People have produced iron and steel for thousands of years by heating iron ores and limestone with charcoal, anthracite coal, or coke to create a sturdy metal. Iron, whether hammered into shape as wrought iron or cast into molds, tends to be too brittle or too soft, but when its carbon content is reduced and various non-ferrous metals are added, it becomes steel. In the 1850s, English inventor Henry Bessemer pioneered an efficient method for converting raw pig iron into steel, and one of the earliest American companies to adopt this technology was in Bethlehem. From 1873 to 1896, Bethlehem Iron Company's double cruciform building housed Bessemer converters and rolling mills, where molten pig iron was poured into a pivoted converter, a blast of air was forced through the bottom to burn off almost all of the carbon, and the molten steel was then poured out after the oxidation process was complete.