John R. Williams, pioneer metallurgist on the Witwatersrand, received his training in Swansea, Wales, and became a member of the (Bitish) Institution of Mining and Metallurgy, the (British) Institute of Mining and Mechanical Engineers, and the American Institute of Mining Engineers. He came to the Cape Colony in 1881 and was employed by the Cape Copper Company in Namaqualand. In 1888 he moved to Johannesburg, where he conducted research on methods to improve gold recovery. In 1892 he first demonstrated that gold could be recovered economically from pyrite concentrates on a commercial scale on the Witwatersrand, at Langlaagte Estates. Later, in conjunction with others, he introduced the far cheaper method of hydraulic classification to effect concentration, a method that came into general use on the Rand. His outstanding achievement was the introduction of the first successful method of treating slimes (a suspension of very fine rock dust), thus improving the recovery of gold by the cyanide process. He was also responsible for the first tube mill working on the Witwatersrand, at the Glen Deep Mine. As an expert on the cyanide process he was a witness in the court case, heard in Johannesburg in 1896, relating to possible infringements of the McArthur-Forrest patent by Witwatersrand mines. Shortly after the Anglo-Boer War (1899-1902) he was consulting chemist and metallurgist to H. Eckstein & Co., Johannesburg.
Williams was a foundation member of the Chemical and Metallurgical Society of South Africa in 1894 and served on its council from 1895. He was president from 1899 to 1903, a period that included the Anglo-Boer War (1899-1902) and a change in the society's name to the Chemical, Metallurgical and Mining Society of South Africa. From then until his death in 1941 he was a member of council as a past president, and during most of this time took an active part in its deliberations. As a keen and lively debater he frequently made valuable contributions to the discussions of papers, and for some time edited the society's Journal. An early contribution by him to the Proceedings of the society consisted of extensive comments on the electric precipitation of gold (the so-called Siemens-Halske process) versus precipitation by zinc (November 1896, Vol. 1, pp. 296-315), with reference to an earlier paper by A. von Gernet*. Other papers by him dealt with "The Welsh process of copper smelting" (October 1895, Vol. 1, pp. 177-183); "The treatment of battery slimes" (July 1897, Vol. 2, pp. 92-98); "The indirect advantages of a slimes plant" (April 1899); and his presidential address on metallurgy on the Witwatersrand (July 1899, Vol. 2, pp. 726-730). He was also one of the contributors to La cyanuration au Transvaal (1900), a publication by J.G. Bousquet* and others, prepared for the International Congress of Mining and Metallurgy in France.
From 1900 to 1905 Williams was an examiner for the University of the Cape of Good Hope in the treatment of minerals. He was a foundation member of the South African Association for the Advancement of Science (1902), served on its council for some years, and was elected president of Section A (which included chemistry) for 1903/4. In 1903 the governor of the Transvaal Colony appointed him a member of the Technical Education Commission, which made recommendations on the development of higher education in the colony. He was survived by his wife, Annie Mary Bradley, but not by any children.