In my readings about the history of chemistry, I've come across the story of the incredible chemist and scientist Joseph Priestly. My question is just about one of his discoveries - the discovery of carbon monoxide.

Several places make mention of Priestly's discovery of carbon monoxide. However the best I can find is some vague language, like

There Priestley continued his research, isolating carbon monoxide (which he called "heavy inflammable air") and founding the Unitarian Church in the United States.

... but without a shred of detail!

I am wondering, can anyone provide some insight as to how Priestly went about doing this? Where can I find some literature about his experiments and thought process?

  • 3
    $\begingroup$ As a Unitarian, I doubt Priestley was "Priestly". $\endgroup$
    – user55119
    Sep 1, 2020 at 1:39
  • 1
    $\begingroup$ Do a Google Book search with key words: "carbon monoxide" "inflammable air" and you will find tons of high quality results. google.com/… $\endgroup$
    – AChem
    Sep 1, 2020 at 4:59

2 Answers 2


Converting my comment into an answer

It's true that Joseph Priestley is often credited to be the first one to synthesize carbon monoxide in 1772. Apparently when he synthesized it, he didn't realize it was a separate "air" (entity). So, he called it "combined fixed air". This was done by heating charcoal. For some time this was confused with "inflammable air" that is hydrogen, and also with methane since all three gases were flammable. Later other chemist refined the synthesis process and later it was identified to be a unique entity and was named carbon monoxide (but was erroneously called carbonic oxide at that time). You can find more details on how carbon monoxide was redefined here.

But point to note, there were several people often attempted to synthesize carbon monoxide before Priestley. There is a rich history of carbon monoxide mentioned here but since Priestley’s experimental success predominantly from his ability to design ingenious apparatuses and his skill in their manipulation, he is often credited to discover gases which no one has able to synthesize before. He gained particular renown for an improved pneumatic trough in which, by collecting gases over mercury instead of in water, he was able to isolate and examine gases that were soluble in water. Apparently, he is credited to discover 10 gases. For his work on gases, Priestley was awarded the Royal Society’s prestigious Copley Medal in 1773.

You can find more information from below articles:

  1. Christopher P. Hopper, Paige N. Zambrana, Ulrich Goebel, Jakob Wollborn, A brief history of carbon monoxide and its therapeutic origins, Volumes 111–112, 2021, DOI: 10.1016/j.niox.2021.04.001.
  2. McKIE, DOUGLAS. “JOSEPH PRIESTLEY (1733-1804), CHEMIST.” Science Progress (1933- ) 28, no. 109 (1933): 17–35. http://www.jstor.org/stable/43420726.
  3. https://web.lemoyne.edu/~giunta/ea/PRIESTLEYann.HTML
  4. https://www.britannica.com/biography/Joseph-Priestley
  5. https://journals.physiology.org/doi/full/10.1152/ajplung.00310.2013

Here is a short description on how Joseph Priestly isolated carbon monoxide. He took an oxide of iron and charcoal, heated them together over a furnace in a gun barrel, than he passed the gases this reaction produced through limewater to remove the carbon dioxide. The remaining gas burned with a blue flame. He was able to weigh it and found it was slightly lighter than common air. He wrote about his findings in "Experiments And Observations Relating To Various Branches Of Natural Philosophy, With A Continuation Of The Observations On Air". This book can be bought on Amazon.


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