Henry Bessemer introduced the Bessemer process for inexpensive mass production of steel in 1856.
The process forced air through molten pig iron. Oxygen in the blast helped remove impurities, especially excess carbon, silicon, and manganese, while the heat from the chemical reactions kept the metal molten. This made it possible to produce large quantities of steel much more quickly and cheaply than older methods.
Bessemer announced the process at a meeting of the British Association for the Advancement of Science in Cheltenham in 1856. He later developed improved equipment and licensed the technology. The process transformed railways, construction, machinery, and weapons manufacturing during the nineteenth century.
William Kelly independently developed a related air-blowing method in the United States, so Bessemer was not the only person to investigate this approach. The Bessemer process also worked poorly with some ores containing phosphorus until later improvements, including the basic process, solved that problem.