How Joseph Priestley inspired early America. And why he's needed now more than ever The next time you take a deep breath, think for a moment of Joseph Priestley, the 18th-century British scientist widely credited with discovering oxygen.As Steven Johnson explains in his engaging study of Priestley, The Invention of Air: A Story of Science, Faith, Revolution, and the Birth of America,  the circumstances surrounding Priestley's signature achievement are "far more vexed than the standard short-form biographies suggest." That's because "discovering 'oxygen' is not like 'discovering' the Dead Sea Scrolls....It is closer to, say, discovering America: the meaning of the phrase...