George Thomas Beilby was a British industrial chemist. After studying at the University of Edinburgh he joined the Oakbank Oil Company as a chemist where, with W. Young, he improved the process of oil shale distillation during the period 1869 to 1881. One of his early publications was a paper, with J.B. McArthur, "On waste gas from oil stills" (Journal of the Society of Chemical Industry, 1887). Much of his subsequent work was relevant to the industries developing in South Africa. In 1890 he directed his attention to the production of cyanides in order to meet the rising demand for it in gold recovery by means of the McArthur-Forrest process. The manufacturing method he devised was used until 1906 by the Cassel Gold Extraction Company (later the Cassel Cyanide Company), of which he became a director. He also studied the economic use of fuel, experimenting in 1906 with the low temperature carbonisation of coal and later studying the cell structure of coke. In 1917 he became the first chairman and director of the British Fuel Research Board.
Beilby also did significant research in Glasgow on the flow of solids, especially on the surface processes taking place when a metal surface is polished. His results were reported in more than a dozen papers from about 1903 onwards. He found that the crystalline structure of the metal is partly broken down, forming a non-crystalline surface layer with glass-like properties. In 1905 he published a comprehensive paper on "Gold in science and in industry" in the Annual Report of the Smithsonian Institution. That same year he visited southern Africa to attend the joint meeting of the British and South African Associations for the Advancement of Science, serving as president of Section B (chemistry). His presidential address on 29 August 1905 in Johannesburg dealt with his research on the metallurgy of gold and iron, particularly with their surface deformation and phase changes. He also discussed the theory of osmosis and dissociation in dilute solutions, with particular reference to gold solutions. In addition, he and Hubert N. Beilby of Glasgow (probably his son) read a joint paper in Cape Town on 17 August on "The influence of phase changes on the tenacity of ductile metals at the ordinary temperature and at the boiling-point of liquid air". Beilby's research in metallurgy led eventually to the publication of his book, Aggregation and flow of solids (London, 1921, 256p).
Beilby was president of the (British) Society of Chemical Industry in 1899, and of the Institute of Chemistry from 1909 to 1912. From 1916 to 1918 he was president of the Institute of Metals. He was elected a fellow of the Royal Society of London in 1906.