In this debut episode of Chain Reaction, we go on a thrilling journey through the earliest chapters of chemistry’s history starting with the quest to make gold from abundant metals. Chemical historian Larry Principe guides us through the winding past of alchemy – its evolution across Greek, Islamic, and European traditions, and the secrecy, symbolism, and ambition that defined the craft. From coded manuscripts to the social politics that ultimately pushed alchemy underground, Larry reveals how hands-on experimentation shaped the scientific mindset we now take for granted.
Then the episode fast-forwards through centuries of discovery – from identifying elements, to early gas experiments, to the birth of the periodic table, to the atomic revolution – guided by science writers Sam Kean and Cathy Cobb. It’s a whirlwind introduction to how humans learned to understand, categorize, and ultimately master matter.
Transcript of this Episode
INTRO
Margot: Wow wow wow. I am so excited. Ok. AHEM. Welcome to Chain Reaction, a new podcast from the American Chemical Society where we link chemistry’s past to its future! I’m your host Margot Wohl.
With me today is Sam Jones, executive producer of this pod and another ACS podcast you may have heard of, Tiny Matters.
Sam J: Hey Margot. Happy to be here. And excited to join you and help kick things off! Let’s get right into it and explain what this new podcast is all about.
Margot: Let’s do it! Chain Reaction is about putting the world of chemistry into perspective. How does chemistry fit into all facets of our everyday lives? How has it changed over time? And, of course, where is it headed?
Sam J: We will be dispatching a collection of miniseries. Each miniseries takes one big theme and breaks it down in a series of four episodes. And in each episode we have some amazing guests. Chemists and other scientists talking about their fields - helping us make sense of the chemistry underlying so many of the cool things happening around us and being discovered. We’ll’ also have Historians who take us through pivotal /moments/ in chemistry. And that nicely leads us into our first miniseries about the chemical enterprise. How did the field of chemistry get started? What world events drove and continue to drive its existence? How have the faces of chemistry changed over the decades? And more.
Margot: We’ll begin with the origins of chemistry — how we as humans started playing with matter and how that led us to modern chemistry. And I thought there would be nowhere better to start our very first episode than in a chemistry lab recreating something that ancient chemical enthusiasts did centuries earlier!
Sam J: Heck yea. Let’s head to the lab!
Margot: Ok! We are in the lab of Larry Principe in Baltimore Maryland.
Larry Principe - in lab: I am a professor of the History of Science and Technology and a professor of chemistry at Johns Hopkins University. Oh gee, I should have practiced that in advance.
Margot: We are in a small room, standing by a fume hood, about to perform an experiment.
Margot - in lab: Can you explain what we're about to do?
Larry Principe - in lab: I'm gonna show you a process that comes from the very earliest days of alchemy. This process comes out of a papyrus, written probably in the third or fourth centuries AD in Greco-Roman Egypt. It's to make something that's known as the divine water. By taking lime, so that is calcium hydroxide, and sulfur in equal amounts. Mixing them with, well, the text says that we should either use vinegar or the urine of a young boy.
Margot - in lab: Okay. Which did you use?
Larry Principe - in lab: Uh, neither. I used water…Okay. Um, when I first did this experiment, I did try it with urine. [laughter]
Margot: Ok - so Larry takes a silver coin…
Larry Principe - in lab: A Canadian maple leaf coin.
Margot: He drops it in the yellow tinged “divine water”...
Larry Principe - in lab: And we're gonna let it sit for eight minutes or so.
Margot: Eight minutes later (in French accent a la spongebob squarepants)
Larry Principe - in lab: And now we have a gold maple leaf.
Margot - in lab: Wow. I’m convinced.
Margot: So the surface of the once silver coin gets covered in a kind of tarnish made of silver sulfide. I kid you not Sam, the coin was really a convincing, smooth, shiny, gold! So this is the part where I tell you that I’ve now started a counterfeit gold business and will be resigning as host of this podcast.
Sam J: Already? But you just started, Margot!
Margot: Haha Ok! I’ll stay. Especially because we have a lot of chemistry to explore together on “Chain Reaction”. And today’s episode is about the early origins of chemistry. Some people think that a big turning point in early chemistry was the emergence of alchemy - or the attempt to transform matter into something entirely new, often the goal was to convert “boring” metal into gold. Just like how Larry transformed the silver silver coin. After demonstrating that ancient transformation, I sat down with Larry to talk about those early days - when tinkerers tried their hand at transmuting metals and learned a lot along the way.
