Sidney Gilchrist Thomas (1850-1885), metallurgist and inventor
1850 April 16th. Thomas was born at Canonbury, London, son of William Thomas (1808 - 1867) and his wife Melicent. His father, a Welshman, was in the civil service, and his mother was the daughter of the Rev. James Gilchrist.
Educated at Dulwich College.
His father's death left his family with a considerably reduced income; Sidney gave up his original idea of becoming a doctor and obtained an appointment as a police court clerk, which he kept until May 1879.
1867 Teacher in an Essex school. Then clerk at Marlborough Street, police court
During these twelve years, besides the work of a busy police court, which brought him into intimate contact with social problems, he found time to study chemistry, and attended evening lectures at the Birkbeck Institute (which later became Birkbeck College).
c.1870 Started experiments on methods of removing phosphorus from the pig-iron used in the manufacture of steel in the Bessemer converter.
By the end of 1875 he was convinced that he had discovered a potential solution. He communicated the details to his cousin Percy Gilchrist, then chemist at the Blaenavon Ironworks, and experiments were made which proved satisfactory.
Edward Pritchard Martin, manager of the Blaenavon Works, gave facilities for conducting the experiments on a larger scale and undertook to help in taking out a patent.
In March 1878, the first public announcement of the discovery ‘that he had successfully dephosphorised iron in the Bessemer converter’ was made at the meeting of the Iron and Steel Institute. Took out a patent in May but without attracting much attention.
1878 Thomas announced at a meeting of the Iron and Steel Institute of Great Britain. This was put to use immediately with a large increase in steel production.
In September a paper was written by Thomas and Gilchrist on the "Elimination of Phosphorus in the Bessemer Converter" for the autumn meeting of the institute but was not read till May 1879.
Thomas made the acquaintance of Edward Windsor Richards, the manager of Bolckow, Vaughan and Co's works at Cleveland, whom he interested in the process, and from this time the success of the invention was assured and domestic and foreign patents were taken out.
The 'Basic process' invented by Thomas was especially valuable on the continent of Europe, where the proportion of phosphoric iron is much larger than in England, and both in Belgium and in Germany the name of the inventor became more widely known than in his own country. In America, although non-phosphoric iron largely predominated, an immense interest was taken in the invention. The improved process resulted in much more slag forming in the converter. Thomas discovered this 'Basic slag' could be useful and profitable as a phosphate fertiliser, which led to him becoming rich.
Thomas had been overworking for years, and his lungs became affected. A long sea voyage and a residence in Egypt proved unavailing to restore his health
1885 February 1st. Died in Paris and was buried at Passy
1885 Obituary 
SIDNEY GILCHRIST THOMAS was born in London in 1850, and was educated at Dulwich College, whence it was intended that he should proceed to London University with the view of graduating in arts, and ultimately following the medical profession. The death of his father frustrated this object, and, after acting for a short time as teacher in a private school, young Thomas, at the age of seventeen, entered the Civil Service, in which he remained till 1879. During this period he devoted much of his leisure time to scientific studies, chiefly metallurgical.
For a time he attended and received evening tuition at Mr. Vache's laboratory, and aimed at qualifying himself for passing the examinations at the School of Mines, although his other duties did not allow of his attending the lectures over the three years' curriculum. He succeeded, nevertheless, in passing all the examinations of that school, except that in metallurgy, which is only open to students that attend the whole course. It was while thus occupied that Mr. Thomas conceived the idea of using a strong base in order to eliminate phosphorus in the Bessemer process. Having provided himself with a miniature converter, he made many experiments designed to effect this end, using lime or magnesia for the lining of the vessel. He found, however, that he could not, in experiments carried out on such a small scale, obtain all the conditions necessary to the complete elucidation of the problem, and he especially failed in obtaining the necessary pressure of blast. At this juncture he secured the co-operation of Mr. P. C. Gilchrist, then chemist at the Blaenavon Works in South Wales, and of Mr. E. P. Martin, then the general manager of that establishment.
After more than a year of further experiments, carried on with crucibles and converters lined with different substances, Messrs. Thomas and Gilchrist succeeded, in 1877, in obtaining such results as to satisfy them that phosphorus could be eliminated in the Bessemer converter by the use of a basic lining. Having got Mr. Martin, on behalf of the Blaenavon Company, to erect a kiln in which they could burn the bricks necessary for their lime lining, one of their chief difficulties was removed, and by the assistance of this Company they were provided with a small converter in which their experiments could be effectually carried on.
Having secured their invention by patent, Messrs. Thomas and Gilchrist brought it under the notice of the late Mr. Menelaus, who gave facilities for making experiments in a 5-ton converter, which were not regarded as very encouraging, only five casts being obtained. It was, however, sufficiently established that dephosphorisation of the metal took place in the presence of the lime lining, and with this cardinal fact before them, Messrs. Thomas and Gilchrist prepared a paper in which they described the results that they had obtained up to the middle of 1878. This paper was submitted for the approval of the Council of the Iron and Steel Institute at the Paris meeting of that year, and was placed on the programme for reading on that occasion The time occupied by the papers that preceded it did not allow of this paper being read at Paris, and it was unavoidably held over until the next spring meeting of the Institute - not, as has been represented in some quarters, because the Council failed in any degree to appreciate its due importance, but simply because it was impossible to find time for its consideration.
Meanwhile, however, the subject had been brought under the notice of Mr. E. Windsor Richards, who, a few weeks after the Paris meeting, proceeded with Mr. Thomas to Blaenavon to witness for himself the operations which Mr. Thomas had described in his paper.
