Thomas Andrews FRS FRSE, chemist and physicist who does important work on phase transitions between gases and liquids, is born in Belfast on December 19, 1813. He is a longtime professor of chemistry at Queen’s University Belfast.

Andrews’ father is a linen merchant. He attends the Belfast Academy and the Royal Belfast Academical Institution, where at the latter of which he studies mathematics under James Thomson. In 1828 he goes to the University of Glasgow to study chemistry under Professor Thomas Thomson, then studies at Trinity College, Dublin, where he gains distinction in classics as well as in science. Finally, at University of Edinburgh in 1835, he is awarded a doctorate in medicine.

Andrews begins a successful medical practice in his native Belfast in 1835, also giving instruction in chemistry at the Academical Institution. In 1842, he marries Jane Hardie Walker (1818–1899). They have six children, including the geologist Mary Andrews. In 1845 he is appointed vice-president of the newly established Queen’s University Belfast, and professor of chemistry there. He holds these two offices until his retirement in 1879 at age 66.

Andrews first becomes known as a scientific investigator with his work on the heat developed in chemical actions, for which the Royal Society awards him a Royal Medal in 1844. Another important investigation, undertaken in collaboration with Peter Guthrie Tait, is devoted to ozone.

Andrews’ reputation mainly rests on his work with liquefaction of gases. In the 1860s he carries out a very complete inquiry into the gas laws, expressing the relations of pressure, temperature, and volume in carbon dioxide. In particular, he establishes the concepts of critical temperature and critical pressure, showing that a substance passes from vapor to liquid state without any breach of continuity.

In Andrews’ experiments on phase transitions, he shows that carbon dioxide may be carried from any of the states we usually call liquid to any of those we usually call gas, without losing homogeneity. The mathematical physicist Josiah Willard Gibbs cites these results in support of the Gibbs free energy equation. They also set off a race among researchers to liquify various other gases. In 1877-78 Louis Paul Cailletet is the first to liquefy oxygen.

Andrews dies in Belfast on November 26, 1885, and is buried in the Borough Cemetery in the city.