On the Marine Parade at Lyme Regis, Dorset stands a group of attractive thatched cottages that look out over Lyme Bay. It was here at Harville Cottage, the house of Thomas Clarke, a retired Master Mariner, that Percy Carlyle Gilchrist was born on 27 December, 1851. His mother Anne (nee Burrows) was from an upper class family and she and her barrister husband Alexander were of independent means sharing the same writing, scholarly and intellectual interests. Alex chose not to practice as a lawyer and instead he pursued his life-long ambition of becoming a writer. The early years of the marriage were nomadic ones, spent travelling the country in search of information for the book Alex was writing. Two years after Percy was born they made their first home in an old manor house in Guildford.

Three more children were born to the Gilchrists who by 1856 had settled in Cheyne Row, London, but in 1861 Percy contracted scarlet fever which, in those days, was a life-threatening disease. Through contact with his son, Alex also contracted the disease to which he succumbed. With four children to support, Anne continued with her writing while Percy attended Felsted School, Essex, where he displayed an interest in the sciences. From Felsted he studied at the Royal School of Mines, South Kensington where he became a Murchison Medallist and obtained his associateship of that school three years later. He also became a member of both the Institution of Civil Engineers and the Institution of Mechanical Engineers. In 1877 Percy married Norah Fitzmaurice, the daughter of Captain L N Fitzmaurice, RN, by whom he had a son Alexander, and a daughter Ellen.

Until the middle of the eighteenth century cast iron was the most common metal used in construction work but it contained a large number of impurities that made it brittle and liable to failure under stress. Removal of these impurities from the iron was a difficult process but when completed, it produced wrought iron that was softer and easier to work. However, both cast and wrought iron were prone to contain blowholes created during the casting process which made them unable to withstand strong tensile forces and it was this structural weakness that contributed to the disastrous failure of the Tay Bridge in 1879. By introducing carbon into the iron, steel could be created, a metal that was strong, flexible and durable, possessing all the qualities of cast and wrought iron but also capable of resisting high tensile forces. However, the process was difficult and expensive until Henry, later Sir Henry, Bessemer designed his converter.

Steel was produced in the Bessemer converter from impure pig iron smelted from the basic ores but sadly, it was not the perfect answer and frequently produced steel that was of poor quality and sometimes quite useless. The reason for this was eventually found to be the presence of the phosphorous that remained in the steel and which the converter had failed to remove. The most phosphorous-free ore in this country was the rich haematite discovered along the coast of Cumbria that led to the establishment of iron and steelworks in the region, the largest of which was at Barrow-in-Furness. But the deposits were limited and expensive to extract, consequently ore speculators moved to Spain where cheaper material was available.

After qualifying at the Royal School of Mines, Percy Gilchrist took up a post of analytical chemist at Cwm Avon Ironworks in South Wales and it was at this time that he was approached by his cousin Sydney Gilchrist Thomas, about a theory the latter had developed for eliminating phosphorous from Bessemer steel. Sydney Gilchrist Thomas who was about nine months older than his cousin, was a remarkable man. Due to financial difficulties following the early death of his father, he was forced to abandon his dream of studying medicine and instead, become a clerk in the Metropolitan Police Courts. But his real interest lay in chemistry which he studied with dedication in his spare time. While attending a course of lectures at the Birkbeck Institution he became fascinated in a particular lecture that referred to the scarcity of low phosphoric ores in the steel manufacturing industry. Mr George Chaloner, a lecturer in inorganic chemistry and metallurgy, stated that 'the man who succeeds in eliminating phosphorous in the Bessemer converter would one day make his fortune' and it was this remark that fired the imagination of the young Sydney Thomas. Thereafter he dedicated himself to the study of the problem that eventually led to the discovery of a process that became known as the Thomas-Gilchrist Process and for which he and his cousin Percy became famous.

In due course, Sydney Thomas also qualified as a chemist, but whilst still a clerk to the police court, he pursued his investigations by converting a room in his house into a makeshift laboratory where he undertook experimental work. However, the conditions were far from satisfactory and quite dangerous.
He was encouraged in his research by Chaloner at the Birkbeck Institution but being unable to carry out full-scale tests in a converter, Sydney wrote to his cousin explaining his theory and setting out the lines on which it could be tested.