INTERVIEW 1
Margot: So you are a historian of chemistry and so I'm wondering if you can take us all the way back in time in a time machine back to pre alchemical days. Uh, what were people doing? Were they messing with chemicals? Were they doing some sort of chemistry before alchemy?
Larry Principe: Yeah, well probably. I mean, I don't know if we would call it chemistry as such, but certainly working with materials. I mean, obviously people from as far back as you want to go, were in contact with all kinds of materials in the natural world things like brewing or textile making, dying, Well, clearly there's a lot of metal working, where people had accumulated for thousands of years knowledge about how to make alloys, how to refine ores into metals, that sort of thing.
Margot: Oh, okay. Um, so then what sparked the alchemical rage? When does that begin and why?
Larry Principe: I think this happens probably in the fourth century AD in Egypt. And Egypt at that time was a Roman colony, Greek speaking and a great mixing pot of cultures and languages and ideas. And I think what happens at that point is that this ancient tradition of Egyptian metalworking - just think of the kind of things you see in Egyptian exhibits, in museums metal working brought to a very high degree - it combines with Greek philosophical thought about matter. What is the structure of matter? What do transformations actually mean? How do transformations happen? When you put those two things together, that's when I think you get something that we can call alchemy or chemistry where you have a theory about the way the natural world works, you have a body of knowledge from experience, you put the two together, you say, “Okay, what can I do now? What can my theory tell me that I'm actually capable of doing?”, and then try it out.
It's something more than just an accumulation of know-how and of recipes to transform matter. It's this union of hand and of mind, of theory and of practice.
Margot: Why did they become so fixated on making gold out of non-gold metals?
Larry Principe: Well, there's straight away, there's an economic interest, uh, in making gold and silver, actually the precious metals.
Uh, there is a basic concept that's fairly widespread throughout all periods of alchemy that metals were sort of intended to be gold. That gold is the purest, the most perfect metal. And so the lesser metals, so iron, tin, lead and so forth, are imperfect. And so it's a, it's sort of a natural process of perfection to purify, to recombine the ingredients that make up the metals to get to gold.
Of course along the way, alchemists were doing a lot of other things: making medicines, making cosmetics, making dyes and acids and salts and alloys, sort of all the things that you can imagine, uh, chemists doing.
Margot: So then can you take us through alchemy and its transformation through the centuries from when it began to when it ended or transformed, if you will.
Larry Principe: Mm-hmm. Historians tend to break up the history of alchemy, at least in the Western world, into three periods: the Greek period - first, second century and up to about the seventh or eighth century, the Islamic period from the eighth century up until the 14th even the 15th century, and then the Latin European period which starts in the 12th century and goes on to about the 18th century.
Margot: So, who are some of the big players in alchemy? Tell me about some of the most influential people along the way.
Larry Principe: One of the people I find really fascinating, was a Greco-Egyptian alchemist by the name of Zosimos.
Margot: Great name.
Larry Principe: Yeah. Uh, he was born in Panopolis, which is now Akhmim on the Nile. And we have quite a number of writings from him that survive in fragments unfortunately. It said that he wrote 28 books on alchemy.
He fascinates me because he seems to have such a keen mind. He's asking the kinds of questions about the transformation of matter that it would take centuries afterwards to get answers to - really, until, until the modern age. He asked, why is it when you take mercury that's silver colored and sulfur that's yellow, and you put them together, you get something that's black and then you sublime it and it's red. And he, and he sort of yells at his contemporaries, “Instead of wasting your time with other things, you should be trying to figure out why this is so.”
Margot: Right. Because you think if you mix them together, you get an average.
Larry Principe: An average, right. Mm-hmm. But no, he recognizes that this is not the case. And you could see him struggling with ideas about how do we predict the behavior of substances when they combine chemically. So I think he's a fascinating character.
Margot: Cool.
Larry Principe: So, the next big stage of alchemy, where it really becomes a self-sufficient self-standing discipline, is in the Arabic speaking world. So this is from the eighth century onward. So what happens is, with the rise of Islam, the Islamic Empire spreads out and conquers much of the Greek world.
