Henry Louis, British metallurgist and consulting engineer, studied at the Royal School of Mines, London, from 1873 and became an associate of the School (ARSM) in 1876. During the next twenty years he worked in various positions all over the world: In iron and steel works in Nova Scotia, Swansea, and near Edinburgh; gold mining in South America and West Africa; gold and diamond mining in South Africa; tin and gold mining in Thailand, the Malay Peninsula and the Far East; and coal and iron mining in various countries. In 1884 he was co-author with J.A. Phillips of A treatise on ore deposits.
By 1887 Louis was in the South African Republic (Transvaal), for in that year his "Note on the occurrence of bismutite in the Transvaal" was published in the Mineralogical Magazine. The next year he was in Barberton, where he was elected a member of the Barberton Scientific and Literary Society at its fourth monthly meeting on 24 September 1888. At this time he was already a Fellow of the Geological Society of London and of the (British) Institute of Chemistry. In April 1889 he read a paper on "Amalgams" before the Barberton society, dealing first with alloys of mercury in general and then more specifically with gold amalgams, with several references to his own experiments in this field. His paper was published in the society's Proceedings. In October that year he was still in Barberton, attending the society's twelfth meeting.
Louis was at some time awarded the degree Master of Arts (MA). He was a member of the (British) Institution of Civil Engineers, became a member of the British Association for the Advancement of Science in 1896, was president of various societies, attended many conferences in Europe, and served on British government commissions relating to mining. From 1896 to 1923 he was professor of mining at the Durham College of Science, Newcastle-upon-Tyne, while he also lectured in metallurgy at the University of Durham. The latter institution awarded him an honorary Doctor of Science (DSc) degree. In addition to numerous metallurgical and mineralogical papers from 1886 onwards he published several books, including A handbook of gold milling (1894), The dressing of minerals (1909), The iron ore resources of the United Kingdom (1910), The metallurgy of tin (1911), Mineral valuation (1924), and Mineral deposits (1934). One of his later papers, "The economics of metalliferous mining", with H.F. Marriott* as co-author, was published in the South African Journal of Industry in 1924.