An American, William Kelly, had held a patent for "a system of air blowing the carbon out of pig iron" a method of steel production known as the pneumatic process of steelmaking. Air is blown through molten pig iron to oxidize and remove unwanted impurities.

Bankruptcy forced Kelly to sell his patent to Bessemer, who had been working on a similar process for making steel. Bessemer patented "a decarbonization process, utilizing a blast of air" in 1855.

Modern steel is made using technology based on Bessemer's process. Bessemer was knighted in 1879 for his contribution to science. The "Bessemer Process" for mass-producing steel, was named after Bessemer.