The author studied what amount of the sulphur would develop detrimental properties in practice. The result of the experiment was summarized as follows: (1) The running property of the melt becomes worse with increase of the sulphur, and especially worse when the sulphur is more than 0・282%. (2) When the sulphur reaches 0・282%, there appears a chill phenomenon, the shrinkage becomes maximum, and blow holes are found. (3) The combined carbon increases abruptly at 0・282% sulphur. (4) The graphitic

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... carbon becomes somewhat refined and the cementite more distinct at 0・282% sulphur. The grain size of manganese sulphide is maximum at 0・282% sulphur. (5) The tensile strength is enhanced with increase of the sulphur, but tends to be lower at around 0・282% sulphur. (6) The transverse load and the deflection shows a tendency similar to that of the tensile strength. (7) The hardness sharply rises at 0・282% sulphur.