Priestley's discovery named 'oxygen'



As luck would have it, Lord Shelburne was setting off on a trip to the continent, and took Priestley along. In France, Priestley met Lavoisier and described his discovery. It turned out to be the clue Lavoisier needed to develop his theory of chemical reactions — the "revolution" in chemistry that would finally dispel the phlogiston theory. Burning substances, Lavoisier argued, did not give off phlogiston; they took on Priestley's gas, which Lavoisier called "oxygen" from the Greek for acid-maker.

By then, however, Priestley had returned to England, where he escalated his support for the American revolution and for highly unorthodox religious views. Those positions were a source of embarrassment for Lord Shelburne. Priestley left his service in 1780, moving to Birmingham and taking a position as head of a liberal congregation called New Meeting.

His new location brought him into contact with numerous luminaries including Erasmus Darwin, grandfather of Charles, the great architect of evolutionary theory. James Watt and Matthew Boulton — who were about to transform society with their steam engine — were there, as was Josiah Wedgwood, the famous potter, who supported Priestley's chemical experiments. Birmingham also boasted a distinguished scientific discussion group, the Lunar Society, which met on nights of a full moon so that the members could see their way home.

Priestley's encouragement of the French Revolution, together with his increasingly controversial theology and attacks on the doctrine of the trinity, eventually became too notorious for safety. In 1791, an alcohol-fueled mob of royalists burned the New Meeting house, and then Priestley's home. The scientist and his family barely escaped. They fled to London, but eventually it proved no safer. Priestley's sons could not find work and emigrated to Pennsylvania, where they hoped to found a center for free-thinking Englishmen.

Finally Joseph and Mary followed them, setting sail for America on April 8, 1794. Priestley turned down the offer of a teaching position at the University of Pennsylvania in Philadelphia, and instead built a house in the remote hamlet of Northumberland to be near his sons. The area was decidedly rustic.

There Priestley continued his research, isolating carbon monoxide (which he called "heavy inflammable air") and founding the Unitarian Church in the United States. For the most part, he led a quiet and reflective life—especially after his friend Thomas Jefferson was elected president in 1800.

During his final trip to Philadelphia, he told the Philosophical Society that "having been obliged to leave a country which has been long distinguished by discoveries in science, I think myself happy by my reception in another which is following its example, and which already affords a prospect of its arriving at equal eminence." His words proved prophetic. A colloquium held on the centennial of Priestley's discovery of oxygen led to the founding of the American Chemical Society—today the world's largest scientific society—in 1876.

On February 3, 1804, Priestley began an experiment, but found himself too weak to continue. He went to his bed in his library, never again to emerge. On February 6, he summoned one of his sons and an assistant. He dictated some changes in a manuscript. When he was satisfied with the revisions, he said "That is right. I have now done." Minutes later he died painlessly, ending what Jefferson called "one of the few lives precious to mankind."