After seeing three blows in a miniature converter, Mr. Richards became satisfied that dephosphorisation of the metal actually took place. He thereupon made arrangements for putting the process to a test on a large scale. With this object two thirty-cwt. converters were erected at the works of Bolckow, Vaughan, & Co. at Middlesbrough. For a long time much difficulty was experienced in getting suitable bricks to line the converters, chiefly because of the "great shrinkage of the magnesian limestone when burnt in a kiln with an up-draught, and the failure of the ordinary bricks of the kiln to withstand the very high temperature necessary for efficient burning." These and other difficulties of a mechanical nature were ultimately so far got over as to allow of successful operations being shown to those interested at the Middlesbrough Works; and when, in the following May, the paper which had been held over from the Paris meeting under the circumstances already described was read at the London meeting of the Institute, Messrs. Thomas and Gilchrist were able to announce in unequivocal terms that the practical dephosphorisation of iron on a commercial scale was an accomplished fact.
The subsequent history of the basic Bessemer process can best be traced in the several papers read concerning it before the Institute by Mr. Thomas and others. The process was quickly taken up by different companies in Germany, Austria, France, Belgium, and Russia. In England, Messrs. Bolckow, Vaughan, & Co. at once made arrangements for carrying it on very extensively, and this firm was soon afterwards followed by the North-Eastern Steel Company, which had the benefit of the very valuable experience, gained at the cost of much anxiety, and patient and arduous labour, at the Cleveland Steel Works, and were enabled at once to lay down a plant which has since proved to be admirably adapted for its requirements. Other firms have followed the lead of the two mentioned, and the production of basic steel in this country, during the twelve months ending 30th September last, was upwards of 145,000 tons. Large, however, as this quantity is, it is much behind that produced on the Continent, where for the same period 748,000 tons of basic steel were manufactured, of which Germany and Austria produced 617,000 tons; France, 130,000 tons; and Belgium, &c., about 52,000 tons, giving a total make for the twelve months of 945,000 tons, or about 30 per cent. of the total make of Bessemer steel in Europe. There are now thirty-one different works employing the basic process, having a total of eighty-five converters. This success was not attained without great and unwearying exertions on the part of Mr. Thomas.
For several years after his first announcement of his practical solution of the phosphorus problem, labours were entailed upon him and successfully accomplished, which his never very robust constitution was but ill fitted to endure. He was continually being called upon to visit one or other of the many works that had resolved upon adopting his process, with the view of giving the benefit of his knowledge and experience in removing the chemical and mechanical drawbacks that are inevitably attendant upon a new departure of such importance and originality. Week after week, and month after month, were spent in steelworks at home and abroad, looking after the practical details of the process. Long journeys were undertaken in mid-winter, when his delicate frame should have been tenderly nurtured at home; and, worse than all, his entire disregard of creature comforts led him involuntarily to neglect even the most elementary necessities for the maintenance of his bodily strength.
Unfortunately it became apparent, only when too late, that the limited strength of Mr. Thomas had been seriously overtaxed, and his vital energies sadly impaired. He was advised to undertake a journey to the Antipodes, with the view of recuperation. The advice was acted on, and in 1881 he proceeded on a voyage to Australia. Taking the United States on his way, Mr. Thomas met with a cordial reception from the iron and steel manufacturers of that country. He eagerly availed himself of the facilities placed at his disposal on every side, visiting most of the principal places of note, and acquiring an intimate knowledge of both blast-furnace and steelworks practice. In Australia he made it his business to inquire into the resources of the several colonies for the manufacture of iron and steel, and wrote several important communications thereon to friends in England. The same unwearying thirst for knowledge led him to make an equally good use of his opportunities in India.
On his return to England, Mr. Thomas had acquired a fund of information relative to the requirements and resources of the countries that he had visited which, if he had been spared, would have been likely to bear fruit. But on his return journey he encountered severe weather in the Atlantic, which undid much of the benefit of his stay abroad. Much against his wishes and intentions, which had led him to cut out quite a different and a greatly more active programme, he was compelled again to seek in a foreign country for those aids to convalescence that were denied to him at home. He proceeded to Algiers, where he spent the greater part of 1883-84. During his absence the accounts received from him indicated the most sanguine hopes as to the future. He thought himself strong enough, in 1884, to venture as far as Paris, with a view to meeting some of his friends. There he was induced to remain until the winter was too far advanced to allow of his undertaking the risks of returning to Algiers, and, after many deceptive hopes of ultimate recovery, he died in that city on the 1st February 1885, in the thirty-fifth year of his age.
Although Mr. Thomas is best known, and will be chiefly remembered for his connection with the basic Bessemer process, he had established other and perhaps more lasting claims to live in the memories of those who knew him intimately. He was a man of varied attainments. Endowed with literary gifts and graces of a superior order, he had already done a good deal in the way of contributions to current literature, and had made not a few plans for doing much more. For some years he was a frequent contributor to one or more of our technical journals.
With the exception of the papers bearing upon his own process, Mr. Thomas did not contribute anything to the "Proceedings" of the Institute; nor did he even speak on any other subject, although he generally attended the meetings of the Institute between the date of his election to membership in 1878 and his decease. He had, however, conjointly with Mr. Gilchrist, read papers on the basic process before the Society of Arts, which awarded the authors thereof their gold medal.
In 1883 the Council of the Iron and Steel Institute resolved to recognise the value of the basic process by presenting to Mr. Snelus - who had discovered, some years before Mr. Thomas, the value of a lime lining and basic additions in the elimination of phosphorus - and to Mr. Thomas, two Bessemer gold medals. This was the first occasion on which the Council had ever awarded two medals at the same time or for the same process. In Mr. Thomas's absence, the medal of which he was the recipient was received on his behalf by Sir Henry Bessemer at the Middlesbrough meeting of the Institute.