The Life and Works of Joseph Priestley

Take a deep breath.  Feel that? That’s oxygen, moving into your lungs and bloodstream.  Many scientists are credited with helping discover and name this element, including Antione Lavosier.  But the man who was the first to pin down this important gas is Joseph Priestley.  He performed experiments that also acknowledged photosynthesis.  He hasn’t had the easiest of lives, one full of political and religious torment.  He also did experiments on other things such as photosynthesis and carbonated water.  Still, somehow he managed to perform his oxygen experiments and make sure his name is forever written in our textbooks as one of the best scientists of his time.

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Early Life

“Leeds Portrait”, shows Priestley aged 35 as Minister of Mill Hill Chapel.

Joseph Priestly was born on March 13, 1733 in Birstall Fieldhead, England [3]. He was the oldest of six children born to Mary Swift and Jonas Priestley, a finisher of cloth. To ease the family’s burdens, Priestley was sent to live with his grandfather around the age of one. Five years later, he went back to home after his mother died. When his father remarried in 1741, Priestley went to live with his aunt and uncle: Sarah and John Keighley.  They were wealthy and childless and lived just three miles from Fieldhead. When Joseph was four years old, he could flawlessly recite all 107 questions and answers of the Westminster Short Catechism.  This showed that he was an extremely intelligent boy and absorbed almost anything put in front of him. His aunt decided to get the best education for him that they could.  They planned to have him become a part of the ministry. Joseph Priestley attended local schools where he learned Greek, Latin, and Hebrew.  He also improved on a system of shorthand writing, further showing his genius. Both on his own and with tutors to help him, he became proficient in physics, philosophy, algebra, mathematics and a variety of ancient Near Eastern and modern languages. He went to the Dissenting academy at Daventry for four years. In 1755, his aunt’s goal was completed when he became minister at a small Presbyterian parish at Needham Market, Suffolk [2]. There he 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. He gradually came to question the divinity of Jesus, while accepting much else of Christianity, in the process becoming an early Unitarian [3].  A Unitarian is someone who focuses for on the unity with God and doesn’t believe in the Trinity, which consists of the Father (God), the Son (Jesus), and the Holy Spirit.

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Joseph Priestley Memorial Chapel

The Chapel as it looks today.

Priestley’s religiousness carried over to the U.S. when he came here later in life.  The Joseph Priestley Memorial Chapel is the oldest church building in the Borough of Northumberland, PA.  The chapel was built in 1834 by members of the Unitarian Congregation and that included many descendants of Joseph Priestley’s grandson Joseph Raynor Priestley.  The chapel was used until the 20th century when the congregation size was too small to keep holding regular services.  It was used periodically for worship for Unitarians as well as a school house and Red Cross building.  Over the years many efforts to maintain the chapel were undertaken.  It still stands today; people can tour it and see diagrams of his oxygen experiments.  It is maintained by donations [5].

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Priestley in Politics

Priestley was also politically involved.  He was a supporter of both the American and French Revolutions. He saw them as the beginning of Armageddon, as foretold in the Bible. These views, which he made no effort to hide, were considered seditious, or traitorous, by English authorities and his neighbors. In 1791, a mob destroyed his house and laboratory in Birmingham because of his preaching that Armageddon was coming, and support of the revolutions.


This riot, along with growing threats and dangers, pushed him to decide to immigrate to the United States. With his sons he planned to set up a model community on undeveloped land in Pennsylvania, but that didn’t happen. He and his wife did, however, build a beautiful home with its own laboratory far up the Susquehanna River in Northumberland, Pennsylvania.

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Benjamin Franklin

Priestley’s first scientific work, The History of Electricity, was encouraged by Benjamin Franklin, who he had met in London. With these urgings from his new, greatly influential friend, Priestley began to perform experiments. At first they were merely to reproduce those in other reports and experiments done by other scientists. As he discovered things and became more scientifically adept, he did experiments to answer questions of his own. In the 1770s he began his most famous scientific research on the nature and properties of gases. At that time, he was living next to a brewery, which provided him with plenty of carbon dioxide to experiment on. His first chemical-related publication was a description of how to carbonate water, in imitation of some naturally occurring bubbly mineral waters.  Priestley began examining all the “airs” that might be released from different substances. In doing so, he made soda. Many, following Aristotle’s teachings, still believed there was only one “air.” The four elements of the world were air, fire, water, and earth. By making his own equipment and carefully manipulating the gases, Priestley isolated and characterized eight gases, including oxygen.  In addition, he contributed to the understanding of photosynthesis and respiration.

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Experiments (cont. 2)

The world recalls Priestley best as the man who discovered oxygen, the active ingredient in our planet’s atmosphere. In the process, he helped dethrone an idea that dominated science for 23 uninterrupted centuries: Few concepts “have laid firmer hold upon the mind,” he wrote, than that air “is a simple elementary substance, indestructible and unalterable.”

Antoine Laurent Lavoisier

Priestley fought with Antoine Lavoisier and his followers over how to interpret the results of experiments with gases. Priestley interpreted them in terms of phlogiston.  That’s the hypothetical principle of flammability that was thought to give metals their luster and ductility and was widely used in the early 18th century to explain combustion, calcination, smelting, respiration, and other chemical processes. Priestley gave qualitative explanations of these phenomena, talking, for example, about oxygen as “dephlogisticated air.” [4].  In a series of experiments culminating in 1774, Priestley found that “air is not an elementary substance, but a composition,” or mixture, of gases. This includes the colorless and highly reactive gas he called “dephlogisticated air,” to which the great French chemist Antoine Lavoisier would soon give the name “oxygen.”  It’s highly reactive due to the amount of electrons in its valence shell and plays a major part in chemical reactions required for daily life, like respiration, photosynthesis, and combustion.

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Experiments (cont. 3)

This was his results of the closed container experiments.

As he was doing these experiments, Priestley made an enormously important observation. A flame went out when placed in a jar in which a mouse would die due to lack of air. In other words, he had a flame and mouse in a sealed container.  As time went on, the mouse died and the flame went out.  We know now that that is because the mouse couldn’t breathe because there was no oxygen.  The flame went out for the same reason, since oxygen is needed for combustion.  He did another experiment when he put a live plant in the container with the candle and the mouse.  When the plant was exposed to sunlight, it would “refresh” the air, allowing the candle to burn down to a stub and the mouse to live on happily. Perhaps, Priestley wrote, “the injury which is continually done by such a large number of animals is, in part at least, repaired by the vegetable creation.” He didn’t know at the time that he just witnessed photosynthesis [6].  His research would pave the way for future scientists to look into this further.

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