Joseph Priestley

Joseph Priestley was an English clergyman and chemist who on 1 August 1774 isolated a colorless gas by heating red mercuric oxide with a burning lens, finding that it made a candle burn unusually brightly and that mice survived far longer in it than in ordinary air; working from the phlogiston theory of combustion current at the time, he called it dephlogisticated air. He visited Antoine Lavoisier in Paris that October and described the experiment, which Lavoisier repeated, reinterpreted and eventually named oxygen; Priestley never accepted Lavoisier's reinterpretation and defended phlogiston theory for the rest of his life. He is credited with identifying several other gases and with an early method for carbonating water. A supporter of the French Revolution and religious dissent, he had his house, laboratory and library destroyed by a loyalist mob in the Priestley Riots of 1791 and emigrated to the United States in 1794, where he died in 1804.