What was joseph priestley experiment

An Englishman by birth, Priestley was deeply involved in politics and religion, as well as science. When his vocal support for the American and French revolutions made remaining in his homeland dangerous, Priestley left England in and continued his work in America until his death. Some 2, years ago, the ancient Greeks identified air — along with earth, fire and water — as one of the four elemental components of creation. That notion may seem charmingly primitive now.

But it made excellent sense at the time, and there was so little reason to dispute it that the idea persisted until the late 18th century. It might have endured even longer had it not been for a free-thinking English chemist and maverick theologian named Joseph Priestley.

Priestley was hugely productive in research and widely notorious in philosophy. He invented carbonated water and the rubber eraser, identified a dozen key chemical compounds, and wrote an important early paper about electricity. His unorthodox religious writings and his support for the American and French revolutions so enraged his countrymen that he was forced to flee England in He settled in Pennsylvania, where he continued his research until his death. 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.

In a series of experiments culminating in , Priestley found that "air is not an elementary substance, but a composition," or mixture, of gases. Among them was 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 is hard to overstate the importance of Priestley's revelation.

Scientists now recognize 92 naturally occurring elements-including nitrogen and oxygen, the main components of air. They comprise 78 and 21 percent of the atmosphere, respectively. In the midth century, the concept of an element was still evolving. Researchers had distinguished no more than two dozen or so elements, depending on who was doing the counting.

It wasn't clear how air fit into that system. Nobody knew what it was, and researchers kept finding that it could be converted into such a variety of forms that they routinely spoke of different "airs.

The principal method for altering the nature of air, early chemists learned, was to heat or burn some compound in it. The second half of the s witnessed an explosion of interest in such gases. The steam engine was in the process of transforming civilization, and scientists of all types were fascinated with combustion and the role of air in it.

British chemists were especially prolific. In , Joseph Black identified what he called "fixed air" now known to be carbon dioxide because it could be returned, or fixed, into the sort of solids from which it was produced. In , a wealthy eccentric named Henry Cavendish produced the highly flammable substance Lavoisier would name hydrogen, from the Greek words for "water maker.

Finally in , Daniel Rutherford found that when he burned material in a bell jar, then absorbed all the "fixed" air by soaking it up with a substance called potash, a gas remained. Rutherford dubbed it "noxious air" because it asphyxiated mice placed in it. Today, we call it nitrogen. But none of those revelations alone tells the whole story. The next major discovery would come from a man whose early life gave no indication that he would become one of the greatest experimental chemists in history.

In , Priestley was offered a ministry in Leeds, Englane, located near a brewery. He found a way to produce artificially what occurred naturally in beer and champagne: water containing the effervescence of carbon dioxide. The method earned the Royal Society's coveted Copley Prize and was the precursor of the modern soft-drink industry. Joseph Priestley was born in Yorkshire, the eldest son of a maker of wool cloth. His mother died after bearing six children in six years.

Young Joseph was sent to live with his aunt, Sarah Priestley Keighley, until the age of She often entertained Presbyterian clergy at her home, and Joseph gradually came to prefer their doctrines to the grimmer Calvinism of his father. Before long, he was encouraged to study for the ministry. And study, as it turned out, was something Joseph Priestley did very well. Aside from what he learned in the local schools, he taught himself Latin, Greek, French, Italian, German and a smattering of Middle Eastern languages, along with mathematics and philosophy.

This preparation would have been ideal for study at Oxford or Cambridge, but as a Dissenter someone who was not a member of the Church of England Priestley was barred from England's great universities.

So he enrolled at Daventry Academy, a celebrated school for Dissenters, and was exempted from a year of classes because of his achievements.

After graduation, he supported himself, as he would for the rest of his life, by teaching, tutoring and preaching. His first full-time teaching position was at the Dissenting Academy in Warrington. Although obviously brilliant, original, outspoken and, by one report, of "a gay and airy disposition," Priestley had an unpleasant voice and a sort of stammer. That he made a living through lectures and sermons is further evidence of his extraordinary nature. In , he was ordained and married Mary Wilkinson, the daughter of a prominent iron-works owner.

She was, he noted, "of an excellent understanding, much improved by reading, of great fortitude and strength of mind, and of a temper in the highest degree affectionate and generous; feeling strongly for others and little for herself. Priestley traveled regularly to London, and became acquainted with numerous men of science and independent thought, including an ingenious American named Benjamin Franklin, who became a lifelong friend.

While it was Priestley who isolated this new gas, it was Lavoisier who grasped its profound implications. Over the next 15 years, he would make oxygen the foundation of a whole new chemistry, showing that it was a key ingredient in both air and water, and that fire was not an element, as the ancients believed, but a process of combining with oxygen.

