The New Chemistry: Crash Course History of Science #18

One of the problems with the whole idea of
a single Scientific Revolution is that some
disciplines decided not to join any revolution.
And others just took a long time to get there.
In the case of chemistry—the study of what
stuff is—a real scientific revolution, like
in the Thomas Kuhn sense, didn’t really
get going until the 1770s.
Until then, mainstream chemistry in Europe
was based on phlogiston theory, which may
be difficult to wrap your head around because
it is the opposite of how we understand chemical
reactions today.
To shake loose that particular scientific
status quo, it took the power of the Enlightenment,
and one of its most emblematic natural philosophers,
[Intro Music Plays]
If the 1600s was the century of science in
Europe, centered on London, then the 1700s
was the century of philosophy, centered on
This new philosophy largely consisted of a
movement called the Enlightenment—dated
by some from 1715, when France’s powerful
“Sun King,” Louis the Fourteenth, died,
to 1789, when the French Revolution started.
The Enlightenment was a shift in ideas about
knowledge, away from traditional sources of
authority, like the Church, and toward the
kind of scientific rationality described by
This aspect of the Enlightenment is summed
up by the catchphrase sapere aude, or “dare
to know.”
This suggested that knowing is something you
should do—a moral good.
This was an “Age of Reason.”
The Enlightenment was also about social values,
such as individual liberty, the progress of
civilization, and religious tolerance, including
the separation of church and state.
The Enlightenment at times even fed into anti-religious,
specifically anti-Catholic, feelings, setting
the stage for a later perceived break between
science and religion.
The term “Enlightenment” was coined by
German writer Johann Wolfgang von Goethe,
and it was used by Voltaire, and later by
Thinkers like them—called les philosophes,
or “the philosophers”—met in scientific
societies, literary salons, and coffeehouses.
The philosophes saw it as their job to discover
the laws of nature—the natural law that
helped guide human behavior.
They dreamed of a “republic of letters,”
a world ruled by rational thought and guided
by reasoned debate.
So, yes, if you remember episode two: the
philosophes were kinda like the Presocratics.
The ideas of the Enlightenment undermined
the authority of kings and churches and helped
set the intellectual stage for the soon-to-come
revolutions in the United States, France,
and Haiti.
But the Enlightenment was also about increasingly
centralized state power and colonization of
non-Europeans, which we talked about two episodes
Statistics, for example, was developed at
this time to serve the interests of nation-states
and early corporations.
So we can also call this the Age of Empire…
Perhaps no object better represents the Enlightenment
than the ambitious book named the Encyclopédie.
Edited by Jean d’Alembert and Denis Diderot
from 1751 to 1777, the twenty-two volume Encyclopédie
attempted to organize literally all of the
knowledge available to humanity.
The Encyclopédie physically demonstrated
three big ideas: First, knowledge is cumulative.
Humans add new knowledge to our collective
pool all the time.
Second, knowledge is recordable.
We can transmit knowledge through things like
And third, knowledge is political.
Diderot, like Bacon, believed that knowledge
should be used to alleviate human misery.
Diderot hoped to “change the general way
of thinking” by popularizing recent achievements
in science and technology and combating superstition.
He wanted to use knowledge to help people
He also thought that all traditional beliefs
should be reexamined “without sparing anyone’s
But strict censorship by the state made any
explicitly anti-religious articles impossible,
so Diderot had to cleverly slip in critiques
of the church.
For example, in the cross-reference for the
entry on the Eucharist: “see cannibalism.”
Now, the Encyclopédie systemized knowledge
in a neat way, but it was largely qualitative,
describing things according to values—for
example, what a good ship looks like.
But Enlightenment thinkers increasingly dreamed
of quantification, or describing things in
numbers—like units of length, mass, heat,
and so on.