Margot: I see.
Larry Principe: And they're finding this wonderful stuff in Greek. They're fascinated by it and there are huge movements called translation movements to turn this material into Arabic. And at the same time, fascinated with this thing called “kīmiyā”, which they then start calling “al-kīmiyā”. That's why we have two different words that “al” is just the Arabic definite article.
Margot: That's just “the”, right?
Larry Principe: It’s just “the” stuck onto, uh, the Greek word.
So lots of very important Arabic authors for alchemy. Al-Razi, who produced a catalog of all these substances, classifying them as salts and borax and alums and metals and gems
And also a, a rather peculiar, well, a name attached to a large, large number of, uh, Islamic, alchemical treatises is Jabir. It turns out that the real Jabir, we don't know was he a real person or not.
But the texts that we have that have his name on them, were written over a period of about 200 years, so they're clearly not the work of one person unless he was really successful with finding a, a way to extend life.
Margot: The elixir of life.
Larry Principe: Yeah. Yes, exactly. Um, so probably written by a school of people, but extremely important texts. Uh, new theories about how we might transform the metals, new ideas about where the metals come from, how substances are produced and what the structure of matter actually is. And these have enormous impact on European alchemy when this Arabic material gets there starting in the 12th century.
Margot: Okay, take me there.
Larry Principe: So, there's a period of time that we now call the Renaissance of the 12th century. It was a time when Europe population exploded, when universities were founded, when Europeans had a sufficient amount of stability that they started looking outward of, “What's the rest of the world like??
And of course, what do they come in contact with, they come in contact with this towering tradition of Islamic civilization and Islamic learning. Okay. And so we now have a second translation movement of people going to Spain, to Sicily, to the Levant, to collect Arabic treatises and translate them into Latin.
All the sciences and the technology that there just seems to be this incredible thirst for in the 12th and 13th century in Europe. And it's in Europe that alchemy really has its greatest flowering. When you have tens of thousands of alchemical texts written by tens of thousands of alchemists all over Europe working on any number of projects in this search to find out what can human beings actually do to the material world. And so we find in alchemy some of the first ideas that human beings can actually control the natural world, change the natural, make things better.
Margot: There is some pushback though, right?
Larry Principe: Now. There is, in fact. In 1317, Pope John the 22nd, according to the story, convened a debate very much along the kind of debate that you would have in the universities at the time between those who said, yes, alchemists can make true gold and those who denied that it was possible. Anyway, apparently the people who were trying to defend alchemy didn't do a particularly good job of it and so, Pope John the 22nd issues a decretal saying that alchemists can make things look like gold, but they can't make true gold. And what he's really worried about more than anything else is he's worried about the stability of the currency.
He's worried that some clever alchemist is gonna make something that the average person cannot tell from gold, coins will be minted out of it, and therefore the basis of the economy will be disrupted, very severely.
Margot: No gold standard.
Larry Principe: Out, out the window. Right?
Margot: Yeah.
Larry Principe: So, in fact, he, he, he sets up a punishment. For those who have sold false gold, he says, anyone who has sold alchemical gold and silver as true gold and silver must immediately get an equal quantity of true gold and silver, bring it to the public treasury for distribution to the poor.
Margot: Hmm. Okay. I like that. Yeah, that's a nice law. So you've been speaking about some of your research and I'm curious what that looks like when you're trying to research alchemy, how do you go about doing that?
Larry Principe: Well, I, I, in some cases, it's sort of an embarrassment of riches because virtually any archive I go to in Europe will have alchemical manuscripts. Alchemy was so widespread, so many people were practicing it, it would take an army of scholars to go through even a fraction of the manuscripts that are out there to be read.
But you know, when I started this work, I came up with a kind of crazy idea. Some people thought it was crazy, um, that if you really wanted to know what were alchemists doing, it would take two things. You needed to take the writing seriously, first of all, and back in the 1980s when I was starting this, the writings were not always taken seriously.
They were sort of dismissed as imagination or fantasy or just magic. People just made stuff up without actually doing anything practically. So I thought, okay, we need to read these texts, try to read beneath the surface because some of them are written quite secretively, so they're sort of in a kind of code, which makes it doubly difficult.
