The Bessemer process was the first inexpensive industrial process for the mass-production of steel from molten pig iron. The process is named after its inventor, Henry Bessemer, who took out a patent on the process in 1855. The key principle is the removal of impurities from the iron by oxidation with air being blown through the molten iron. Steel was produced in great quantities before Bessemer's invention, but its quality varied widely. The need to constructing large machines, and large structures, such as suspension bridges required high-quality steel, and it was only possible because of Bessemer's invention.
