Priestley was born in 1733 in Leeds into a strongly nonconformist family. By 20, he could read many languages, including Hebrew and Arabic, and in 1755 became a minister. Priestley had been brought up a Calvinist, but, like many nonconformists of his time gradually abandoned that stark doctrine. His studies in electricity (encouraged by Benjamin Franklin, who became a lifelong friend) led to him becoming a Fellow of the Royal Society in 1766, and the publication of his History of Electricity in 1767.
Priestley gave up being a clergyman in 1773 – he decided he could serve God better through science – and went to work for the Earl of Shelbourne, who was happy to fund Priestley’s research in return for services as child’s tutor, librarian and ‘literary companion’, in which latter capacity he accompanied Shelbourne to France in 1774.
Priestley was now an established natural philosopher, and it was inevitable that he would meet up with Lavoisier, the great French chemist. Priestley (who became a ‘lunatic’ when he joined the Lunar Society – see 1766: Erasmus Darwin entices Rousseau with a flower) may not have been the first thinker to appreciate that the world was interconnected through animal and plant life, but his work on just how it was interconnected was new: ‘the injury which is continually done to the atmosphere by [animals is] in part at least, repaired by the vegetable creation’, and the meeting with Lavoisier in Paris was to be of great importance in establishing our knowledge of how all living things are linked through respiration. Our modern debate about ecology, about climate change, is founded upon the discussion between these two men.
The previous year, Lavoisier had begun experimenting on the calcination of tin and lead, and had discovered that air itself was responsible for the increase in weight of the metals. But what was it in air that caused this increase? Priestley told Lavoisier that he had produced a pure form of air, ‘ an air five or six times as good as common air’. He thought he had discovered what he called ‘dephlogisticated air’, phlogiston being a theoretical substance supposedly released during combustion. What he had actually discovered was oxygen.
What Happened Next
Lavoisier realised Priestley was on to something and in 1775 gave Priestley’s discovery the name ‘oxygen’. Lavoisier, like Priestley, was a friend of Franklin, and used his political influence and scientific knowledge (his work on gunpowder was crucial) to help the American Revolution. As farmer-general of taxes, he also developed French agriculture. Come the French Revolution, Marat (see 1793: Charlotte Corday assassinates Marat) who disliked Lavoisier, ensured he ended up on the guillotine in 1794. The mathematician Lagrange pointed out that it took an instant to strike off a head that a ‘hundred years may not produce.’ Priestley stayed a believer in both Phlogiston and revolution for the rest of his life: his defence of the French Revolution, in reply to Burke (see 1774: Edmund Burke is enraptured by Marie-Antoinette) resulted in a Birmingham mob burning his house. He moved to Pennsylvania, where he died in 1804, confidently awaiting Christ’s Second Coming.