English scientist, theologian, and political theorist Joseph Priestley (1733 1804) made numerous contributions to chemistry, physics, and philosophy. Priestley, who was raised in Birstall, West Yorkshire, attended local schools before going to Daventry Academy, where he became very interested in natural philosophy. Priestley made significant scientific advances. His greatest-known discovery, made in 1774, was oxygen, which he dubbed "dephlogisticated air." His investigations into gases and their characteristics, which are detailed in "Experiments and Observations on Different Kinds of Air," greatly enhanced our knowledge of chemistry. Priestley also studied nitrous oxide and carbon dioxide, among other gases. In addition to his scientific interests, Priestley was a prolific writer on theological and political topics as well as a dissident clergyman. He received criticism for his Unitarian beliefs and his perceived radical religious ideas. Priestley was a liberal and democratic idealist whose political writings shaped the early American history.