Bernard de Coligny Marchand, analytical chemist, was the son of Reverend Bernard Petrus Jacobus Marchand and his wife Annabella Wilson, born Lockhart. He attended the Boys' High School at Rondebosch (now part of Cape Town), and passed the matriculation examination of the University of the Cape of Good Hope in 1902. Continuing his studies at Victoria College, Stellenbosch, he was awarded the degree Bachelor of Arts (BA) by the university in 1906. He then proceeded to Germany where he studied at the University of Halle from about 1908 to 1911, but was awarded the degree Doctor of Science (DSc) by the University of Edinburgh in 1912.
Upon his return to South Africa Marchand was appointed as assistant chemist in the Division of Chemistry of the Department of Agriculture in 1913 and stationed in Pretoria. He succeeded H.J. Vipond* as Chief of the division in 1917, for a period of four years. Later he was appointed as government analyst under the Sale of food and drugs and seed act and the Wine, spirits and vinegar act of 1925. In that year he was transferred to Cape Town, but a few years later was sent to Johannesburg to head the Government Chemical Laboratories. Subsequently he returned to Cape Town, where he remained.
Marchand was soon recognised as an authority on soil fertility, particularly on the physical properties of soils. His publications included a number of papers in the South African Journal of Science, among them the following: 'The determination of phosphoric oxide, particularly in fertilisers' (1918); 'On the volumetric determination of phosphoric oxide' (1920); 'The origin of black turf soils in the Transvaal' (1924); 'The composition of the fractions separated by mechanical analysis from some Transvaal soils' (with C.R. van der Merwe, 1925); 'Notes on some physical properties of soils' (1926); and 'The sticky point water of soils' (1930). Other papers by him appeared in the Journal of the South African Chemical Institute, the South African Journal of Industries, and publications of the Department of Agriculture. The latter included 5 articles on the physical properties and chemical analysis of soils. His work on the sticky point of soil-water mixtures led to contacts with agricultural research workers at Rothamstead, England, and in Ireland, and during the joint meeting of the British and South African Associations for the Advancement of Science held in South Africa in 1929 developed into cooperation in the investigation of common problems.
Marchand was elected a Fellow of the Royal Society of South Africa in 1926. He was a member of the South African Chemical Institute from 1924, served on its council for many years from 1925, and was its president for 1927/8. He became a member of the South African Association for the Advancement of Science in 1915 and served as president of Section B (which included chemistry) in 1925. His presidential address dealt with 'Soil formation and classification' (South African Journal of Science, 1925). He was elected a member of the association's council in 1922 and served as such on and off until his death.
In his spare time Marchand was active in the translation of old documents form the time of the South African Republic and was associated with Ethel and James Gray who wrote A history of the discovery of the Witwatersrand goldfields (1940). He was survived by his wife, Gertrude Ivy Marchand, and a daughter.