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Joseph Priestley, 1733-1804

priestley.gif (12973 bytes)The English Unitarian minister and chemist, was born, a cloth-dresser's son, at Fieldhead in Birstall Parish, Leeds. At the grammar school he entered in 1745, Priestley learned Latin, Greek and improved on a system of shorthand. Both independently and with tutors, he became proficient in physics, philosophy, algebra, mathematics and a variety of ancient Near Eastern and modern languages. After four years at the Dissenting academy at Daventry, in 1755 he became minister at a small Presbyterian parish at Needham Market, Suffolk, and there wrote The Scripture Doctrine of Remission. In 1758 he went to Nantwich, and in 1761 became a tutor at Warrington Academy in Lancashire. Ordained in 1762, he was married that same year to Mary Wilkinson, the sister of the Welsh ironmaster, John Wilkinson. 

Priestley's reputation and contacts with the English intellectual world increased throughout the 1760s.His Chart of Biography (1765) won him a doctorate of laws from the University of Edinburgh and his experiments in electricity brought him into the Royal Society in 1766. While at Warrington he made several visits to London and there met Richard Price and John Canton. He also became the close friend of Benjamin Franklin who encouraged Priestley's work in science and politics. One result was Priestley's projected history of electrical experiments.

Priestley argued that writing a history of science was important since it could show how human intelligence discovers and directs the forces of nature. The history of science also illustrated the general progress of mankind. The History and Present State of Electricity, with original Experiments (1767) described a variety of electrical phenomena and introduced a number of his own conclusions on the nature of the scientific method.

Priestley's work with electricity also led him into other fields of science. In 1772 he published The History of the Present State of the Discoveries relating to Vision, Light and Colours as the first volume of a projected multi-volume series on the history of experimental philosophy. The work brought him an invitation to serve as astronomer on James Cook's second voyage. Because of Priestley's theological and political ideas, the invitation was retracted.

Priestley's skill  in the use of laboratory apparatus proved valuable in his study of the chemical properties of gases. His method of making soda water ("mephitic julep"), which he hoped would prevent scurvy on long ocean voyages, was of interest, but more significant was his discovery of a variety of new gases.

In 1772, Priestley presented the paper, "On Different Kinds of Air," to the Royal Society. It was this paper which established his reputation as a chemist. Two years later he prepared the first edition of Experiments and Observations on Different Kinds of Air, which he republished a number of times until 1790. Following up on the work of Joseph Black and James Cavendish, Priestley enlarged our knowledge of the chemical properties of gases. He differentiated between nine gases -- only three of which were previously known to science. Of particular significance was "dephlogisticated air" (oxygen) which he produced on August 1, 1774, by heating red mercuric oxide. It then became clear that air was not an element. Priestley isolated oxygen and observed its importance in combustion, but it was left to Cavendish and Lavoisier to appreciate the theoretical significance of his work.

In 1774, as literary companion, he accompanied Lord Shelburne on a tour of the continent and published the Letters to a Philosophical Unbeliever. But at home he was branded an atheist in spite of his Disquisition relating to Matter and Spirit (1771), affirming from revelation our hope of resurrection.

He was elected to the French Academy of Sciences in 1772 and to the St. Petersburg Academy in 1780. He became in that year minister of a chapel in Birmingham. Priestley's Birmingham years were his happiest and most productive. He was able to participate in the stimulating discussions and monthly meetings of the Lunar Society of Birmingham as well as pursue his interest in theological issues. His History of Early Opinions concerning Jesus Christ (1786) signaled renewed controversy since it defended Unitarianism and attacked such doctrines as the inspiration of scripture, the virgin birth, the Trinity and the atonement.

His reply to Burke's Reflections led a Birmingham Church and King mob to destroy his home and laboratory in 1791. Both Burke and Lord North expressed satisfaction at the developments at Birmingham -- Priestley accepted his losses with stoic dignity. He now settled at Hackney where he taught history and science at the New College, considered by many to be a hot-bed of sedition, republicanism and deism, He also succeeded Richard Price as the morning preacher at the Gravel Pit Chapel. In 1792 the French Assembly made him a citizen, and, although he declined the honors, he was also elected to the National Assembly. The war with France and the execution of Louis XVI in January 1793 undermined his position.

In 1794 Priestley and his wife moved to Northumberland, Pennsylvania where he constructed his new home and laboratory. Although he did not become a citizen and did not involve himself in the political affairs of the nation, Priestley was friends with both John Adams and Thomas Jefferson, the latter of whom saw Priestley as "one of the few lives precious to mankind."

Priestley died in Northumberland on February 6, 1804, and was buried in Riverview Cemetary. Kindly and soft-spoken, methodical and industrious, Joseph Priestley was convinced that the application of science could bring material progress to mankind. He was one of the 18th century's most outstanding experimental scientists. Although he supported civil and religious liberty and wrote seminal essays in those areas, he was never a leader in the English radical movement for parliamentary reform, yet he was perhaps the most prominent victim of the intolerance manifested by the supporters of the established order in the 1790s.

Resources
About Joseph Priestley's Disquisitions relating to matter and spirit
(1777)
Considerations on the Doctrine of Phlogiston
(1796)
Joseph Priestley (Chemical Heritage Society)
Joseph Priestley
(Spartacus)
Joseph Priestley, The Discovery of Oxygen
(Paul Halsall)
Letter from Benjamin Franklin to Priestley
(1774)
Letter from Thomas Jefferson to Priestley
(1803)

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