But for quantification to work, you have to
have an agreement about how to measure things.
In other words, you have to have standards.
The meter, for example, was defined by a commission
of scientists in France in the 1790s as one
ten-millionth of the earth’s meridian through
The commission included Pierre-Simon Laplace,
who wrote the five-volume
Celestial Mechanics, starting
in 1799.
This greatly expanded Newton’s work on classical
mechanics, opening up a range of topics to
the problem-solving power of calculus.
Celestial Mechanics became a sort of Principia – volume two.
And in order to actually measure the meter,
the commission sent out two guys, Pierre Méchain
and Jean-Baptiste Delambre, to make measurements.
…I’m not good at French.
This was a time of widespread war in Europe.
Méchain and Delambre struggled against skirmishes,
yellow fever, and imprisonment—but they
got the job done.
And along with standards, measurement required
new instruments, like the barometer and electrometer,
as well as new ways of interpreting data,
AKA statistics, which were also pioneered
by Laplace.
By the end of the eighteenth century, physics
was already well on its way to rationalization,
quantification, and even standard measurement.
But what about chemistry?
In the late 1700s, natural philosophers believed
that chemical reactions occurred thanks to
an ether—a colorless, odorless, “self-repulsive,”
extremely fine, and therefore hard-to-measure
fluid—called phlogiston.
According to phlogiston theory, this ether
was released during combustion.
For example, a burning candle was thought
to release phlogiston.
If you covered that candle with a jar, the
flame would go out, because the air would
become saturated with phlogiston and couldn’t
absorb any more.
This is exactly the opposite of how we now
understand it: that the flame goes out because
it’s used up all of the oxygen, which is
necessary for a chemical reaction.
Likewise, it was thought at the time that,
when plants grew, they absorbed phlogiston
from the air.
When their wood was burned, it released phlogiston
back into the air.
Or when we ate them, our bodies released phlogiston
through respiration and body heat.
In this system, “phlogisticated air” or
“fixed air” was what we would now call
carbon dioxide.
Joseph Black isolated fixed air in 1756.
“Dephlogisticated air,” on the other hand,
was oxygen.
This system worked pretty well to explain
chemical reactions qualitatively—why they
seemed to appear a certain way—but no one
could quantify phlogiston.
And minor anomalies in phlogiston theory kept
adding up.
For example, mercury gained weight during
combustion, even though, by releasing phlogiston,
it should have lost weight.
The person who changed chemistry from a qualitative
discipline to a quantitative one was Antoine-Laurent
de Lavoisier.
A good example of an Enlightenment natural
philosopher, Lavoisier was born to a noble
family in Paris in 1743.
He studied law but was obsessed with geology
and chemistry.
Lavoisier also worked on the metric system.
Lavoisier first presented research on chemistry,
in a paper about gypsum, to the French
Academy of Sciences in 1764.
In 1768, the Academy made Lavoisier a provisional
Two decades later, he would become the founder
of the “new chemistry,” revolutionizing
the entire discipline.
ThoughtBubble, show us what this means:
Lavoisier knew phlogiston theory well.
But he began his chemical research with
the hypothesis that, during combustion, something
is taken out of air rather than put into it.
That hypothesis turned out to be correct,
and that something turned out to be oxygen.
Lavoisier’s tested his hypothesis by accounting
for inputs and outputs in chemical reactions—a
perfect example of the eighteenth-century
quantification of science.
And Lavoisier also discovered that the mass
of matter remains the same even when it changes
form or shape.
Which is very important!
Working carefully over years, he generated
the first modern list of elements.
He named oxygen in 1778, hydrogen in 1783,
and silicon—merely a prediction at that
point—in 1787.
In fact, Lavoisier and his allies developed
a whole new nomenclature for chemistry, in
“Inflammable air” became hydrogen.
“Sugar of Saturn” became lead acetate.
“Vitriol of Venus”—which had also been
called blue vitriol, bluestone, and Roman
vitriol—became copper sulfate.
