Harry Rusden arrived on the Witwatersrand probably in or before 1899, for in that year he became an associate of the Chemical and Metallurgical Society of South Africa. He appears to have remained on the Witwatersrand during the Anglo-Boer War (1899-1902), for in 1902 he claimed compensation from the military government of the newly created Transvaal Colony. He remained an associate of the renamed Chemical, Metallurgical and Mining Society of South Africa and described his "Results of bag-house experiments in connection with Taverner's process" in the society's Journal (1904/5, Vol. 5). [P.S. Taverner's process, first introduced at the Bonanza mine in Johannesburg in August 1899, prevented the volatilisation of metallic zinc, with the consequent loss of gold, when smelting zinc-gold precipitate with litharge. In this process the precipitate, after filter-pressing (but without acid treatment or roasting), is mixed with litharge, slag, sand and sawdust, and smelted in a reverberatory furnace. The zinc is fluxed off without being volatilised to any appreciable extent]. Many years later Rusden and John M. Henderson* published a pamphlet titled The story of osmiridium on the Rand (Johannesburg, 1924, 4p). This naturally occurring alloy of (mainly) Osmium and Iridium was already being recovered regularly in the mines of the Witwatersrand at this time.
Before he came to South Africa, while still in Cornwall, Rusden was married to Nora Elizabeth Lidgey (died 1952), with whom he had a son and a daughter.