So reading the text is one thing, so the library part of it, the archival part of it. But then bringing it into the laboratory. What were they actually doing? And I figured the only way really to do this was to try to replicate some of their processes. It's not always easy. There are all kinds of obstacles in the way.
For example, now when I want a chemical, I, we would all just order it from the chemical company, right? But, their materials were coming, usually natural products. Um,
Margot: Probably not very pure, right?
Larry Principe: Certainly not very pure. In fact, one of my major things that I discovered is that many of the processes that they describe that give results that seem totally impossible if you have a knowledge of chemistry. Totally impossible. If there's the right impurity, they work. And you know anyone who's worked in a chemical laboratory long enough in organic chemistry, you know that sometimes a little bit of the wrong material can catalyze a reaction to go completely in the wrong direction from what you want.
And so there's a kind of dialogue between the library, between the text, the written record, and the laboratory. You go back and forth between the two. And one of the things I do find, however, is that what I see in the laboratory often makes the text make so much more sense.
Margot: Really.
Larry Principe: You understand? Why did they pick that word? Oh, that's why you see something, you know, chemistry. My, my students laugh at me when I tell them, “I think chemistry is the most sensual of the sciences.”
Margot: Okay…
Larry Principe: Because, right? We're all interested in qualities of things, what things look like. Um, and I think most chemists have a deep sense of this. We like getting a jar of crystals at the end of the day, something beautiful. Well, the alchemists were the same way. They really paid attention to the appearances of their substances. And sometimes when you're just reading the text, you don't see how closely related to visual experience it is until you've done the visual experience.
Margot: So you were saying that some of these texts are kind of like hard to parse through because they were trying to keep them secretive. So what are some of the ways that they were describing what they were doing without giving away a recipe?
Larry Principe: There are, there are huge numbers of ways that they try and do this. Sometimes it's by leaving out a section of the process. Sometimes it's by mixing up the order of the process so that it's given in the wrong order.
Margot: Oh my gosh.
Larry Principe: Sometimes it's dividing up the process between two different books.
Margot: So why share it at all if you're.
Larry Principe: Yeah. You know, this is, this is what, if you really wanna be secret, you don't publish anything. Right? But these texts are both to conceal and to reveal. They sort of are so excited about what they're doing. They're seeing themselves as part of this lengthy tradition. It goes back, let's say, to Zozimos and the Egyptian alchemists. And so there's a sort of cred that you get by publishing something like this, but you're not giving it all away. There are also sort of bizarre metaphorical codes. So instead of calling gold, gold, they'll call it sun. In one text I was working on, nitric acid is called Red Dragon and if you think about how it was made by heating up potassium nitrate with ferrous sulfate, you get this red nitrogen dioxide gas, so you think about a dragon, well, it's corrosive, it's burning and it's red. Right?
Margot: It's like coming out of the mouth of the dragon.
Larry Principe: Exactly. Why not call it red dragon? In some cases there would be these extended fanciful accounts of a red dragon devouring something, or a gray wolf, or a queen and a king doing such and such, but they're not imaginary. It's reveal and conceal. What some people thought was that alchemists were just maybe a little cracked, and so they couldn't talk in any other way.
Margot: All that mercury.
Larry Principe: Right. All that mercury, right, right.
Margot: Yeah.
Larry Principe: But if you take a single alchemist, for example, look at his published writings - they're virtually impossible to understand. But maybe you can find some of his private papers, a notebook or letters, and they're perfectly clear.
Margot: Okay.
Larry Principe: The kind of thing that a chemist today could follow.
Margot: Mm-hmm. I see. So when does alchemy start to become less cool?
Larry Principe: Usually we point to the 18th century, the early 18th century for a number of reasons. The one thing I have to be really clear about is nobody ever proved that you couldn't make gold out of lead. There's not some new theory that suddenly comes up. It's not a scientific argument. I think it's a social and a political one that, as chemists started professionalizing, when chemistry became a discipline in the French Academy of Sciences, for example, where it was guaranteed a certain number of seats at the table.
Yeah, there was a necessity being part of the state apparatus to have a certain kind of authority. And a certain kind of respectability. And so alchemy gets tarred with a very bad brush, and it's all fraud. Now, we tended to believe this for a very long time, that, you know, that alchemy just got shoved out the door and suddenly now it's chemistry.