Yeah, the new naming system was less fun than
the old one.
But it was more rational:
the terms better described the underlying
stuff they pointed to.
“Copper sulfate” meant a compound of sulfur
and copper.
Lavoisier published the textbook Elementary
Treatise of Chemistry in 1789, which taught
only the new chemistry.
In the introduction to his book, Lavoisier
also separated heat and chemical composition.
So water is water whether it’s heated up
to steam or cooled down to ice.
He understood that heating something up doesn’t
always change what it is, fundamentally.
To explain these state changes, Lavoisier
made up a new ether, which he called the
Caloric could penetrate a block of ice, melting
it into water by pushing the ice particles apart.
Thanks Thought Bubble.
Spoiler: caloric is not thought to be a real
thing today.
(Many people wish calories weren’t real,
but, here we are.)
Led by the prominent English chemist Joseph
Priestley, these old-timers kept modifying
phlogiston theory so that it could rationally
account for chemical reactions without falling
apart, due to the whole phlogiston-in versus
oxygen-out thing.
Well into the 1780s, many chemists still
believed in phlogiston—which no one had
actually seen or measured—simply because
it was familiar.
What changed their minds?
Well, Lavoisier and his allies published results
that favored their system.
But more importantly, the students who learned
from them could only speak the language
of the new chemistry.
The phlogiston believers were increasingly
Thus in a couple of decades, phlogiston moved
from the center of chemistry into exile.
With the new chemistry, Lavoisier brought
the discipline into the system of rational,
experimental science dreamed up by methodologists
such as Bacon and fleshed out by Newton.
Outside of chemistry, Lavoisier was a noble
with a powerful state job: he worked at the
hated tax collection agency of the French
kingdom, known for being both secretive and
He profited from his job there, helping fund
his chemical research.
But the French Revolution broke out in 1789,
and being an aristocratic tax collector was
not a good look.
Lavoisier was tried for defrauding the people
of France.
And the judge denied the appeal to save his
life, despite his immense contributions to
knowledge, declaring that: “The Republic
needs neither scientists nor chemists; the
course of justice can not be delayed.”
Lavoisier died by guillotine in 1794.
His friend, mathematician Joseph-Louis Lagrange,
said of Lavoisier’s death: “It took them
only an instant to cut off his head, but France
may not produce another such head in a century.”
Now, how was Lavoisier so successful at setting
up the new chemistry as a paradigm?
Well, he had a lot of support!
Marie-Anne Pierrette Paulze, AKA “Madame
Lavoisier,” was born into a noble family
in south-central France in 1858.
And she contributed significantly to Antoine’s
She translated his texts into English, and
after Antoine’s death, she published his
complete papers, securing his legacy in the
Madame Lavoisier eventually remarried another scientist, Count
Rumford, a physicist who had a role in shaping
But she insisted on keeping Lavoisier’s
name to show her allegiance to the man she
Also, Madame Rumford is way less cool.
After the Lavoisiers, a new generation of
thinkers continued to develop their ideas,
in France and beyond.
Notably, John Dalton observed that the ratio
of elements in reactions were often made up
of small numbers, meaning that chemical elements
are in fact discrete particles, not fluids.
He called these particles chemical atoms—true
indivisible units.
And Joseph Fourier published the Analytical
Theory of Heat in 1822, using calculus to
describe how heat flows.
Fourier also discovered the greenhouse effect,
or the capture of the sun’s radiation in
the earth’s atmosphere.
Next time—we’ll classify plants’ sexy
parts, disintegrate a willow tree, and debate
whether whole species can … go extinct.
Join us for biology before Darwin!
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In Missoula, MT. And it’s made possible with the help of all these nice people.
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Crash Course is a Complexly production.
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100 thoughts on “The New Chemistry: Crash Course History of Science #18”

