i68 METALLURGY OF CAST IRON. chill or solidify it quickly, produce a fracture that will be close-grained in the one case and open in the other. This is just what the furnaceman does in making- sand cast pig iron. One part of his tap, or cast of iron, may run so slowly from his furnace as to " chill the metal," as it is called, before it reaches the pig; beds, while another tap or cast may come so fast as to fill the pig beds so rapidly, or make the pigs larger, that it will take much longer for the metal to solidify, and thus make the pigs more open grained than *k casts '' poured slower, or pouring smaller pigs. Again, one tap or cast at a furnace may give much hotter iron than another, and it is natural that the dull iron should cool faster than the hot, and, if both run at the same speed from the furnace down the long runners to the pig beds, the diiller metal will into one that willf charging, etc., to make excuses for his ill results, and not until such a paper as this, exposing the true cause of his trouble, might by chance fall into his hands is there any hope of his being made a follower of the new-school practice.