1733-1804

English clergyman, author, and chemist who first isolated such gases as oxygen, nitrous oxide, and sulfur dioxide. Priestley studied for the ministry and eventually became the best-known and most controversial Unitarian minister in Britain. In the 1760s he began scientific research into electricity and then optics, and also started work on the nature and characteristics of gases. Entirely self-taught in science and a very prolific author on theological, scientific, and political matters, Priestley read widely and corresponded with numerous scientists in Britain and abroad. Priestley remained the most famous chemist in the world until Frenchman Antoine Lavoisier's "new chemistry" supplanted his theories by the 1790s. An ardent supporter of the American and French revolutions, Priestley was forced to leave England in 1794 and settle in Pennsylvania.