What I discovered in my travels through France looking at private papers is that virtually every single chemist, people whose names are recognized as chief chemists of the 18th century, were still trying to make gold. But they did it on the quiet.
Margot: I see.
Larry Principe: Because it wasn't something you talked about anymore.
Margot: Mm, I see. What would you say is the main legacy of alchemy?
Larry Principe: Wow. I think there's so many. Cataloging the natural world. What are the, what is the range of substances that exist out there? The basic operations of chemistry: distillation, crystallization, solution, all of those, most of the apparatus in chemistry is pretty consistent. If you look at the kind of things that were being used, let's say by Islamic alchemists in the ninth or 10th century, chemists are still using the same apparatus in the 19th, even into the early 20th. So there's that.
But I think there's something else that I've begun thinking about much more. We talk about the scientific revolution of the 16th and 17th centuries where telescopes, microscopes, anatomy, all the famous figures, Boyle, Newton, Galileo, Kepler, they're all living in this time. How many people were actually doing dissections? Probably not a lot of people. How many people had telescopes in microscopes? Not very many people. How many people had distillation equipment? Lots.
We had people in their attics, in their basements, men, quite a lot of women making pharmaceuticals for their personal consumption, for their family's consumption. But they're engaging with the natural world through chemistry, primarily through the arts of distillation and crystallization.
Experimentation, that is hands-on activity with the natural world, is key to the development of the scientific worldview we have today. If you believe that's true, then you have to realize that the vast majority who were dealing with that experimentalism, were doing it through alchemy.
BRIDGE
Sam J: Margot, I kept thinking during this whole interview - it is great that this goal, of making gold from other metals, drove early progress in chemistry. But…wouldn’t it be super frustrating to be an alchemist and never achieve your goal of making gold from other metals? And, although a lot of time has passed, I’m assuming it’s still not possible, right?
Margot: Well, it wasn’t possible. This really surprised me, but chemists and physicists still haven’t stopped trying to achieve that goal. And with the advent of particle colliders, they were one step closer. For instance, in the 1980s, none other than Nobel Prize Winner Glenn Seaborg and colleagues at the Lawrence Berkeley National Laboratory made a very small amount of gold by shooting high energy particles at Bismuth. The finding was actually presented at an ACS national meeting in 1980. And just this year, CERN reported making gold by colliding lead atoms together at almost the speed of light.
Sam J: Ok, so maybe not the kind of transmutation that alchemists were looking for - these recent experiments were making nuclear changes to atoms by using a lot of energy - not mixing chemicals together hoping to get gold that way.
Margot: Yes. Scientists had to come to a new understanding of what chemicals are made of at the fundamental level to achieve a new level of mastery over matter. And how did we get there? Well, I talked with historians and writers Sam Kean and Cathy Cobb about that next chapter in chemistry’s journey.
Sam J: Ooo you know how much I love science history, and I’ve actually spoken with Sam a number of times about a range of wild science history topics, so I am psyched. Let’s go.
INTERVIEW 2
Margot: So a big part of understanding our chemical world was in finding out like what is it made of? So when did chemists really start to grasp that there were these unique entities called Elements?
Sam Kean: So the early attempts to find elements were just sort of an extension of alchemy; they were just kind of mixing things together. Every once in a while they would come up with a new combination that would produce a new substance. Hennig Brand actually sort of famously and grossly discovered phosphorus in his own urine by distilling that down. So, you know, they, they were running some unusual experiments. Um.
Margot: It was yielding results.
Sam Kean: It was yielding results. You can't argue with the results. In the late 1600s, you have people like Robert Boyle who were developing the idea that there is a compound and that's different from, you know, a, a simpler substance.
Margot (narration): And Boyle fortunately had a sister who was also into experimentation — including alchemy — and he moved in with her.
Cathy Cobb: …And his sister had a laboratory already set up. So he went there and they together worked on many things. He thought taste was a way of describing a chemical. Don't do
Margot: Don't do that.
Cathy Cobb: Don't ever do that. He wrote a book called The Skeptical Chemist. Isn't that a lovely name? The Skeptical Chemist. And in it, he seemed to be saying that there were separate elements that were not, just the elements of Aristotle: fire, you know, smoke…
Margot: Captain Planet stuff like Right? Like air, water, fire.