Centuries later, scholars continue to debate who deserves credit for discovering oxygen. Or Lavoisier, who understood what the new gas meant? While Priestley never accepted the revolutionary importance of his own discovery, he did make a critical finding about the importance of oxygen to life on earth. It was a fundamental contribution to environmental science. As his scientific activity waned, Priestley took an ever greater interest in politics, offering vocal support for the American cause in the Revolutionary War and, a decade later, for the French rebels who overthrew King Louis the XVI.

He fled to America and spent the last ten years of his life in Pennsylvania. By doing so, Johnson notes, Priestley set a precedent for the many other intellectual exiles who would follow. To see the full Priestley story, select Watch Online to go to pbs. Joseph Priestley. Birth of a Scientist Joseph Priestley was a man of wide interests and boundless curiosity.

Video: A Momentous Encounter - Biographer Steven Johnson describes how a meeting with Benjamin Franklin led to a lifelong friendship — and inspired Priestley to become a scientist in his own right. Boyle's Air Pump. The Discovery of Air From electricity Priestley next turned his attention to the study of air. Video: The Discovery of Air - How air came to be a subject scientists thought was worth studying.

Soda Water In , Priestley left his position as a tutor in Warrington to take up a new post as a minister farther north in Leeds. Antoine Lavoisier. The red calx of mercury. A Mysterious New Gas By , Priestley had begun to experiment with a curious substance called the red calx of mercury. During this experiment, the CO 2 levels remained above 2, ppm and reached a maximum of 6, ppm, yet yellow streaks were observed on the maize plants by the end.

It is possible that damage to the maize may have also reduced the photosynthetic yield and the production of O 2 towards the end of this experiment. This study, therefore, provides an insight into the use of plants to maintain a self-sufficient biosphere, such as would be required on the surface of extra-terrestrial bodies without an atmosphere, and the potentially detrimental effects of a dramatically increased CO 2 concentration.

This simple experiment is a humble reminder of the integral relationship between animal and plant life on Earth, in which the former owe their existence to the latter. Without the presence of plants within the sealed environment, the concentration of O 2 would have fallen and CO 2 concentration would have risen to a point at which human life could no longer be supported.

Whilst O 2 sustains human life and plants maintain its level within the atmosphere with remarkable efficiency, the fundamental role of photosynthesis is arguably taken for granted. Deprived of plants, the subject within the container would have succumbed to the effects of severe hypoxaemia. The experiment reminds us of our total dependency upon plants, and the ecosystem in which they exist. All authors discussed the results and implications and commented on the manuscript at all stages.

All authors read and approved the final manuscript. National Center for Biotechnology Information , U. Journal List Extrem Physiol Med v. Extrem Physiol Med. Published online Sep 4. Author information Article notes Copyright and License information Disclaimer.

Corresponding author. Daniel Martin: ku. Received Mar 14; Accepted Sep 4. This article has been cited by other articles in PMC. Abstract Background Photosynthesis maintains aerobic life on Earth, and Joseph Priestly first demonstrated this in his eighteenth-century bell jar experiments using mice and mint plants. Methods A single male subject was placed within a sealed, oxygen-depleted enclosure Results After 48 h, the oxygen concentration within the container had risen to Conclusions This simple but unique experiment highlights the importance of plant life within the Earth's ecosystem by demonstrating our dependence upon it to restore and sustain an oxygen concentration that supports aerobic metabolism.

Background The Earth supports a fragile ecosystem, and its inhabitants depend for their survival upon complex interactions between them, which have developed over billions of years. Methods Formal ethical approval was not sought for this experiment as it was designed for the purpose of a television demonstration; consent was implied through the subject's involvement in the project and participation in the event.

Open in a separate window. Figure 1. The sealed container with plants, the subject and external artificial lighting. Table 1 Taxa, number of leaves and leaf area of the plants placed within the container. Scientific plant name Common name Number of plants Total number of leaves Total upper leaf area cm 2 a Z. Flamingo flower 2 24 , Chrysopogon zizanioides Vetiver 2 1, , Aechmea Cv. Bromeliad 14 20, Eruca sativa Rocket 16 11, Lactuca sativa Lettuce 16 11, Mentha spicata Mint 5 1, Ferns Ferns 9 72 10, Totals 10, 1,, Results The concentration of O 2 in the container rose throughout the experiment, peaking at Figure 2.

Change in oxygen concentration within the container over time. Figure 3. Figure 4. Discussion The design of the biological ecosystem in this study was such that human life was sustained for 48 h and the initial hypoxic environment restored to one of near-normal O 2 concentration. Conclusions This simple experiment is a humble reminder of the integral relationship between animal and plant life on Earth, in which the former owe their existence to the latter.

Competing interests The author declares that they have no competing interests. References Blankenship RE. Origin and early evolution of photosynthesis. Photosynth Res.