STEEL OF CEMENTATION.
Steel of cementation, or that made from superior bars or good soft iron, by the addi tion of the proper quantity of carbon, is the most uniform and best for all the require ments of the arts that has yet been produced, or is likely to be produced for some time to come, by any other process. It has already been superseded, however, by Bessemer steel for most common uses, in which fine steel is not a necessity.
The best steel can only be made from the best iron, whether by one process or another; but, in the process of cementation, superior charcoal iron must be used ex clusively in order to produce good steel; yet the best cast steel for tools and cutlery cannot be made even from superior charcoal bar unless produced from peculiar ores or mixed with the carburet of manganese.
The steel-manufacturers of England formerly imported all their bar iron from Sweden or Russia, but they subsequently found the iron of Ulverston, England, and of Madras, India, to be equal to the best Swedish Danemora iron, which sold freely at £36 per ton when other brands of good Swedish charcoal iron sold for £1.5 the ton.
The black magnetic oxide of iron generally forms the best bar iron for cementation, but only peculiar kinds of this ore produce naturally the rare qualities of the Dane mora iron. We find tins peculiar ore in several localities in the United States, but
always in the vicinity of limestone and always accompanied with a small percentage of manganese.
But in 1839, Mr. Josiah M. Heath, of England, obtained a patent for the use of man ganese in the production of steel. It was found that by the introduction of one per cent. or less of carburet of manganese into the melting-pot along with the broken bars of blister steel, a cast steel was obtained, after fusion, of a quality much superior to that manufactured from common charcoal iron without the manganese.
In 1843, 25,000 tons of steel were converted in England; and of that quantity not more than 2500 tons were made from the imported bar. At one time, 70,000 tons of foreign bar iron were annually imported into England for the manufacture of steel and other purposes, for which domestic iron is now almost exclusively used; but Mr. Heath's invention enabled the steel-makers of England to produce good common steel even from ordinary coke iron. This invention has also made the Bessemer process a practical in dustry.