Cathy Cobb: Yeah. That stuff. He said, “nah, there have to be individual particles that make up everything else.”
Sam Kean: But really not until the late 17 hundreds that scientists really understand that there were entities you couldn't break down further into simpler things. Then you had Joseph Priestly, who was, you know, a preacher, kind of a rabble rouser. He was like an everyday person who just happened to be really interested in chemistry and experiments with gases, especially Priestly was very famous for those.
Margot: Right. So what did he discover when he was working on gases?
Sam Kean: So the big thing he discovered was oxygen. In fact, he discovered several different gases and was really the first expert on things that, things that we breathe.
Margot: Uh, yeah, that's pretty important. Oxygen.
Sam Kean: Yes.
Margot: How did he know that he was like discovering elements?
Sam Kean: So he lived behind a brewery, so they were making beer, carbon dioxide was a byproduct of this. So he would get carbon dioxide from them in some cases.
He often did these experiments in a gun barrel, which was sort of the industrial container of its day. Very strong, um, could withstand a lot of heat and pressure if, you know, something had gone wrong. Uh, If he had mixed two things he probably shouldn't have mixed, a gun barrel was not going to explode like maybe a glass beaker would. And then he would bubble them under water, uh, catch them in a bottle and then he would just expose mice or other things to these gases and kind of just see what happened.
Margot: And why was he exposing them to these gases? What was he trying to figure out?
Sam Kean: You know, without modern chemical equipment and, uh, knowledge, that was just a quick way to tell, are these gases benign? Are they poisonous?
Margot: Right, right, right, right. Yeah. I kinda remember hearing that when he isolated oxygen, he was like, oh, this is the one that keeps us alive.
Sam Kean: Yes. Yep.
Margot: Because the mouse is still alive.
Sam Kean: Yep. Exactly.
Margot: And the other ones did not fare so well.
Sam Kean: Yes. Yeah. Eventually though, it got more systematic when you get to Humphrey Davy, who used electrolysis to find new elements. So he would take a mineral, run electricity through it, you know, jolt it, shock it, run a current through there. It would break down and then he could investigate the breakdown substances and he was able to discover several metals that way.
Margot: Ah, okay.
Sam Kean: Yep. Yeah.
Margot: That’s pretty cool. So then they're finding these elements, but I know that at some point, they have something to help them, right? And, and that's the spectroscope. Can you tell me about how that came to be and what they discovered using that new technology?
Sam Kean: Yeah, basically the spectroscope was a more systematic way to do it. So the spectroscope, essentially you heat an element up and it produces light from that, and each element produces its own individual light signature. It's sort of like a barcode of light, and Bunsen and Kirchhoff were the ones who started using that process on a regular basis and just finding element after element that way, because they had this new tool.
Margot: Right, so like all of a sudden they can just categorize things based on these light bands, right?
Sam Kean: Yeah, they had a very good tool to be able to break them down and to get them separated and yeah, to really figure out what they had inside different minerals. And Bunsen actually invented his famous burner, the Bunsen burner - you know, every chemistry student's favorite, uh, toy - uh, he invented that because it gives off heat without giving a glow of light so it wouldn't interfere with the light they were trying to look at and separate out. So that's, he, that's why he was motivated to invent that was because of this work that he was doing.
Margot: Oh, I had no idea. That makes so much sense! Um, okay, so they're finding all these elements, but how do they start to understand how these elements are relating to each other?
Sam Kean: People started noticing patterns with a few elements. So you have an element like strontium. When that was discovered, uh, someone noticed that its weight happened to fall exactly between that of calcium and barium. And strontium had similar chemical properties to those elements, so it would react in a similar way when it was exposed to different substances, uh, you know, different properties, like melting points, stuff like that.
They seemed to behave like each other. And again, their weight being right in between the two seemed a little suspicious. So people said, well, something is going on here. So they had what they called triads, but they would find three elements with similar properties. So calcium, strontium, and barium were one.
Another triad was chlorine, bromine and iodine. And then sulfur, selenium, tellurium was another triad. So you, when you start to get these triads, they knew something was going on and it gave them a bit of a handle on at least clustering them together. It's sort of like a network graph that you see nowadays.
