Apjohn, James (1796–1886), chemist and mineralogist, was born 1 September 1796 at Granard, Co. Limerick, son of Thomas Apjohn, tax collector, of Sunville House, Limerick. He attended Tipperary grammar school, and entered TCD (1813), where he won a scholarship (1815) and graduated (BA 1817, MB 1821); the degree of MD was awarded in 1837. His first researches in chemistry were published in 1821; in 1825 he was appointed lecturer in chemistry at the newly founded Parke St. private medical school. He was appointed professor of chemistry in 1826 at the Royal Cork Institution, and in 1828 at the Royal College of Surgeons in Ireland, where he taught until 1850. At TCD he held three chairs: those of applied chemistry (1844–81) and mineralogy (1845–81) in its school of engineering, and the university chair of chemistry (1850–75). He created a lasting reputation as a teacher and researcher. He was most interested in physical chemistry, especially in the specific heat of gases; ‘Apjohn's formula’ for calculating the dew point from observation of the wet-bulb hygrometer was published in the Transactions of the Royal Irish Academy (1835), and became widely known. The RIA's Cunningham medal was awarded him (1839) for work on ‘a new method of investigating gaseous bodies’, and he was elected FRS in 1853. Apjohn developed interests in mineralogy, where he analysed and described new minerals; one from South Africa was later named Apjohnite, and he also described Kilbrickenite from Co. Clare, and Jellettite, a garnet mineral, discovered by J. H. Jellett (qv) (later provost of TCD) in Switzerland. He performed other painstaking analyses of substances, including jade, and took on the responsibility of checking all the chemical processes and tests described in the first edition of the British Pharmacopoeia. He published a catalogue of Trinity's mineral collection in 1850 and a textbook, Manual of the metalloids (1864), which had two editions, but was superseded by rapid developments in inorganic chemistry. He was president of the Geological Society of Dublin (1841, 1842), and was at one time vice-president of the RIA. He represented TCD (1858–78) on the general medical council, and helped to found the City of Dublin Hospital, to which he became consulting physician, but made few contributions to medical literature except for a few articles in The cyclopaedia of practical medicine (1833–5). He married (date unknown) Anne White (1809–1902) of Kilmoylan, Co. Limerick, who was known as a collector of algae (and for whom William Henry Harvey (qv) named the genus Apjohnia). They had three or possibly four sons and two daughters, among them Richard (also a chemist). James Apjohn died in South Hill, Blackrock, Co. Dublin, on 2 June 1886, and is buried in Mount Jerome cemetery, Dublin. The collection of minerals catalogued by him in 1850 is in the Geological Museum, TCD.
British Medical Journal, i (1886), 1244; Anon., ‘James Apjohn’, Journal of the Chemical Society, li (1887), 469–70; Boase supp.; Poggendorff; Alumni Dubl.; Crone; R. G. W. Anderson, ‘James Apjohn, chemist and mineralogist 1796–1886’, R. C. Mollan and others (ed.), Some people and places in Irish science and technology (1990), 16–17; D. A. Webb, Trinity College Dublin record volume 1991 (1992), 116, 122