Joshua Buchanan was a Fellow of the (British) Chemical Society. Presumably he worked in South America for some time, for in 1893 he published a paper on "The extraction of nitrate of sodium and iodine in northern Chili" in the Journal of the Society of Chemical Industry (Vol. 12, pp. 128-130). By 1894 he was living in Johannesburg and in March that year was elected as the first honorary secretary and treasurer of the Chemical and Metallurgical Society of South Africa. He held these positions for one year only, and then served as a member of the society's council during 1895/6. His death (during the first half of 1899) was announced in the society's Proceedings.
Buchanan read two papers before the society, both during 1894. The first was a "Note on determination of gold in cyanide solutions" (Proceedings, Vol. 1, pp. 27-28). The second dealt with "Gold and silver extraction in South America" (Vol. 1, pp. 41-49).