Andrews, Thomas (1813–85), doctor, physical chemist, and university administrator, was born 19 December 1813 at 3 Donegall Square, Belfast, eldest son of Thomas John Andrews, linen merchant, of the well known Andrews family of Comber, and Elizabeth Andrews (née Stevenson) of Scotland. He attended Belfast Academy and Belfast Academical Institution (BAI), went to Glasgow University aged 15 to study chemistry, and published his first scientific paper in 1829. He studied medicine at TCD (1830–34), and graduated MD from Edinburgh (1835). He visited the Continent several times and met the foremost chemists of his day, including Dumas in Paris; declined two professorships of chemistry in Dublin; and returned to Belfast (1835) to establish a very successful medical practice and become professor of chemistry in BAI, where for ten years he gave lectures and practical courses. In 1845 Andrews was appointed vice-president of the newly formed QCB and gave up both his connection with BAI and his medical work. When QCB opened (1849) he became first professor of chemistry, retiring in 1879. An important figure in the early history of the college, he helped to develop its independent and comparatively liberal character.
Working first on the heat of combination of chemical substances, Andrews became known for the unequalled accuracy of his results; he made most of his own apparatus. He solved the problem of the nature of ozone, discovered by Schönbein (1840): with P. G. Tait, Andrews discovered that it was an allotropic form of oxygen, and this enabled others to establish its correct formula and density. In a series of experiments (his most important scientific work) he varied the temperature of gases under intense pressure and was able to show the continuity between the gaseous and liquid states. His discovery that all gases have a critical temperature below which liquefaction becomes possible (1861) was particularly significant. Many later developments in science and technology, such as refrigeration and the use of oxygen in hospitals, are based on his work. Along with others, he found that the blood of cholera patients was deficient in water and salt, an observation that became important for treatment.
Besides fifty-one scientific papers, he wrote on such questions as temperance and university reform, suggesting (1870) that women be admitted to the queen's colleges on a very restricted basis; no action was taken. His The church in Ireland (1869) advocated disestablishment and redistribution of church property to benefit all the people. He was deeply involved in famine relief work in the 1840s, despite many other commitments.
He married (18 September 1842) Jane Hardie, daughter of Maj. Walker of the 42nd Highlanders. They had two sons and four daughters, including Elizabeth Andrews (1843–1929), who wrote on Ulster folklore, and Mary K. Andrews (below). Andrews was elected MRIA (1839) and FRS (1849), was Bakerian lecturer to the Royal Society (1869, 1876), and received honorary LLDs from Edinburgh (1871), Dublin (1873), and Glasgow (1877), and a D.Sc. from the Queen's University of Ireland (1879). He declined a knighthood (1880) and died in Belfast 25/6 November 1885.
His youngest daughter, Mary Katherine Andrews (1851/2–1914), geologist, was born 5 October 1851/2. She was actively involved in the Belfast Naturalists' Field Club, carried out geological fieldwork in Co. Antrim and Co. Down, and was especially interested in glacial erratics, glacial denudation, and igneous rocks. Her work towards determining the direction of local iceflows is still sometimes cited; she published several papers in the Proceedings of the Belfast Naturalists' Field Club, and one in Nature (1876). She died, unmarried, in Royat, Puy-de-Dôme, a notable volcanic area of France, on 14 August 1914.