Initially Percy Gilchrist was sceptical about his cousin's work and having just obtained a new post at the Blaenavon Works, he was reluctant to get involved in unofficial experiments. Consequently the experimental work was slow to start. But Sydney's enthusiasm gradually infected Percy and following a further meeting between the two, it was agreed that experimental work would commence, financed by Sydney Thomas out of his meagre salary. Gilchrist started the work in a rough shed on a mountainside but little was done until 1877 when the experiments began in earnest. As Gilchrist began to anticipate the success of the experiments the work advanced quite quickly, necessitating Sydney Thomas's more active co-operation; this required him to make frequent trips to Wales on the days he was off duty.

Similar work was proceeding without success on the continent and in America but the work that Percy Gilchrist was carrying out did not go unnoticed by E P Martin, the manager of the Blaenavon Works who became convinced that Gilchrist and Thomas were working on the right lines. He was so impressed with the results of their experiments that he arranged to relieve the cousins of their pressing financial worries by agreeing to buy shares in the patents for which they had applied, and to provide facilities for their research work to continue.

Details of Gilchrist and Thomas's work were presented for discussion at various meetings of learned institutions at home and overseas but their claims to have devised a process for successfully removing phosphorous from the Bessemer converter were met with scepticism and a certain amount of incredulity. However, a manager of a steelworks in Middlesbrough decided to pursue the matter and visited Blaenavon where he arranged for further tests that convinced him the dephosphorisation process was a commercial possibility. When the results of the successful tests became known Gilchrist and Thomas were besieged by steel manufacturers wishing to obtain the patent rights and their financial future was assured.

Sydney Thomas resigned his position at the police court and devoted himself to promoting the new process as well as negotiating patents and contracts with home and overseas manufacturers. New companies were formed of which the cousins were shareholders and Sydney travelled widely at home and abroad in connection with the work. Sadly he had never enjoyed good health and the strain of his early work, coupled with the extensive travelling soon took its toll. He spent the last few years of his life working on a project for converting the waste slag from the Bessemer converters with its high phosphate content into a basic fertilizer. He died, not yet thirty five years old, having made a fortune but not living to see basic slag become the highly valued fertilizer he had forecast.
Honours were bestowed on both men who were awarded the gold medal of the Society of Arts and the Bessemer Medal of the Iron and Steel Institute

Percy Gilchrist moved with his family to Redcar where he continued his work in the steel industry as the managing director of the Dephosphorising and Basic Patents Company Ltd., a company originally established to protect the rights of the process he and his cousin had developed. He was also associated with other companies in the steel industry.

The Thomas-Gilchrist process was taken up actively on the continent and was duly extended to the Siemens open-hearth process but for some reason, it gradually ceased to be employed in this country until its revival by a British firm in the mid-1930's. Percy Gilchrist may not have been aware of this for after along illness, he died on 15 December, 1935 some fifty years after his cousin with whom he had revolutionized the steel manufacturing process.

Since his death improvements have taken place in the process and although historically Gilchrist has been overshadowed by the figure of Thomas, there is no doubt that Percy's contribution to the invention of the basic process was just as great. He was the practical chemist and metallurgist who proved by experiment what his cousin had developed in theory. He was a member of the Iron and Steel Institute, of which he became Vice President, for sixty years and was elected a Fellow of the Royal Society in 1891, an honour that surely would have been bestowed also on his cousin had he lived.

An obelisk erected on the site of the Blaenavon Ironworks in Monmouthshire commemorates the experiments carried out by Gilchrist and Thomas and the Retired Chartered Engineers' Club, Exeter has fixed a plaque on the esplanade at Lyme Regis to record Gilchrist's birth in the town.

This chapter embraces the combined work of both Thomas and Gilchrist and shows that success also can be achieved by independent dedication and hard work. Today we have cranes that could lift the Eiffel Tower, buildings that soar 800 metres skywards and vessels of 500,000 tonnes travelling the oceans, all as a result of their pioneering work in developing the steel manufacturing process. Sydney Thomas had the dream that Percy Gilchrist made come true with the result that both men are equally revered in the annals of steel manufacture.

A G Banks