Robert Forester Mushet (1811–1891), an English metallurgist,
1811 April 8th. Born at Coleford, Gloucestershire. He was the youngest son of Agnes Wilson and David Mushet, an ironmaster.
Robert spent his formative years studying metallurgy with his father, formerly of the Clyde, Alfreton and Whitclift Ironworks.
In 1856 Mushet found an inexpensive way to make high quality steel by adding ferro-manganese, or spiegeleisen brought from Rhennish Prussia. He explained that "during the summer of 1848 Mr. Henry Burgess, editor of The Bankers' Circular, brought me a lump of white crystallized metal which he said was found in Rhenish Prussia, where, he was told, a mountain of it existed. He had merely confounded iron with iron ore, an error often committed. Being familiar with alloys of iron and manganese," says Mr. Mushet, "I at once recognized this lump of metal as an alloy of these two metals and, as such, of great value in the making of steel. Later, I found that the white metallic alloy was the product of steel ore, called also spathose iron ore, being, in fact, a double carbonate of iron and manganese found in the Rhenish mountains, and that it was most carefully selected and smelted in small blast furnaces, charcoal fuel alone being employed and the only flux used being lime. The metal was run from the furnace into shallow iron troughs similar to the old refiners' boxes, and the cakes thus formed, when cold and broken up, showed large and beautifully bright facets and crystals specked with minute spots of uncombined carbon. It was called, from its brightness, 'spiegel glanz' or spiegel eisen, i.e., looking-glass iron. Practically its analysis was: Iron, 86…25; manganese, 8…50; and carbon, 5…25; making a total of 100…00."
This improved the steel's malleability – its ability to withstand rolling and forging at high temperatures – without which the Bessemer process for making steel would not have been an economic success. Bessemer's method had only produced "burnt" wrought iron, lacking strength, but Mushet's innovation restored the quality of the steel.
1857 Mushet was the first to make durable rails of steel rather than cast iron, providing the basis for the development of rail transportation throughout the world in the late Nineteenth century. The first of Mushet's steel rails was delivered to Derby Railway Station, where it was laid down early in 1857 at a heavily trafficked part of the line where the iron rails had to be renewed every six months, and occasionally every three." Six years later, in 1863, the rail seemed as perfect as ever, although some 700 trains had passed over it daily.
1857 In a second key advance in metallurgy, under a patent he applied for in 1857, Mushet produced the first commercial steel alloy in 1868 by adding a small amount (8%) of tungsten to the molten steel in the crucible. The steel hardened in the air, whereas previously the only way to make steel hard enough for machine tools had been to quench it, by rapid cooling in water. Self-hardening (or tungsten) steel machine tools could run much faster and were able to cut harder metals than had been possible previously. This resulted in a revolution in the design of machine tools and in the progress of industrial metalworking. High strength tool steels could be precision machined for the production of rifles, cutlery, surgical and other instruments.
Although Mushet filed many valid patents for his inventions, unreliable business partners allowed them to lapse. Mushet was rescued from insolvency and supported by Henry Bessemer, who had benefited by the free use of Mushet's lapsed patents.
1865 During the year there is a mass of correspondence from Robert Mushet on the Bessemer process in 'The Engineer'
Mushet died January 19, 1891 in Cheltenham.
1891 Obituary