Scientist. Born in Crieff, Thomson was educated at the Universities of St. Andrews and Edinburgh, graduating from the latter in medicine in 1799. While at Edinburgh he was taught by Professor Joseph Black (1728 - 1799) in the study of chemistry, and it was in that field which he was to make his mark. He visited Sweden in 1811 and then moved to London, where he edited the scientific journal Annals of Philosophy. He worked as a teacher and wrote articles on chemistry and related subjects for the Encyclopaedia Britannica, succeeding his elder brother, James (1768 - 1855) as a sub-editor from 1796 - 1800. In 1802, he published his noted System of Chemistry, which ran to numerous editions and went on to include the first detailed account of the atomic theory. He was elected a Fellow of the Royal Society of Edinburgh in 1805 and, in 1808, he founded the Wernerian Natural History Society of Edinburgh to oppose the theories of geologist James Hutton (1726-97) with whom he disagreed.
Thomson was appointed to the Regius Chair of Chemistry at the University of Glasgow in 1817. An experimentalist, he tried to prove the new atomic theories that were being formulated at the time, was the first to use symbols in chemistry and insisted his student undertake practical work at a time when this was most unusual.
He served as a consultant to the Scottish Excise Board, examining the production of whisky, and invented a saccharometer for assessing sugar content of the fermenting must. In 1820, he analysed a new zeolite mineral found at Old Kilpatrick, which was named Thomsonite in his honour. He published a History of Chemistry (1831) and other influential works, together with a critically-acclaimed history of the Royal Society.
Thomson died at Kilmun (Argyll and Bute) and lies buried in the Glasgow Necropolis. His eldest son, also Thomas Thomson (1817-78) became a noted botanist.