which was called flowability by K. Kyle, was measured in accordance with the original device by Kyle.) The following are the results obtained;
  The sand Kawaguchi was used in this experiment. The casting metal was Lautal. The surface roughness of mold was measured by Light Cross Section Method, casting surface by Tracer Method.
  1) The more the moisture of molding sand, the lower the flow of it. The higher the flow of sand, the finer the mold-surface. On the occasion of the mold containing the extreme small moisture, defects are apt to occur on casting surface.
  2) The more the moisture of molding sand, the more the cohesion increases.
  The cohesion is, however, so small in case of the less content than 9% of moisture that the influence upon the surface roughness of mold and casting scarcely exists.
  3) There is a maximum value of moldability on the curve showing the relation between moldability and moisture content.
  In the extreme small content of moisture, moldability is generally poor. Under thi condition the flow of sand is high and the cohesion is small. Owing to this reason, the mold-surface was fine, but the casting-surface was apt to have the defects due to the low strength of mold.
  It is concluded that the best casting finish is obtained under the best moldability of sand.

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  With a view to welding the cast bronze liner of propeller shaft, the research on the electrode and its coating flux for bronze welding has been performed in our laboratories.
  Consequently it has been shown that an electrode containing 10 per cent. of tin, 4 per cent. of zinc and the rest of copper or 10 per cent. tin, 6 per cent. of zinc and the rest of copper, and also a flux consisting of Na₂SiO₃, 50 to 40 per cent.: Na₂CO₃, 30 to 20 per cent. and CaCO₃, 20 to 40 per cent. will give satisfactory results. Using these coated electrodes the welding of bronze liner were performed at the heating state on the joint of fitting propeller shaft into the trial cast bronze liner divided two parts with good testing results. Since these methods showed good physical and chemical properties, this type of welding operation is applied to commercial practice at present. (N.T.)

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  In the first report the author has investigated the size and distribution of clay particles produced in Kasuya (Fukuoka Prefecture) and Goto (Nagasaki Prefecture). In this report the authors has attempted to measure the permeability and bond strength of silica sand of uniform grain (60∼80 mesh) by addition of various grain size of clay particles and moisture. The clay particles are consisted of the silt part (10∼50μ), clay part (2∼10μ) and colloidal part (under 1μ).
  The result of investigation on the permeability of these moulding sand, it was found that the additin of moisture has an excellent effect up to 4∼6% for the separated fine clay content is constant, and the permeability is good in case of particle size is 5∼10μ.
  The bond strength does not shows any significant change by addition of clay particles up to 7%, even when the some moisture is exist, but if the amount of clay particles increases over 10%, the addition of moisture remarkably affects the bond strength.
  The proper amount of moisture has a close relationship with the fineness of clay particles and the amount of its effective range varies to the higher according to the finer clay particles. The maximum bond strength are obtained by adding the moisture up to 3% for 10% clay particles and the moisture 5% for 20% respectively.
  Finally, the addition of clay (2∼10μ) in moulding sand are recognized to improve permeability and bond strength. On the contrary the addition of silt (10∼50μ) does not influence any bonding power not withstanding it decreases permeability. These facts shows that the bonding power is not affected by the quantity of colloidal substance in the clay particles, but the main factor is depend upon the size and distribution of final clay particles.

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