Joseph Priestley
English chemist
March 13, 1733 - February 6, 1804

Joseph Priestley was born in England and raised by an aunt after his mother died when he was only six years old. He was educated as a minister, and i n 1761 was appointed as a teacher of languages in the Dissenting Academy at Warrington.

Priestly loved to experiment, and even with a meager salary managed to purchase an air-pump and an electrical machine. In 1766 he met Benjamin Franklin during a visit to London. That meeting encouraged Priestley in his pursuit of a scientific career. He soon began his studies of "fixed air," carbon dioxide, and performed his famous experiment with mercuric oxide that resulted in the isolation of "dephlogisticated air" (oxygen). Without formal training he isolated more gases than anyone before or since. 

Priestly was a liberal clergyman, and his views were not well-received in England. He came to the United States in 1794 and settled in Northumberland, Pennsylvania. He spent the last ten years of his life living quietly in Pennsylvania.