I2O METALLURGY OF CAST IRON.
'f bull ladle. *' We have made very good castings by this plan. We have also taken '' direct metal'' in crane ladles by having a car run on a track sunk sufficiently below the main runner to receive the metal from a branch runner extending beyond the casting house. With iron containing silicon under i.oo, manganese up to r .00, the higher the better, and sulphur above .03, it is rare that any kish is seen, and when such direct metal can be obtained very good castings can be produced. Of course, with a low silicon and high sulphur iron it is not to be expected that any work less than half an inch thick, requiring any fine finishing in the machine shop, can be satisfactorily obtained, but for bodies over the above thickness very little trouble should be experienced, as long as the metal does not get over one per cent, in silicon and keeps up in manganese and sulphur. As seen by study of Chapter XVII., it is the changeable percentages of silicon and sulphur which, as a rule, alter the grade in the product of a furnace when running on one kind of ore, flux, and fuel. Late improvements and a better understanding of furnace work is doing much to lessen irregularity in the percentages of silicon and sulphur. In fact, some furnaeemen have so mastered the art of making iron that they can run weeks at a time without varying 30 per cent, in silicon or three points in sulphur, when making iron having less than 1.25 silicon. It is with silicon above 1.50 per cent. also in very hot weather, as shown by Chapter XVII. --that the greatest difficulty is experienced, at present, in regularly obtaining a uniform grade of pig metal.main runner as it flows to the pigs and pouring it into aourtesy of Mr. Edgar S. Cook, president of the Warwick Iron Co. of Pottstown, Pa. is often surprising how rapidly, as about 75 per cent of the heat generated from the solid fuel is utilized. This is attained where one ton of coke will produce one ton of iron; and Sir........................ 2,720 "