31. Gallium: Caught Wet-Handed

Meet one of the periodic table’s lesser-known liquid metals — and beware some dangerous competition from a few felonious element collectors.

Featured above: A certain 19th-century French chemist who may have been a little bit cocky.

Show Notes

This episode’s alternate title was, “The Wet Bandits.”

Credit Kean: The gallium gag is such a classic chemistry prank that author Sam Kean named his seminal book of elemental history, “The Disappearing Spoon.” It’s an excellent book, and I go out of my way to make sure these podcast episodes don’t just reiterate what he’s already documented.

I Thought There Were More Fools On The Internet: Here are a couple videos that demonstrate gallium’s “wetness” and mercury’s “dryness.”

Videos of mercury are shockingly uncommon on YouTube, but this is one where you can see how the metal acts when prodded with a glass instrument.

Creating that mirror is only possible because gallium adheres to the glass, i.e., it wets it.

But that’s actually an additional complication when it comes to the thermometers. By wetting the glass, the galinstan won’t rise and fall to accurately report the temperature. The interior needs to be coated with Teflon, or be made of gallium nitride, to ensure the thermometer will work. It’s a lot of effort to go through, but worth it to make sure kids don’t wind up mad as a hatter.

Be Prepared: The engineer and technician who saved the day at the SAGE facility might have been particularly vigilant because the facility had been hounded by the Russian government for months. They’d threatened to requisition the valuable metal to hand it over to the defense department. Is this connected to the attempted heist? Who can say?

But the gallium was already prized by sticky-fingered scientists. Earlier in the 90s, a small but noticeable amount of the metal “went missing” when scientists with few scruples started siphoning it off after hours. That actually wound up skewing some experiment results, and a few people did wind up in jail for that escapade.

Wrecka-Aluminum: When Mendeleev predicted the existence of gallium, he referred to it as “eka-aluminum,” borrowing a Sanskrit prefix to indicate that it was one order higher than aluminum on his periodic table. (i.e., gallium is directly below aluminum.)

Coincidentally, molten gallium will combine with aluminum to make it fantastically brittle. It’s quite a sight to see… so that means, naturally, more video:

I was kind of hoping to find a video of someone pouring gallium on a full can of soda, maybe after shaking it up a whole bunch. But I suppose the only people who use the internet are reasonable and risk-averse.

Episode Script

Gallium played an important role in the history of the periodic table — so important, that we discussed it in episode zero of this podcast. In case you’ve forgotten, Paul Emile Lecoq de Boisbaudran’s discovery of gallium helped confirm the validity of Dmitri Mendeleev’s periodic table. But there was another dust-up surrounding the announcement of element 31’s discovery — one around its name.

When de Boisbaudran first published his findings, he didn’t offer any explanation behind his choice to name the element “gallium,” leaving it open to speculation.1 His contemporaries concluded that he had slyly named it after himself: “Gallus” is the Latin word for “rooster,” AKA, a cock. As in, Paul-Emile Lecoq de Boisbaudran.

Now, chemistry has changed a great deal since 1875, but one thing that’s remained constant is how unimaginably gauche it would be to name a newly discovered element after one’s self. If de Boisbaudran had done such a thing, he at least had the good sense to deny it, explaining that he had named the element in honor of his home country, France, which was called “Gallia” in Latin.

It’s impossible to say how true that is, but for his part, de Boisbaudran stuck to his story for the rest of his life, vehemently denying that he had tried to install his own name in the annals of chemistry. But that almost doesn’t matter, because the tale is so compelling that it’s become an integral part of gallium’s etymology.2

You could say the story stuck to de Boisbaudran. And if you’re not careful, this mysterious metal might just stick to you, too.

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’ll get our hands on gallium.

Good news, everyone! We have finally made our way to the other side of the long corridor of transition metals, landing squarely upon an element that is categorized as a post-transition metal.

These are the elements that fall outside the confines of the periodic table’s d-block, the thick middle section that contains all the transition metals. The post-transition elements are usually subpar in at least one of their metallic qualities — ductility, malleability, conductivity, or reflectivity — but not so much that it puts their very nature into question, as with the metalloids.

Gallium is quite shiny, though on the spectrum of metallic qualities, it’s rather brittle and not a great conductor of heat or electricity. But I’m burying the lede here. Gallium’s most outstanding quality is one that’s best appreciated by the chemistry lab’s class clown.

The prank goes like this: You serve a colleague a hot cup o’ tea and provide them a gallium spoon to stir in their preferred amount of milk and sugar. Almost immediately, the spoon will dissolve in the tea, providing you with great mirth, and your colleague with some concern.

