Sidney Gilchrist Thomas

In the mid-1870s the Blaenavon Ironworks chemist, Percy Gilchrist, and his cousin Sidney Gilchrist Thomas, carried out experiments at their own cost at Blaenavon, developing linings for Bessemer converters that would absorb the unwanted phosphorus.

Sidney Gilchrist Thomas announced the success of the experiments in London in March 1878, and in the subsequent scientific paper paid tribute to the assistance he and his cousin had received from the Blaenavon Company. By 1882 fourteen ironworks in Great Britain, France, Belgium, Germany, Russia and the Habsburg Empire had invested in converting to the Gilchrist-Thomas process.

Andrew Carnegie, the great American steelmaker paid 250,000 dollars for the right to use the process in the United States, and remarked that:

'These two young men, Thomas and Gilchrist of Blaenavon, did more for Britain's greatness than all the Kings and Queens put together. Moses struck the rock and brought forth water. They struck the useless phosphoric ore and transformed it into steel'.