Joseph Priestley discovered oxygen, invented soda water, and refused to believe either mattered to chemistry's revolution
Joseph Priestley isolated oxygen in 1774 and gave the world fizzy water, yet he spent his later career defending the old phlogiston theory against the new chemistry his own gas had helped launch. The same restless mind wrote grammars, timelines, liberal political theory and the theology that helped found English Unitarianism.
Priestley was born on 24 March 1733 in the Yorkshire village of Birstall, close to Batley, the eldest of six children of a cloth finisher in a Dissenting family outside the Church of England. After his mother died he was raised largely by a wealthy, childless aunt, who hoped he would become a minister. He was precocious: at four he could flawlessly recite the Westminster Shorter Catechism, 107 questions with their answers, and he went on to learn Greek, Latin, Hebrew and a string of modern languages.
A serious illness around 1749 shook his Calvinist faith. Unsure he had experienced the conversion his church required, he came to reject predestination and embrace universal salvation, and his home chapel refused him full membership. The illness also left him with a lifelong stutter. At the Dissenting academy in Daventry, which he entered in 1752, he became a Rational Dissenter, and David Hartley's material theory of mind shaped his lifelong hope of proving religious truths scientifically.
His first ministry, in the Suffolk market town of Needham Market from 1755, went badly; the congregation drifted away once they grasped how unorthodox he was, and his aunt withdrew her support. Nantwich in Cheshire, from 1758, was happier. He ran a school, bought scientific instruments for his pupils, and wrote his own English grammar in 1761 because he despised the ones available. At Warrington's academy he befriended the potter Josiah Wedgwood, who later made a jasperware medallion of him, and in 1762 he married Mary Wilkinson.
In 1767 he found a way to dissolve carbon dioxide in water. Seven years later, by heating mercuric oxide, he isolated what he called dephlogisticated air. His loyalty to phlogiston left him increasingly isolated among chemists, but his thinking travelled in other directions: Bentham, Mill and Herbert Spencer drew on his metaphysics, and his 1768 Essay on the First Principles of Government is an early landmark of liberal thought. He died on 6 February 1804, having published more than 150 works.
Source: Joseph Priestley