That happens because gallium’s melting point is around 85 degrees Fahrenheit, or 30 degrees Celsius. So given enough time, it will even pool in your hand, or lying out on a warm day.

Naturally, this behavior tends to draw comparisons to mercury, element 80, which is the most notorious of metals that are liquid at room temperature. But aside from their common state of matter, mercury and gallium could scarcely be more different.

First and foremost, while mercury can poison a person via ingestion, touch, or even inhalation, elemental gallium is entirely nontoxic. The victim of your prank might be especially eager to hear this information.

There’s another, less urgent difference between these two elements. Around room temperature, both metals can be liquid — but only gallium is wet.

That might sound odd. We’re pretty accustomed to thinking of liquids and wetness as being kind of synonymous. After all, water is a liquid, and it’s wet. So’s orange juice, and coffee, and motor oil, and bleach. What would a “dry liquid” even be?

Wetness, it turns out, is a liquid’s ability to adhere to another surface. So it’s technically more accurate to say that water can “wet” cotton, or skin, or glass — but not Teflon, or a duck’s back. Water will roll right off of those.

Mercury, however, will barely stick to anything. A drop of it won’t stain your blue jeans, it can’t be soaked up with a sponge, and it will nervously roll around inside a glass container without ever forming a puddle. That’s part of the reason it’s so fun to play with! …or so I hear from people who graduated high school a few decades before I did. The aforementioned toxicity has made mercury less popular as a classroom toy in recent years.

By contrast, gallium will wet just about anything. If you shake a glass jar with gallium inside, the interior surface of the jar will get entirely coated with shiny gallium, making it look like an antique mirror. If you let an ingot of gallium melt in your hands, you might later be surprised to find that your hands look pretty filthy, as if you’ve been handling coal, or printer toner.

So, when you’re adding gallium to your collection, you’ll want to consider wearing gloves — even if it won’t poison your brain.

Perhaps the most accessible source of gallium for the common collector is from glass thermometers, where element 31 has swept in to replace its metallic cousin. Along with classrooms, society has collectively decided that mercury probably doesn’t belong in sick people’s mouths, either.

It’s not that thermometers were responsible for widespread mercury poisoning or anything, but if the thermometer’s glass happened to break — as glass is occasionally wont to do — adding a liquid toxic heavy metal to the situation doesn’t exactly help.

But gallium didn’t make a perfect replacement for that application. Mercury remains liquid at temperatures well below zero, whether you’re measuring in Celsius or Fahrenheit, but elemental gallium needs a little help to remain liquid below 85 degrees Fahrenheit. Luckily, this isn’t hard to do. You might remember that compounds often have lower melting points than their constituent elements — in episode 19, we combined sodium and potassium to create an alloy that’s liquid at room temperature. We can employ the same trick here.

For this use, gallium is combined with two of its post-transition neighbors, indium and tin, in an alloy called “galinstan.” If you can guess why it has that name rather than “galintin,” leave a comment at episodic table dot com slash G A for five points extra credit.

You can leave your thermometer intact if you happen to own a Blu-ray player, because gallium is an important part of the light-emitting diode that gives that device its colorful name. Blue LEDs are actually a relatively recent invention, which took many scientists by surprise. For a long time, scientists couldn’t figure out how to build blue LEDs or lasers. Gallium turned out to be the secret ingredient.3

Of course, none of these possibilities will satisfy the discerning collector. For those of you, I have good news and bad news. The good news is, I know of a place that houses 60 metric tons of lab-grade gallium. The bad news is, even a crack team of criminals couldn’t get a hold of it.

Let me back up a bit.

There’s far more to the world of subatomic particles than the protons, neutrons, and electrons we typically deal with on this podcast — and they can have some truly mind-bending qualities.

Take the neutrino.4 It’s a kind of particle that’s created by radioactive decay, and it’s very, very, very small. For a long time, scientists thought that it had a mass of zero — but it turns out to have less than one millionth the mass of an electron. It’s like comparing the size of an ant to the size of Atlanta — if Atlanta were already incomprehensibly tiny.

Mass is not the only factor making neutrinos difficult to find. Unlike, say, a photon, neutrinos barely interact with anything. The sun sends billions of them flying toward Earth every second — and the neutrinos pass straight through our planet as though it were nothing at all.

One of the few things neutrinos will occasionally interact with is gallium. Occasionally, a neutrino will strike a gallium atom in just the right way, changing it into a radioactive isotope of germanium.

Of course, this is still an exceptionally rare event. If scientists want to observe this on a regular basis, they really need to stack the odds. They can’t change the sun’s neutrino output… but they can gather a lot of gallium in one place, and regularly measure how much of it has turned into germanium.

