Cast Iron

—A carbide of iron, contain in from 3 to 5% of carbon, both combined an as graphite, and about 24% of silicon This variety of iron, the production of th blast furnace, is valuable on account of th ease with which it can be melted and cas into moulds. It po e es great compre iv strength, 90,000 lbs. per square inch, but is wea in tension, breaking at about 18,000 Ibs., and i therefore used for building members in compres sion, and those parts of an engine, such as eylinde and bed plate, which are more easily cast to forr than manufactured in other ways.