Robert Mushet

Robert Mushet made the Bessemer process work, invented the first commercial tool steel, and died on a pension paid privately by the man who took the credit. Henry Bessemer announced in 1856 a method of making steel by blowing air through molten iron, and it failed in practice: the blast removed the carbon but also left the metal full of dissolved oxygen, so the product was brittle and unusable, and the licensees gave it up. Mushet, working in the Forest of Dean, found that adding spiegeleisen - an iron-manganese-carbon alloy - after the blow deoxidised the metal and restored the carbon to a controlled level. That step is what made bulk steel possible, and with it the rails, ships and structures of the second half of the century. He failed to pay a patent renewal fee in 1859, the patent lapsed, and Bessemer used the method freely; the accounts differ on whether the lapse was poverty, illness or an agent's error. Mushet also developed in 1868 a tungsten-manganese alloy that hardened in air rather than needing quenching, sold as Mushet's Special Steel, which cut metal at speeds ordinary tools could not survive and is the ancestor of modern high-speed steel. He was near destitute in the 1860s, and his daughter travelled to London to confront Bessemer, who thereafter paid him three hundred pounds a year for the rest of his life without ever conceding the point in public. Bessemer's autobiography acknowledges the debt obliquely. The process kept Bessemer's name. His father David Mushet was also an ironmaster and wrote extensively on metallurgy. Robert took out about forty patents and profited from almost none of them. A trail in the Forest of Dean carries his name.

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