New York Paper - Silicon in Cast-Iron (Analytical Determinations by H. S. FLEMING and EDWARD ORTON, JR.)

Cast-iron, or pig-iron, is iron which contains all the carbon that it could absorb during its reduction in the blast-furnace. As is well-known to chemists, carbon exists in cast-iron in two distinct forms. In chemical union, as "combined" carbon, it cannot be discerned, except as it may increase the whiteness of the fracture, in so-called white iron, or carburetted iron (sp. gr. about 7.72). Carbon mechanically mixed with the iron as graphite is visible, varying in color from gray to black, while the fracture of the iron, according to the color and amount of graphite it contains, ranges from a light to a very dark gray. The specific gravity of graphitic iron is about 7.40. Silicon in cast-iron is evidently to some extent combined with the iron and the carbon ; but whether it exists also in a form corresponding with graphitic carbon, mechanically mixed with the remaining mass, is a question still in dispute, which we have not in this paper endeavored to answer. It has been the opinion of many writers on metallurgy, and many foundry men, that silicon is in every way injurious to cast-iron. Yet