Abstract
The white cast irons which contain ca. 2·6% of C, ca. 1·15% of Si, various quantity of As and vqry minute quantity of other impurities were adopted as the specimens of the dilatometer.
The time required to complete the graphitization of the free cementite at constant temperature becomes somewhat longer as the As-content increases up to ca. 0·6%. The relation, however, is reversed when the As-content increascs over ca. 0·6%.
