58. Cerium: Light My Fire

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It’s the most common flint you’ll find, except it’s not actually flint at all.

Featured above: Ferrocerium in action.

Show Notes

You might think that while we’re all stuck at home, I might be able to dedicate more time to the podcast. Unfortunately the opposite has been true! I’ve found myself busier than ever lately.

So yet again, I’m posting the episode now and will have show notes and sources added within a day or two. My apologies for the inconvenience!

Episode Script

August 24, 2006 might be the most scandalous day in the history of popular science. That was the day the International Astronomical Union ended a decades-long debate. In order for an object to be a planet, it must meet three criteria: It must be in orbit around the Sun; it must have enough gravity to result in a nearly spherical shape; and it must have “cleared its neighborhood” of orbital debris. That’s all well and good, except, by this new definition, Pluto could no longer be considered a planet.^{1 2 3}

Mike Brown, an astronomer from CalTech, pulled no punches when breaking the news. “There are finally, officially, eight planets in the solar system,” he said. “Pluto is dead.”

That might be just a touch dramatic. Pluto isn’t exactly dead. Rather, it became the first of a new class of objects: Dwarf planets. These are bodies that fall just short of the bar for planetary status; that is, they haven’t cleared their neighborhood. Much of the astronomy community was relieved by the move, because if Pluto were a planet, dozens of recently discovered Pluto-like objects would also have to be classified as planets.

But the general public didn’t care how well reasoned this decision was. This was scandalous! Those poindexters over at NASA were bullying plucky little Pluto out of the Planet Club! Pluto didn’t do anything wrong! What would My Very Educated Mother Just Serve Us Nine of, now? Such an unthinkable act of astronomical humiliation was unprecedented!

Except… well, it wasn’t unprecedented. Ceres is the largest object in the asteroid belt. It’s much smaller than Earth’s moon, but still massive, and satisfyingly spherical. Upon its discovery on the first day of the nineteenth century, people counted it among the solar system’s planets. The smallest planet, perhaps, but a planet nonetheless.^{4 5 6 7 8}

The following year, when Pallas was discovered, it too was added to the roster of planets. In 1804, they were joined by Juno. And then Vesta, and Astraea, Iris, Flora, Hygiea… By 1851, it was clear that a distinction needed to be drawn between these minor curiosities and the more significant planets. So these smaller bodies became known as “asteroids” — including Ceres, the first asteroid that was discovered. It was practically the same thing that would happen to Pluto one hundred fifty-five years later! Formerly one of the few major objects in our solar neighborhood, Ceres was now one among hundreds, something less valuable.⁹

But there is something the largest asteroid still shares with the rest of the planets. Only two years after Giuseppe Piazzi discovered Ceres, Berzelius and friends discovered a new chemical element here on earth. They named the element cerium in honor of the landmark astronomical discovery — placing it in the company of other elements named after planets, like mercury, tellurium, and neptunium.¹⁰

Regardless of what the stargazers behind their telescopes had to say, Ceres had undeniably secured its place in chemistry’s official record of noteworthy entities. And that’s a distinction that no one is going to take away.

You’re listening to The Episodic Table Of Elements, and I’m T. R. Appleton. Each episode, we take a look at the fascinating true stories behind one element on the periodic table.

Today, we’re shedding a little light on cerium.

In the year 1803, cerium became the first rare earth metal to be discovered. That was always the way it was likely to go down, since cerium is also, by far, the most abundant of the rare earth metals. In fact, it’s so abundant that it was discovered twice that year: Once in Sweden, by Jons Jacob Berzelius and Wilhelm von Hisinger, and coincidentally around the same time by Martin Heinrich Klaproth in Germany.¹¹

It was yet another case, as we’ve highlighted before, of multiple discovery. Sometimes, in the scientific realm, the light bulb goes off for more than one person at the same time.

That imagery of a light bulb illustrating an epiphany is, well, brilliant. Light is a pretty universal symbol of knowledge, from Buddhism to Plato’s Republic.¹² But unlike the sun, a light bulb provides the full power of its illumination immediately and is itself one of humanity’s bright ideas.

