born Dec. 27, 1851, Lyme Regis, Dorset, Eng.
died Dec. 16, 1935, England
British metallurgist.
In 1876–77, with his cousin Sidney Gilchrist Thomas (1850–85), he devised the basic Bessemer process of making steel in Bessemer converters from phosphorus-containing pig iron. In the Thomas-Gilchrist process, the lining used in the converter is basic rather than acidic, and it captures the acidic phosphorus oxides formed upon blowing air through molten iron made from the high-phosphorus iron ore prevalent in Europe. The process subsequently became widely used.