Having left Dulwich College, Sidney Gilchrist Thomas (1850-1885) was employed as a police-court clerk. Whilst working, Thomas attended lectures at Birkbeck College, University of London and there discovered a method for removing phosphorus from iron in a Besemer converter. This discovery made huge stores of phosphatic iron ore usable for steel manufacture. Thomas consequently resigned his job in the police force and spent his time administating the patent of his discovery. Thomas died in France at the age of 35.
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