Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we take a closer look at the definitions and etymologies of scientific terms.  Today on Sciency Words, we’re talking about:


Earth.  Fire.  Air.  Water.  Only the Avatar can master all four elements.  Only the Avatar… or Antione-Laurent Lavoisier, the 18th Century French chemist.  As described in this article, Lavoisier originally intended to study each of the four elements in turn, starting with air.  But Lavoisier’s air research quickly “bent” the concept of the four elements so hard that the whole concept broke. And thus…

Lavoisier did not discover oxygen, but he did name it.  You see, when oxygen was first discovered in the early 1770’s, it was called “dephlogisticated air.”  That’s a mouthful of a name, but it made perfect sense to anyone who was familiar with the phlogiston theory of combustion.

Now I’m not going to waste your time explaining what phlogiston theory was, except to tell you that it was an updated-for-the-18th-Century version of the theory that fire is an element.  The important thing to know is that Lavoisier’s experiments on dephlogisticated air poked some pretty big holes in phlogiston theory, and so that theory had to be abandoned in favor of “oxygen theory.”

So where did the word oxygen come from?  Let me try to reconstruct Lavoisier’s thought process.  Among other things, Lavoisier found that burning stuff in “dephlogisticated air” tended to produce substances that were more acidic than the original reactants.  “Oxy” is Greek for acid.  So some sort of acid-generating process was occurring… an “oxy-genesis,” if you will.  Or “oxy-gen” for short!

The term Lavoisier actually used was principe oxygéne, meaning “the acidifying principle.”  The words oxygen and oxidation start appearing in English shortly thereafter, thanks mainly to translations of Lavoisier’s work.  But by that point, it was clear that oxygen was more than merely an acid-generating gas.  It had other properties too. Lavoisier demonstrated that oxygen played an important role in both combustion and animal respiration, as well as other natural processes like the rusting of iron.

But we’ll talk more about oxygen’s many abilities in next week’s episode of Sciency Words.

P.S.: Lavoisier also named hydrogen.  Burning “inflammable air” and “dephlogisticated air” together produced water.  “Hydro” is Greek for water.  So some sort of water-generating process was occurring… a “hydro-genesis,” if you will.  Or “hydro-gen” for short!

P.P.S.: And since you can make water by mixing two different kinds of air, water must not be an element.  Also, how can air truly be an element if there are different kinds of air? This whole four elements thing fell apart pretty quickly as Lavoisier continued his research.

9 responses »

  1. I find these paradigm changing events fascinating. Apparently phlogiston theory was already showing signs of strain by Lavoisier’s time, with people having to posit that maybe it had negative weight to explain some experimental results. Lavoisier’s experiments seemed to deal the death blow to it, and from what you describe, the whole ancient conception of elements.

    Although the ancients, seeing the science of today, might insist that the fundamental forces and associated elementary particles get more at what they were trying to accomplish with their elements and atoms, rather than the higher level concepts we now use those words for.

    Liked by 2 people

    • J.S. Pailly says:

      I feel like there’s a parallel between this and the time leading up to special and general relativity. People were finding problems here and there with phlogiston theory and other theories related to the classical elements, but these problems must have seemed like matters of detail until Lavoisier came along and offered a new, more expansive new theory.

      I also see a parallel with the modern concepts of dark matter and dark energy. Like dark matter and dark energy, phlogiston was this mysterious something that had whatever properties were needed to explain otherwise unexplainable observations about combustion.

      Liked by 2 people

      • It seems like physicists are pretty careful with dark matter and dark energy to keep them as placeholder concepts. Of course, just applying the label “matter” to dark matter has an assumption in it. It might have been better to go with “dark gravity” or something.

        The stubborn difference in measurements of the Hubble constant is another possible canary in the coal mine heralding some as of yet unfathomable paradigm shift.

        And quantum physics seems like the 800 pound gorilla lurking in the corner that we do our best to ignore unless we need something from it.

        Liked by 2 people

      • J.S. Pailly says:

        That is an amazing metaphor for quantum physics!

        But yeah, I feel like there are lots of little points of confusion in physics right now. Maybe each will turn out to have some easy explanation, or maybe we’re on the verge of the next big revolution in science. Who knows?

        Liked by 1 person

  2. Emily Faith says:

    Just wanted to let you know I love your blog. It’s fascinating and I always learn something from it. I like how your articles are always positive and wholesome : )

    Liked by 2 people

  3. Iamsaparza says:

    This post is very interesting😊😊!

    Liked by 1 person

  4. Kieran Paul says:

    Think of it one hundred billion galaxies can be seen with our instruments, many earth sized planets are in the visible universe – 2 billion trillion, how many are habitable, earth sized planets with oxygen?, water?, vapor,? life and radio waves with intelligentsia calling the shots. Such a discovery would be a turning point and change how we view the universe.

    Liked by 1 person

    • J.S. Pailly says:

      Those are big questions, my friend! And I think it’s only a matter of time before we find a truly Earth-like planet, with water and oxygen and something that we can definitvely identify as life. I’m far less confident about finding intelligent life, but who knows? The universe may surprise me.


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