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Sidney Gilchrist Thomas (Cadw)
‘These two young men, Thomas and Gilchrist of Blaenavon, did more for Britain's greatness than all the Kings and Queens put together.’
- Andrew Carnegie
A global hero of industry; in the 1870s, his experiments at Blaenavon Ironworks led to a boom in steel making that echoed around the world.
A clever chemist with steely determination

Sidney Gilchrist Thomas was always interested in science. Originally destined to be a doctor, after his father’s death he changed his plans. He became a police clerk, but his love of science led him to study chemistry and metallurgy in his spare time. During his studies, he learnt about the Bessemer Converter; a means of mass producing steel from iron. However, it had a flaw . Bessemer steel made from the most common type of ore was brittle as it had too much phosphorus. Sidney was told that “The man who eliminates phosphorus by means of the Bessemer Converter will make his fortune”. He was convinced he had the answer! He partnered up with his cousin Percy Carlyle Gilchrist, the work's chemist at Blaenavon Ironworks, where they conducted experiments in their own time. They developed a special lining for the converter which solved the problem. Steelworks in Europe and Russia hurried to use their invention, and the rich industrialist Andrew Carnegie quickly bought the rights to use it in America.

Sidney’s glory was short lived. He died aged just 35, as a result of lung damage caused by his experiments.

Sidney Gilchrist Thomas memorial at Blaenavon (Crown Copyright Visit Wales 2013)
Where to Visit?

Blaenavon Ironworks, where Sidney and his cousin carried out their pioneering experiments

Visit Blaenavon World Heritage Centre to find out what Blaenavon was like when Sidney lived here.

Dates
Birth: Blaenavon 16 April 1850
Death: 01 February 1885
Blaenavon Ironworks (Crown Copyright Visit Wales 2013)
Video Content
The Bessemer Converter!
Sidney Gilchrist Thomas
Ingenious Heroes