  1. Good overview. I hope it's followed up eventually with some notes as to why the term "Enlightenment" turned out to be extremely inaccurate despite a few major scientific, mathematical, and philosophical breakthroughs.

  2. And Laplace also incidentaly derived a now useful transform. At one point in his tome on celestial mechanics, he needed a particular result, so he took a day or so off to pen a slim volume on math. This was mostly ignored in favor of his major work, so the Laplace Transform was unknown until the 1940s, when it supplanted the Heavyside Transform, which was useful but has no mathematical basis.

  3. "Age of Empire"? C'mon, man, I've been sitting over here with Age of Empires 2 on my hard drive for like a year now and you drop the 's'? You're killing me. 😛

  4. Always love a good science history lesson. Love learning from this channel, even about branches that I never truly studied up on(engineering, astronomy, world history, etc.)

  5. Copper sulfate is a compound of copper, sulfur and oxygen. The video says, “copper and sulfur”. This is in the portion describing the new chemical nomenclature.

  6. Can you folks fix the sound balance? The intro music is so much louder than Hank that I have to turn the volume down significantly for it not to be painful…and then turn it back up so I can hear him when Hank starts talking again. Good content – as always – but that volume difference is uncomfortable.

  7. Oh you are saying everything in chemistry was discovered by west… Didn't talk about chemistry mentioned in Ayurveda and unni which is older than 17th century.

  8. No, Hank, your French pronunciations were pretty impressive!! You must've worked hard on that one. I appreciate your efforts.💚

  9. I don’t think we should judge phlogiston and caloric theory tooooo harshly. It combined combustion, oxidation of metals, and cellular respiration into an early theory of redox reaction. The fact that these are all connected and related is definitely not obvious. Seriously, the idea that explosions, plants growing, and eating a cheeseburger are related seems crazy at first.

  10. Fun Fact! Count Rumford, a.k.a. Benjamin Thompson, was born in America, specifically in Worcester Massachusetts. He spied on the American side without getting caught and later earned his title in England. He had a fascinating life.

  11. I didn't know Goethe coined the term "Enlightenment" (I associate him with Romanticism, and a weirdly philosophical color theory that was not physically true). I also did not know Goethe was a philosopher at all.

  12. I thought the 19th century was really the age of colonization, therefore empire. (sorry about the comment wall, as usual).

  13. I'd love to know what evidence inspired Lavoisier's "something is coming out of the air" guesswork. Scientific progress never (rarely? Is there a scientific version of mathematics' Ramanujan?) comes from nowhere — it's incremental, even when it's revolutionary.

  14. Saying "Sapere aude!" and not name-droping Kant instantly *shaking my head*. (I just couldn't help myself.)

  15. The revolutionaries of the french revolution killed one of the greatest scientists in history? Those MOTHERFUCKERS!!!

  16. Fourier also was the first to use series methods to describe systems (particularly thermodynamic ones), a contribution so important they were named after him (Fourier series) and contributed to the foundation of partial differential equations.

    Dude has to be one of the most important scientists nobody outside of his fields really knows about.

  17. Is there a video about Bacon
    on this channel ? He is always talking about him, but I have never heard of this guy …

  18. Crashcourse, i love you from the bottom of my nerd heart, but the lack of effort that you put into pronouncing non-english words is appalling and embarrassing

  19. Tfw everyone thinks the first french Republic was secular when it was actually led by members of the cult of the supreme being yet also atheistic.

  20. So we only really made significant progress in modernising chemistry because Lavoisier refused to 'teach the controversy' around phlogistons, and made the old school of thought go extinct. Something to think about for creators of the US curriculum around biology.

  21. Golly that you did not forget Marie-Anne! Both Lavoisiers, husband and wife, were a tandem and she carried on with science even after his death… Isn't it unfair that, until recently, Antoine-Laurent was the only one who was remembered…

  22. Somewhere I read that Laplace was a teacher of geometry and/or mathematics at a military academy. Among the cadets at his class there was a little nerdy Corsican whom, as I have heard, would go on to attain far greater things…

  23. One instant to sever his head. Decades for another equal one to appear. Luckily, Marie-Anne was there, and Antoine-Laurent was finally remembered post-Thermidor, when the beheading craze of the far left was as good as gone!

  24. And Scheele? Shining the spotlight on France puts Sweden definitely on the fringe… Unless. Surely. Carl von L. awaits in Uppsala next week – so sad that on the 100 crown banknote they have replaced his face with Garbo's…

  25. Everything that made France truly great got thrown in the fire in that revolution. They really threw the baby out with the bathwater. Turns out executing everyone of ability in your country just isn’t great for your long term success…

  26. The more I learn about the history of science, the more I realize the white men are truly superior, there can be no doubt. We Asians should learn from them, as much as possible.

