Reilly, Joseph (1889–1965), chemist, was born 3 September 1889 at 11 Creighton Street, Dublin, the son of Joseph Reilly, a policeman, from Longford, and Margaret Reilly (née Fulham), from Galway. His father died before Joseph's birth. Educated at the Christian Brothers’ School, Westland Row, and at St Mary's College, Rathmines, in 1908 he entered the Royal College of Science for Ireland (amalgamated with UCD in 1926) to study science. In 1911 he obtained an associateship in applied chemistry, having won first place in all examinations throughout his course. However, he did not immediately pursue a career as a research scientist, but instead completed a diploma in higher education at UCD (awarded 1912) while teaching at night in Kevin Street college of technology. Professor Gilbert Morgan, head of the chemistry department at his alma mater, then persuaded Reilly to take up research. He worked for two years with Morgan, and the results of this research, which had applications for arms and the war effort, appeared in six publications in the Proceedings of the Chemical Society. During this time he also published his first book, Aims and ideals in school science (1913), for which he was awarded an MA from UCD. Based on his research, Reilly won an 1851 exhibition scholarship which enabled him to travel to Cambridge, where he worked with Sir William Pope on the resolution of optically active nitrogen compounds (1914–15). His research with Pope and Morgan resulted in a D.Sc. from the NUI (1916) and fellowship of the College of Science at the age of twenty-seven.
During his research at Cambridge, Reilly became involved in the war effort and was appointed chemist-in-charge at the newly built laboratories of the Royal Navy cordite factory at Holton Heath, Dorset (1915–21). While there he published thirty papers on diverse subjects and discovered a new aromatic compound reaction, called the Reilly–Hickinbottom reaction. After the war he took a leave of absence (1919–20) to finish his scholarship and studied in Geneva with Professor Pictet on the thermal decomposition of sugars and celluloses; for this work he was awarded a D.Sc. By then a recognised explosives expert, Reilly moved back England to take up a position as deputy director of the explosives research branch of the Royal Arsenal at Woolwich (1921–3).
Having returned to Ireland in 1923, Reilly obtained an appointment as the assistant state chemist. A year later, on the retirement of Augustus Dixon, he was appointed to the chair of chemistry at UCC (1924–59), and he also served as dean of the faculty of science (1927–45). The initial focus of his research reflected the aspirations of the newly formed Irish government to develop the natural resources of the country. In applied chemistry he is best remembered for his research work on extracting polysaccharides and essential oils from Irish plants (reported in the Perfumery and Essential Oil Record), and latterly on useful derivatives from Irish peat (reported in the Proceedings of the Royal Dublin Society). In broader academic circles he was best known for his work on nitrogen compounds. During this time he published a textbook that was to make him famous, Physico-chemical methods (with W. N. Rae and S. T. Wheeler, first ed., 1926; fifth ed., 1954), for many years the standard work on practical physical chemistry. The book went to five editions over twenty-eight years, under the joint authorship first of Reilly and Rae, and eventually of Reilly as sole author. Throughout his career Reilly continued to publish in international journals, and also to run research projects in conjunction with international scientists. Other books written by him include Physico-chemical practical exercises (with W. N. Rae, 1934), Introduction to general practical chemistry (with Denis F. Kelly, 1940), Quantitative inorganic analysis (with Daniel G. O'Donovan, 1956), Oils from Irish-grown plants (1937), Complete book of vegetables and fruit (with G. O. Sherrard and F. Wrenne, 1946), and Vegetables and fruit: a nutritional survey (1947). He had a keen interest in the history of science, particularly chemistry in Ireland. With Margaret MacSweeny he published, in the Journal of the Cork Historical and Archaeological Society (lxii, lxiii, 1957), histories of the Royal Cork Institute and the Cork Cuverian Society. In all, he published over 200 papers and seven books. He was awarded the Boyle medal (1939) by the RDS and an honorary Sc.D. (TCD), was elected MRIA (1943), and was an active member of the RDS committee of Science for many years. He retired in 1959.
Regarded by colleagues as a versatile scientist, Reilly appeared formidable to those who did not know him well. To close acquaintances he was ‘Joss’, a gentle and charming person who was talented, witty, and understanding and had a wonderful way with children. Students found him encouraging and helpful. A keen bridge player and an able golfer, he also maintained an aviary of finches and related species when he lived in Blarney. The aviary was his pride and joy and was visited by ornithologists from many countries. His creative talents found expression in the Blarney Annual, a periodical founded by him, and in the compilation, editing, and publication of which he was involved up until his death. It featured short stories, articles, and anecdotes with an Irish flavour and enjoyed an extensive circulation in the south of Ireland. Reilly also contributed articles to the newspapers and during the 1939–45 Emergency encouraged the eating of wholemeal bread and mushrooms, as well as urging the extensive cultivation of oil-producing plants for the production of oils necessary for Irish industrial use. He married Chevaun O'Brien, the daughter of M. O'Brien, a medical doctor from Galway, with whom he had four sons and two daughters and a home at Glengorm, The Ridgeway, Bishopstown Avenue, Cork. He died 18 September 1965. A portrait of him by Mac Cana was commissioned for his retirement, and hangs in the chemistry department of UCC. In his honour the Reilly prize is awarded annually to a fourth-year student receiving first place and first-class honours in chemistry.