You can kind of put a triad up here, a triad down here. We're not really sure about the connections between them, but we can at least cluster them and put them in groups by themselves. So it was an organizing principle, but it wasn't universal. Yeah.
Margot: Okay. But we know, of course, at some point we get the periodic table so how do we get to that stage of understanding how the elements relate to each other?
Sam Kean: Yeah, I mean the big name here obviously is Dmitri Mendeleev, who is the father of the Periodic Table. He wasn't the first one to come up with a system like that. There were three or four precursors to that. But he, he gets the credit for it because he did a few important things.
One was that he incorporated far more elements than anyone else had before, partly because he was a specialist in metals. And most of the periodic table is metals, so he was able to really make refinements and kind of figure out, uh, how to organize those metals, whereas if you weren't a specialist in that, it would probably seem more jumbled to you.
Margot (narration): Here is Cathy Cobb on Mendeleev.
Cathy Cobb: He started looking at where these chemicals were similar. And he put them on little cards and put 'em up on the wall and, he said, look, I can see, trends, you know, or things match, and his genius was that he left blanks. And the periodic table, which is what eventually evolved out of it, is amazing because it has predictive powers.
Sam Kean: He even described the properties of elements that we didn't know about yet, which was a bold thing to do. And there was actually one case famously with Gallium, where a French scientist discovered it, uh, published some information about it, you know, its properties and things.
And Mendeleev came in and said, “Well, I think you did those experiments wrong, because they didn't match my predictions of what I thought would happen.” And you can imagine the Frenchman took a little umbrage at this. That, you know, “I discovered it. You've never seen this stuff.” And then it turned out that Mendeleev was correct and the Frenchman had made mistakes with the research that he'd done.
Margot: Ah, sacré bleu!
Sam Kean: That's pretty impressive. It really showed people that the periodic table wasn't just a clever way to organize elements, that it had real predictive power and could really help us understand the properties of the elements and kind of how they fit together.
Margot: Right. Right. That's very cool. So while chemists are discovering all these new elements and developing the periodic table, I know they're also trying to make sense of how t chemicals work and how they come together and how they behave. What are some of the big discoveries that really change how people think about chemistry?
Sam Kean: So one big development was essentially disproving the ancient idea that there were four fundamental elements, uh, air, earth, water, and fire. The idea was still floating around from the ancient Greeks
So, uh, Lavoisier for instance was an aristocrat - very, very wealthy. He was involved in tax collecting in France before the revolution there, and a lot of people didn't like him because he was such a rich person.
Um, he ended up losing his head actually in the French Revolution, so he was actually executed because of his associations with the king in that regime. But he was a genuinely brilliant scientist.
He did a few things that were pretty important. Um, one thing is that he was able to decompose water into hydrogen and oxygen, that proved that water was not a fundamental element anymore, and that was really sort of the death nail of that whole ancient Greek system, was being able to break these things down and show that they weren't fundamental anymore.
So, he is the one who sort of, killed that theory off finally, so that was an important one. Another important one was conservation of mass.
Cathy Cobb: Lavoisier, this is something that he did very carefully. He burned a diamond by using a magnifying glass to get the focus of the sun. And he accounted for the fact that after he burned the diamond, he had carbon and this gas. And the masses equaled out.
Sam Kean: So it's basically chemical accounting in that, you know, you have a certain amount of stuff at the beginning and that stuff can change form. You know, a solid can go to a gas or a gas to a liquid. It can change shape, it could change color, odor, stuff like that.
But if you have a certain amount of stuff at the beginning, you have to have the same amount of stuff at the end. You don't magically make more of it. And if some of it magically disappears, then you probably have a leak in your equipment.
But as much as that, he was a good theoretical chemist, and he's the one who really figured out and sort of honed the idea of what an element is. And then everything around us is made of these individual elements combined in different ways.
Margot: Yeah, that seems pretty important.
Sam Kean: Yes. That's basically chemistry.
Margot: Haha. That’s basically chemistry. Yeah. So, then another big discovery, like what are elements made of, when did people start to understand chemistry at the atomic level?