In fact, a lot of what we said back in Caesium’s episode about timekeeping devices goes hand-in-hand with advances in artificial lighting that cropped up around the same time. At least as revolutionary as the electric bulb was gaslight.^{13 14 15}

While lamps have been around for tens of thousands of years, they were strictly personal technology, providing just enough light to talk to the bedroom or study a manuscript. It wasn’t until 1792 that city streets could be brightly and reliably lit at night, when William Murdoch installed pipes carrying coal gas to lamps all over his house and the foundry where he happened to be employed by legendary Scottish scientist James Watt.

Now workers could labor in factories around the newly invented clock, no matter whether it was day or night. The streets after sunset were no longer the sole domain of criminals.¹⁶

And coal gas provided the first application of another new technology: Networks. Before the railroad and the telegraph, homes and streets became physically linked by a series of pipes carrying the incandescent fuel governing the new social rhythms. And a vital aspect of home life fell under the direct control of either the local government or a corporate monopoly.^{17 18}

Carl Auer von Welsbach was a disciple of none other than Robert Bunsen, held in such high esteem that he was awarded his PhD without even submitting a thesis. He improved upon the gas lamp by hanging within the flame a mesh made of ninety-nine parts thorium to one part cerium. He found that this mixture provides a lot of light in the visible spectrum, whereas existing technologies inefficiently emitted energy as invisible infrared light.^{19 20}

Combining this superior technology with a dramatic flair for salesmanship, von Welsbach became wildly successful, selling over 300 million such lamps by 1913. He accumulated enough wealth to build his own castle, complete with a private chemistry lab. Not one to rest on his laurels, he continued advancing the technology of light, becoming one of the dozens of scientists who ensured the practical and commercial success of the electric bulb that would eventually render his prior invention obsolete.²¹

Electric lighting was a crowded field in which Thomas Edison most notoriously won the battle for publicity, but von Welsbach earned more exclusive success with yet another cerium-based technology: Flint, of the kind used in cigarette lighters.

At least, it’s commonly called flint, but that’s something of a misnomer. After all, nobody “invented” real flint — some of the earliest humans on earth found it on the ground and used it to start fires. True flint is a type of quartz, a mineral composed of silicon and oxygen. What von Welsbach invented was a mixture of iron and cerium that could generate extremely hot sparks, even when wet, and was very cheap to produce.

This, rather than his version of the light bulb or the gas mantle, would be Carl Auer von Welsbach’s most enduring contribution to chemistry. It was also this invention, a few decades later, that allowed one talented chemist to endure.

We last mentioned Primo Levi way back in episode 30, because he suggested that zinc is “a boring element.” There’s much more to his story, though.^{22 23}

He was a shy and frequently ill boy, often bullied for being Jewish. He came of age under Benito Mussolini’s fascist Italy, and in 1944 was shoved in a cattle car and sent to Auschwitz.²⁴

There he had the debatably good fortune to be conscripted to work as a chemical engineer in a synthetic rubber factory. Access to a laboratory allowed him to perform experiments in survival. He tried eating burnt cotton and drinking glycerin, but found that the raw calories they provided were not worth the side effects induced. He had more success with a sludge made of paraffin that “really took the edge off” his hunger.

But it was an unlabeled jar of small, grey, metallic sticks that proved most useful to Levi. After a bit of study, he and a friend deduced that these were stick of ferrocerium, the same compound von Welsbach used as his so-called “flint.”

Other prisoners in the camp could use this material in the creation of contraband cigarette lighters — a valuable commodity. So in the chaos caused one day by an air raid siren, Levi swiftly pocketed all forty sticks of cerium. It was enough to purchase two months of bread — two months of life — for both him and his accomplice.

That made all the difference, because two months later, the Russian Army finally arrived and liberated Auschwitz.

Familiarity with the behavior of one obscure element saved Levi’s life, and allowed him to go on to share that knowledge with millions of students of chemistry — now including you among their number.

You will likely not make much headway in your search for cerium if you just poke around unlabeled jars in the nearest chem lab — but of course, you don’t need to. Many lighters continue to use Carl Auer von Welsbach’s ferrocerium “flint” to this day. Just make sure it’s not one of those lighters that generates a little electrical spark instead. Ironically, those “flint-less” lighters actually use a bit of quartz to generate that spark, so they’re closer in origin to true flint than the stuff we’re looking for.

