James E. Thomas, mining metallurgist, became a member of the Chemical and Metallurgical Society of South Africa in 1898. He continued as a member after the Anglo-Boer War (1899-1902), when the society was renamed the Chemical, Metallurgical and Mining Society of South Africa. During the war he appears to have left the Witwatersrand, for in March 1902 one J.E. Thomas - presumably him - requested permission from the authorities of the newly founded Transvaal Colony to proceed from Grahamstown to Johannesburg. From 1908 he served on the council of the Chemical, Metallurgical and Mining Society of South Africa, and was elected joint vice-president for 1913/4 and president for 1915/6. Three papers that he read before the society dealt with "Some improvements in cyanide works clean-up appliances" (Journal, 1903/4, Vol. 4); "The use of bisulphate of sodium in the [cyanide] clean-up" (with G.W. Williams*; Journal, 1904/5, Vol. 5); and "Cyanide works clean-up practice" (Journal, 1906/7, Vol. 7).
Later Thomas was one of the authors of A text-book of Rand metallurgical practice (London, 1912) by R.S.G. Stokes* and others. In 1921 he bought a rock dump from New Boksburg Gold Mines, Ltd. He was survived by his wife, Edith Mary Thomas, born Van der Riet, two sons and two daughters.