Sam Kean: That really got going in the late 18 hundreds and then picked up in the early 19 hundreds. You had the discovery of things like electrons. And then you had people investigating atomic structure. So they're looking at the nucleus and figuring out how protons and electrons work together to make atoms. So there was a famous, uh, sort of debate whether an atom was like a star with a planet circling around it or whether it was what they called the “plum pudding model,” which is where there's a substance and then the electrons are sort of spread evenly throughout the way you would have raisins in a plum pudding. So yeah, so that was a debate that we're having - uh, what shape essentially and what form an atom took. And it was Rutherford really and his assistants, he was working with Bohr, especially, who figured out that it was more like a star with planets going around it than it was a solid mass, like a plum pudding with raisins, studded in it.
Margot: So, out with the pudding.
Sam Kean: Out with a pudding, in with the planet. Yep.
Margot: Yeah. And then, what did these new tools and this new Chemical knowledge do for chemists? Like how did it help them moving forward?
Sam Kean: So they could really do two things. One was investigate what things are made of. So the structures of them, very important for organic chemistry, things like that. Eventually though, they could also shift to making things. So to go less on the analytical side and more on the synthesis side, and use their knowledge of what things are made of to build new things that don't exist in the world naturally.
Cathy Cobb: because they had all these laws, they had all these elements, they had the periodic table, and they were able to put it together. And with the three dimensionality and the new theories of how the atom is formed, that kind of brings us to World War I with its entropy and ill-used energy.
OUTRO
Sam J: Entropy and ill-used energy - that is such a good way of describing war.
Margot: Right?
Sam J: Also, wow - we just zipped through history.
Margot: Yea we packed a lot in there and obviously left a lot out too.
Sam J: Lotsa content we didn’t touch that you will /absolutely/ hear about in future episodes.
Margot: Oh totally. I mean, we are literally just getting started here on Chain Reaction.
So, one of the things I took from this episode was that scientific progress generally seems to accelerate exponentially.
And Cathy really set us up nicely there - ending with World War 1. Because, up next, we are getting into the World Wars. It turns out, they have a lot to do with the investment in and modernization of chemistry.
Sam J: So I’d say this is the perfect time to ask our listeners to tune into the next episode in this miniseries.
Margot: Indeed it is Sam. And where we ask you, our listeners, to subscribe so you don’t miss new episodes!
ENDING CREDITS
Margot: This was Chain Reaction, a podcast by the American Chemical Society. Our executive producer is Sam Jones, our producer is me, Margot Wohl. Research was done by Bec Roldan. Fact checking by Michelle Boucher. Production help from Michael David and Matt Radcliff. Theme song by Dee Peterschmidt.
Sam J: And if you want to learn more about the work of everyone you heard in this episode, check out “The Secrets of Alchemy” by Larry Principe and Sam Kean’s latest book, “Dinner with King Tut”. Cathy Cobb wrote a book called “Creations of Fire; Magick, Mayhem, and Maverick” which details the full history of chemistry. Additional books from all of our guests are listed in our show notes. Check ‘em out!
Margot: Do you have a comment or question about the podcast? Email us at chainreaction@acs.org! We’d love to hear from you.
SHOW NOTES / REFERENCES
“The Secrets of Alchemy.” Larry Principe https://press.uchicago.edu/ucp/books/book/chicago/S/bo12335123.html
Fact or fiction?: Lead can be turned into gold, Scientific American https://www.scientificamerican.com/article/fact-or-fiction-lead-can-be-turned-into-gold/
Scientists turn lead into gold, Nature https://www.nature.com/articles/d41586-025-01501-5
The Chemical Revolution of Antoine-Laurent Lavoisier, ACS Historic Chemical Landmark https://www.acs.org/education/whatischemistry/landmarks/lavoisier.html
“The Disappearing Spoon.” Sam Kean https://samkean.com/books/the-disappearing-spoon/
All books by Sam Kean: https://samkean.com/books/
“Magick, Mayhem, and Mavericks.” Cathy Cobb https://www.simonandschuster.com/books/Magick-Mayhem-and-Mavericks/Cathy-Cobb/9781573929769
All books by Cathy Cobb: https://cobbfetterolf.wordpress.com/home/
Songs by Blue Dot Sessions used in this episode: “Helvetica”, “The Zeppelin”
