The 250th Anniversary of the discovery of Oxygen

 

Dr. Sliderule at Joseph Priestley's Laboratory at Bowood House,

the site of the isolation of the gas element Oxygen by Priestley

on August 1, 1774

On August 1, 2024, we will celebrate a momentous event in the history of science, the 250th Anniversary of the isolation of the element Oxygen.

Joseph Priestley was in the laboratory he had constructed at Bowood House in Wiltshire, England on August 1, 1774.  He was the librarian and tutor for the Earl of Shelburne. Priestley, a Unitarian Minister and polymath was already well known for his scientific and other scholarly work in many diverse disciplines.

 
However, Priestley’s most important and lasting contribution to science is based upon the discovery he made on this date at this location when he obtained a colorless gas by heating red mercuric oxide. He found that a candle would burn and that a mouse would thrive in this gas in a closed container.  He called it “dephlogisticated air,” based upon the belief that ordinary air became saturated with phlogiston once it could no longer support combustion and life.  The phlogiston theory was originally postulated by the German chemist, Georg Ernst Stahl (22 October 1659 – 24 May 1734), and has subsequently been discredited.

The following October, Priestley accompanied his patron, Lord Shelburne, on a tour through Belgium, Holland, Germany, and France, when in Paris Priestley informed the French chemist Antoine Lavoisier how he obtained the new “air.” This meeting between the two scientists was highly significant for the future of chemistry. Lavoisier immediately repeated Priestley’s experiments and, between 1775 and 1780, conducted intensive investigations from which he derived the elementary nature of oxygen, recognized it as the “active” principle in the atmosphere, interpreted its role in combustion and respiration, and gave it its name. Lavoisier’s pronouncements of the activity of oxygen revolutionized chemistry.

To see a video on this subject see this link.

Joseph Priestley on Public Television

Wed, Aug 19 at 8 pm, PBS

(Check your local PBS station for broadcast times)

            

Patrick Page as Joseph Priestley                      Patrick Page, Ava Deluca-Verley and Hugo Becker

 as Joseph Priestley, Marie Anne and Antoine Lavoisier

The Mystery of Matter: Search for the Elements is an exciting PBS series about one of the great adventures in the history of science: the long (and continuing) quest to understand what the world is made of—to identify, understand and organize the basic building blocks of matter.

Three hour-long episodes introduce viewers to some of history’s most extraordinary scientists: Joseph Priestley and Antoine Lavoisier, whose discovery of oxygen—and radical interpretation of it—led to the modern science of chemistry; Humphry Davy, who made electricity a powerful new tool in the search for elements; Dmitri Mendeleev, whose Periodic Table brought order to the growing gaggle of elements; Marie Curie, whose groundbreaking research on radioactivity cracked open a window into the atom; Harry Moseley, whose discovery of atomic number redefined the Periodic Table; and Glenn Seaborg, whose discovery of plutonium opened up a whole new realm of elements, still being explored today.

The Mystery of Matter shows us not only what these scientific explorers discovered but also how, using Broadway-caliber actors to reveal the creative process through the scientists’ own words, and conveying their landmark discoveries through re-enactments shot with working replicas of their original lab equipment. Knitting these strands together into a coherent, entertaining whole is host Michael Emerson, a two-time Emmy Award-winning actor.

Mystery of Matter:  Search for the Elements will be shown on PBS on Wednesday, August 19, 2015 from 8PM to 11PM. (3-1 hour shows airing back to back)

Georg Ernst Stahl and the Phlogiston Theory

Just to keep things balanced, I have an engraving of Georg Stahl hanging on my office wall right near my Priestley likenesses, some of these likenesses I have blogged about earlier.  I have Georg hanging there to put things in perspective.  

Georg Ernst Stahl (1659-1734) was born at Ansbach. He was an eminent chemist and physician and is best know as the foremost proponent of the now defunct and discredited phlogiston theory.  

The phlogiston theory was originally postulated by Johann Becher in 1667. It hypothesized that flammable materials contained phlogiston, a substance without any discernible properties, including, mass, or any other physical properties whatsoever.  When the flammable material was combusted the phlogiston dissipated and the material returned to its "dephlogisticated" state called the calyx or true state.

Joseph Priestley was also a lifelong proponent of the phlogiston theory, and, in fact, upon isolating a substance from mercuric oxide with heat, called it "dephlogisticated air" (oxygen).

It was Antoine Lavoisier in France who showed that combustion requires a gas that has weight. This substance he named oxygen, and in demonstrating that it did have mass he had made the phogiston theory obsolete.  The fact that Lavoisier became obsolete after the French Revolution by losing his head is the subject of a blog yet to be composed.

In any case, the conclusion is that even great minds make mistakes. In Priestley's case it was his clinging to an obsolete theory even after it had been clearly discredited.  In Scientific Correspondence of Joseph Priestley the letters Priestley wrote of his observations from experiments he had performed show his numerous mistakes and ill formed conclusions. Yet, through it all, through all the imperfect observations and incorrect thinking, he was able to accomplish so much. It is a lesson to be learned by all.  Mistakes are normal in the course of discovery. They are essential!  And every assumption must be treated with suspicion.