  27. Phlogiston is as wrong as describing electronics by invoking positively charged holes.

    But aether was a totally different theory. Nothing to do with phlogiston theory nor chemistry in general. Off topic for this video.

    The idea was that if light is a wave, what is waving? A wave on the ocean is the motion of salt water. So what is moving in a wave of light? Answer: aether. Which was then replaced by space-time itself, rather than a substance occupying space.

  28. Just one point on your maps at 0:57 – at that time London is indeed the capital of the Kingdom of England (as this was before the UK existed) but the Kingdom included Wales during the whole of the 1600s. Your map shows England only, without Wales. At the time, Wales was a part of England in every way. It's only really since 1801 and the United Kingdom was Wales once again seen as seperate from England, as a constituent nation of the UK.

  29. Diderot is my hero. Also, your mention to "madame Lavoisier" felt forced and shoehorned, it seemed clear that you were just doing it to meet the obligatory gender quota.

  30. I actually like the English term for the Enlightenment better than the German version coined by Goethe: "Die Aufklärung". The same term is used in Germany when you give someone the birds-and-bees-talk, which is why this always leads to a giggle in the classroom when the Enlightenment is the topic.

  31. Tip, the letter "c" in classical Latin is always pronounced as "k". So Newton's Principia is pronounced as "prinkippia".

  32. As a French, I studied half of this in school. Well, I wish I had Hank as teacher. It's waaaay more interesting explained by him

  33. Wikipedia isnt reliable.

    It isnt cited by reliable sources. It is anonymously contributed to by self confident people who dont use substantiated if any resources.

    Wikipedia is generally garbage with a significant lack of knowledge

    With Significant portions of false knowledge

    And is highly biased
    Based on the moderators themselves.

  34. That’s so interesting for revolutionary France, as in the 1789 revolution they were SUPER obsessed with rationality and progress.

    Then again, that’s probably why he made that appeal

  35. A tragic omission is not mentioning Joseph Fourier's: "Fourier Transform"… today it's used billions of times in nearly every single machine, device and form of communication. From streaming your audio on YouTube to keeping an aeroplane stable in the air!

  36. One more woman is missing in this picture: her name is Emilie du Châtelet. She's famous for translating Newton's principia into French (remember – French was spoken throughout the courts of Europe at that time), but more importantly, it was her who decided to write the Math in the manner of Leibnitz, and doing so she made Newton much, much more accessible. Her 'translation' was much more than that, and she also published a textbook that made the laws of physics clearer still (institutions de physique). [incidentally, she's also famous for being Voltaire's mistress. Yet another woman more famous for who she scoodylipoops* with than what she actually does].

    *scoodylipoops: yes, I'm a long time fan of your and your brother's work.

  37. So few women mentioned in this series. I'm sure it's not the writers or Hank leaving them out intentionally but rather the result of rampant sexism during the times discussed. Women must have made real contributions but getting published or recorded in history was nearly impossible. A real shame.

  38. Interesting historical paralleles here. Huge growth in knowledge was stymied by politcally correct intellectuals. The salon culture was destroyed by the leftist revolutionaries and their gulloitine.

  39. "According to phlogiston theory, this ether was released during combustion"

    Oh haha Valve, I just got that joke. The Phlogistinator? Cute.

  40. I encountered the Phlogiston theory of heat with the work done by Count Rumford of Bavaria. He presented his findings regarding heat produced during the boring process of a cannon to the Royal Society of London. The belief by then was "as matter is subdivided, phlogiston or caloric will flow out of the material." Count Rumford observed that when the boring device becomes blunt, as long as the boring device works against the cannon, even if there is no more further subdivision of matter (as the hole did not become bigger) still heat was produced. The caloric theory of heat or the Phlogiston theory died after that. This episode provided me the information that Lavoisier created the term "phlogiston". He is the first husband of Madame Lavoisier. Count Rumford was able to put and end to the life of the Phlogiston theory but he was not able to extinguish the LOVE Madame got for her first husband, as Madame Lavoisier continued to carry that family name even if she married Count Rumford. Quite romantic?

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