That’s the premise behind SAGE, the Russian-American Gallium Experiment. Three-and-a-half kilometers below the Caucasus mountains, this study been running for thirty years.5 6 (It retains an acronym that implies “Soviet,” presumably because no one wants to change the acronym to RAGE.) There, enormous tanks are filled with pure liquid gallium. And that holds considerable appeal, not only because it would make a fine sample for one’s element collection — it’s also worth hundreds of dollars per kilogram.

That’s why, In October 1997, this underground laboratory in the Russian countryside became the target of an elaborate heist.7

It was a well planned operation carried out by six masked men under cover of darkness. Before anything else, they severed every communications cable that connected the lab to the outside world. Then they leapt into action. Wielding two machine guns, the chemical criminals took a forklift driver hostage and commandeered his vehicle. The gang clearly had inside knowledge, because they made a beeline for the precise location where the gallium was stored.8

Their timing was pretty good, too. It was late one night on the weekend, so there were only two unfortunate souls in the lab, an engineer and a technician.

It turns out, those two were pretty sharp, too. As soon as they heard the commotion, they locked down the facility, locking every door and killing the lights.

The thieves hadn’t quite been counting on that little hiccup. When they got to the first door, they sent their forklift driver-hostage ahead, trusting that he would have the security clearance to open it. He did not, so the thieves turned to brute force instead. They broke down that first door by hand, but they dealt with additional ones by ramming them with the forklift at top speed.

The tech and engineer hurried to hide the precious gallium as best as anyone can hide sixty tons of liquid metal, but they didn’t want to stick around. So they ducked inside a ventilation shaft, John McClane-style, and clambered out of the lab.

Whatever they did to disguise the gallium worked. The thieves knew they needed to work quickly, but breaking down barred doors with a forklift truck is a time-consuming process. After ransacking several rooms with nothing to show, the crooks fled the scene just before the authorities arrived, all thanks to the quick thinking of two scientists who got stuck with the weekend’s graveyard shift.

Why on earth might sixty tons of gallium have been the target for such a caper? It’s hard to say, because the criminals behind the act were never caught, but it seems unlikely that they would’ve sold it off to the world’s thermometer manufacturers.9 Gallium nitride in particular is useful as a high-tech semiconductor, which can, for instance, help detect stealth aircraft at a long range. Any entity pursuing that sort of end seems like they wouldn’t have any reservations employing such unorthodox means.10

So stay safe out there, all you discerning collectors, and remember: Sometimes your competitors’ motives aren’t as pure as the elements they seek.

Thanks for listening to The Episodic Table of Elements. Music is by Kai Engel. Special thanks to Consulting Producer Derrick Burton for his help finding credible sources with details about the gallium robbery. To learn who was successful in stealing gallium from the SAGE laboratory, and see why you don’t want to keep your sample in an aluminum container, visit episodic table dot com slash G A.

Next time, we’ll continue our tour of the European continent with germanium.

Until then, this is T. R. Appleton, reminding you that the more you tighten your grip, the more gallium will slip through your fingers.


  1. The Annals Of Chemistry, About A New Metal, Gallium. P.E. Lecoq de Boisbaudran, 1887.
  2. Elementymology & Elements Multidict, Gallium. Peter van der Krogt, 1999 – 2010.
  3. The Verge, Gallium Nitride Is The Silicon Of The Future. Angela Chen, November 1, 2018.
  4. Please!
  5. Spaceship Neutrino, p. 170. Christine Sutton, 1992.
  6. Measurement Of The Solar Neutrino Capture Rate With Gallium Metal, April 29, 1999.
  7. Science, Thieves Bedevil U.S.-Russian Neutrino Detector. Science News Staff, November 12, 1997.
  8. Science, Thieves Target 60-Ton Neutrino Detector. Andrew Allakhverdov, Vladimir Pokrovsky, November 14, 1997. Unfortunately, this paper requires login credentials to read, and I’m not able to find a more public source.
  9. The New York Times, A Detector’s Rare Metal Faces Seizure In Russia. Malcolm W. Browne, January 20, 1998.
  10. Breaking Defense, The Biggest Thing Since Silicon: Raytheon’s Gallium Nitride Breakthrough. Sydney J. Freedberg, Jr., February 20, 2015.

2 Replies to “31. Gallium: Caught Wet-Handed”

    1. Five points! 🙂 And as I’m sure you know, that’s why tin’s chemical symbol is Sn. (As we mentioned in the Titanium episode, TiN is titanium nitride. It all makes complete sense and isn’t confusing at all.)

      Thanks for commenting!

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