You might already have a little cerium in your home if you have one of those fancy self-cleaning ovens. The interior walls of those appliances are usually coated in cerium oxide, which helps any food particles easily turn to ash. You do still need to wipe those ashes up, though, so they’re not exactly self-cleaning.

Yet for all of element 58’s pyrophoric tendencies, it has one quality that seems quite contradictory: a topical solution of cerium nitrate can help to soothe severe burns.

It’s the kind of fact we bump into pretty regularly on the periodic table, and thank goodness. After all, we wouldn’t want to take things too seriously.

Thanks for listening to The Episodic Table of Elements. Music is by Kai Engel. To learn how Ceres became part of a complete breakfast, visit episodic table dot com slash C e.

I’m especially grateful to those of you who have taken the time to send a kind email or write a review of the show on Apple Podcasts. It’s incredibly rewarding to hear what so many of you think of the show, and every rating, review, and recommendation helps more people discover the show. Thank you!

Next time, we’ll get knocked out of the spelling bee with praseodymium.²⁵

Until then, this is T. R. Appleton, reminding you

One fire drives out one fire; one nail, one nail;

Rights by rights falter, strengths by strengths do fail.

1. Space.com, Pluto No Longer Considered A Planet In Highly Controversial Definition. Robert Roy Britt, August 24, 2006.
2. EarthSky, This Date In Science: Pluto Gets A Demotion. Jorge Salazar, August 24, 2013.
3. Library Of Congress Everyday Mysteries, Why Is Pluto No Longer A Planet?
4. BBC Bizarre Cosmic Objects, Ceres: The Planet That Wasn’t. Marcus Woo, August 28, 2015.
5. Dawn Of Small Worlds: Dwarf Planets, Asteroids, Comets, p. 200-202. Michael Moltenbrey, 2015.
6. NASA Science Solar System Exploration: Ceres.
7. SAO/NASA Astrophysics Data System (ADS), How The First Dwarf Planet Became The Asteroid Ceres. Clifford J. Cunningham et. al., 2009.
8. Vice, The 19th Century Space Controversy That Sparked A Planet Truther Movement. Becky Ferreira, January 1, 2016.
9. Space.com, Who Really Invented The World ‘Asteroid’ For Space Rocks? Mike Wall, January 10, 2011.
10. Giuseppe Piazzi And The Discovery Of Ceres, G. Fodera Serio et. al.,
11. Chemicool, Cerium Element Facts/Chemistry. October 3, 2012.
12. Notopoulos, J. A. (1944). The Symbolism of the Sun and Light in the Republic of Plato. I. Classical Philology, 39(3), 163–172. doi:10.1086/362816
13. The Independent, Artificial Light: How Man-Made Brightness Has Changed The Way We Live And See Forever. Jane Brox, May 12, 2011.
14. Wired, A Brief History Of Light. Betsy Mason and Keith Axline, December 25, 2008.
15. Pop Matters, ‘Brilliant’ Tells The History Of Artificial Light And How It Has Changed Who We Are. George Russell, October 18, 2010.
16. The Guardian, Life Before Artificial Light. Jon Henley, October 31, 2009.
17. City: A Guidebook For The Urban Age, p. 297. P.D. Smith, 2012.
18. Privatization, Restructuring, And Regulation Of Network Utilities, p. 19-21. David M. Newberry, 2002.
19. Stock, J. T. (1991). Carl Auer von Welsbach and the development of incandescent gas lighting. Journal of Chemical Education, 68(10), 801. doi:10.1021/ed068p801
20. Encyclopedia Britannica, Carl Auer, Freiherr von Welsbach. Last updated August 28, 2019.
21. Chemistry World, Auer’s Lamp. Andrea Sella, September 22, 2015.
22. The Periodic Table, p. 142-149. Primo Levi, 1975.
23. Cerium, forward by Carole Angier.
24. Encyclopedia Britannica, Primo Levi. Last updated December 18, 2019.
25. Ha! I actually spelled it correctly without checking, first try!