Steel is not found native, but is a compound of iron and carbon and is produced artificially. The great value of steel lies in the fact that it can be made so hard that it can cut and shape almost every other substance known to man, and yet this very quality of hardness can be so modified as to make the metal capable of cutting and otherwise shaping itself. Steel can be made nearly as hard as the diamond, or so soft that it can be cut, bent, or hammered into this shape or that, rolled into sheets, or drawn out into the finest wire. Nearly the whole of the compound is iron, the carbon ranging from one-fourth of one per cent to two and one half per cent. Ordinary steel contains certain other chemicals, such as silicon, manganese, sulphur, and phosphorus, but these are mere natural impurities existing in the metal. The essential ingredients are iron and carbon. Steel is hardened by being heated to a high temperature and then suddenly cooled by contact with cold water, or in other like ways. Fixing the degree of hardness in a piece of steel is called tempering. The degree of hardness is dependent upon the suddenness of cooling.
The widespread use of steel and its importance in the life of to-day are due to Sir Henry Bessemer, an English inventor, who was born January 19, 1813, and died March 15, 1898. The substance was known, made, and used before the time of Bessemer, but its production was so costly that it was little used. By his process of production the cost was greatly reduced and steel consequently came into much wider usage. By the Bessemer process molten iron is poured into a vessel with holes in the bottom. Air at a powerful pressure is forced through these openings, so that the pressure of the air prevents the melted metal from running out. The air removes the carbon from the molten iron. Afterward the required amount of carbon is admitted to the iron, and the result of the union is a piece of steel. The process of Bessemer was patented in 1856.
Steel is used in the construction of great modern buildings, bridges, and battleships; and in making cannon, railroad cars and rails, pipe, wire, bolts and nails, swords, knives, saws, watch-springs, needles, and innumerable tools and articles of every-day usage. Manifestly a material that is used in the manufacture of articles ranging from a needle to a great city sky-scraper or a battleship must be of prime importance to the human race.
