Joseph Priestley {1733-1804} was a British-born clergyman and scientist. He discovered oxygen and conducted groundbreaking experiments with a variety of other gases. Priestley was a controversial figure in England, both religiously and politically, and he emigrated with his family to rural Pennsylvania in 1794. The home he built there included a laboratory. Priestley advanced the teaching of science, history, and religion, and he was an important force in the founding of the Unitarian movement in America.