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  • Derek: The world is full of mysterious places

  • you can see from high above using Google Earth,

  • but what's really going on down there, and why?

  • I'm Derek Muller, a scientist, educator, and filmmaker,

  • and I'm going to unearth the stories

  • behind these amazing places.

  • Just drop a pin

  • and I'm off.

  • ( mysterious music )

  • ♪ ♪

  • I am here in the middle of the Utah desert

  • surrounded by sandstone cliffs and red rocks

  • and this scrub.

  • But that is not what I'm here for.

  • What I'm looking for should be right over this ridge.

  • ♪ ♪

  • There are electric blue ponds

  • in the middle of the Utah desert.

  • When I saw them on Google Earth,

  • I had so many questions, like what are they?

  • Why are they here?

  • And why do these colors keep changing?

  • One person thought this might be

  • a top-secret NASA experiment,

  • since, after all, you can see them from space.

  • Someone else suggested, "Well, maybe they're just really large swimming pools."

  • What are those? What do you think?

  • Like a geo kinda thermal thing? Like a solar thing?

  • Like, they come up from the ground?

  • It's gotta be some sort of, you know, science experiment of some kind.

  • They sort of look like rice paddies,

  • 'cause they're on ledges.

  • Derek: The truth is far more fascinating

  • than any of those guesses.

  • These technicolor pools are full of something

  • that's been prized throughout human history.

  • What are they used for

  • and how are they connected to fireworks,

  • George Washington, soap, glass, Gatorade, gunpowder,

  • a pioneering scientist named Humphry Davy,

  • every other person on the planet,

  • and lots of money?

  • ( birds crying )

  • ♪ ♪

  • The answer begins with a pot and a hardwood fire.

  • This is a 1,500-year-old recipe.

  • Take some hardwood and burn it,

  • not for the heat, but for the ash.

  • Put the ash in a pot and add water.

  • Now, there are a lot of different chemical compounds in there,

  • but the one I'm after is water soluble,

  • so it dissolves.

  • Strain out the solids and you'll find

  • the solution is slippery.

  • Put it in a pan and let the water evaporate in the sun,

  • and what you're left with is this crystalline substance.

  • All that work for this.

  • It is one of the most important chemicals

  • people have been making for centuries,

  • and it's called potash

  • because that is exactly where it comes from.

  • In 1807,

  • British scientist Humphry Davy got some damp potash

  • and put electrodes into it.

  • Then he connected them up to a battery,

  • and what he observed was the formation

  • of tiny metal globules,

  • and as they burst through the crust of the potash,

  • they spontaneously caught fire.

  • Davy had discovered a new element,

  • so naturally, he named it pot-ash-ium.

  • Potassium.

  • Yes, that is where the name of the element comes from.

  • It comes from the potash.

  • ♪ ♪

  • When you hear the word potassium,

  • many people think of bananas or Gatorade,

  • and that's true,

  • these foods are good sources of potassium,

  • but it's not pure potassium.

  • This is a piece of pure elemental potassium.

  • It's a metal, but I can squish it

  • with my fingers.

  • And this had to be created in a lab

  • because it is so reactive, it'll react with anything.

  • This piece was kept submerged under oil

  • so it doesn't react with the water in the atmosphere.

  • It's an incredibly reactive substance,

  • and to demonstrate that, I'm going to put a piece of it

  • in this water.

  • I'm gonna weight it down

  • so the potassium doesn't just sit on the top

  • but actually will sink down to the bottom.

  • Three, two, one.

  • - ( pops ) - Oh, yeah!

  • - ( pops ) - Oh!

  • - ( pops ) - Oh, yeah!

  • I did not expect it to do that.

  • That is awesome!

  • Are you kidding me?

  • Yeah!

  • Of course, I've seen this demo before,

  • but never with such a huge explosion.

  • ( in slow-motion ) Oh, yeah!

  • I think the key was weighing it down

  • so it didn't just spark on the surface.

  • Potassium reacts with water,

  • forming potassium hydroxide and hydrogen gas.

  • It also releases a lot of heat,

  • so when the hot hydrogen gas hits the atmosphere,

  • it spontaneously combusts.

  • Potassium is so reactive

  • because it has one electron in its outermost shell,

  • which is easily removed,

  • and that's why we never find metallic potassium in nature.

  • Now, the word potash originally referred to that stuff

  • which, chemically, is potassium carbonate,

  • but potash has become a catchall term

  • referring to lots of potassium-containing compounds.

  • So the potash that Davy was using

  • was actually potassium hydroxide.

  • And this is not the last time we're gonna hear from Davy.

  • But why is potash so important to people?

  • I'm on the trail of Potash.

  • Look at that.

  • ♪ ♪

  • All right.

  • This is bacon grease.

  • For centuries, it was used in making soap.

  • Take some animal fat, add potash,

  • and a chemical reaction creates a primitive liquid soap.

  • And look at that. This is incredible.

  • ( laughs )

  • I'm getting a real lather going here.

  • That's not bad. Take a look at that.

  • The potash soap actually worked.

  • Potash was also used to make glass.

  • Glass is mostly sand, silicon dioxide,

  • but add some potash

  • and you reduce the melting point.

  • This makes glass less brittle

  • and easier to work with in early furnaces.

  • ♪ ♪

  • ( Western music )

  • ♪ ♪

  • If you take the potash solution

  • and add bat guano or manure,

  • crystals of a different potassium compound form:

  • potassium nitrate, also called saltpeter,

  • and it's one of the core ingredients

  • in fireworks and gunpowder.

  • ♪ ♪

  • Get ready.

  • ( laughs ) That was awesome!

  • Saltpeter made from potash infused gunpowder

  • in the muskets and cannons

  • of battles fought in China, Europe,

  • and the American revolution.

  • ( slow-motion explosion )

  • Potash was by far the main chemical product

  • of the early American colonies

  • and a substantial source of revenue.

  • By 1788, there were 250 potash works

  • in the state of Massachusetts alone,

  • places where wood was burned on a massive scale

  • just for its ash.

  • In 1790, the newly-independent U.S. government issued

  • its first ever patent.

  • It was for an improved process for making potash.

  • The patent office has now issued over 10 million patents

  • and the literal first one is for potash.

  • It was signed on July 31, 1790.

  • Look closely at the signature.

  • It's signed by none other than President George Washington.

  • That should give you an idea of how important potash was.

  • The demand for potash was so high

  • that across Europe and the eastern U.S.,

  • forests were decimated.

  • Unfortunately, it required a huge amount of lumber

  • to create just a small quantity of potash.

  • Then in 1861 in Germany,

  • they started producing potassium

  • from a different source.

  • They found it not in plants or any living organism,

  • but in a rock.

  • This is potassium chloride

  • in its natural mineral form.

  • Now, this also gets the name potash

  • even though the name originally referred to ash in a pot, potassium carbonate.

  • It changed everything.

  • Germany established a near monopoly in the potash supply.

  • They had so much of the stuff that they started looking for new uses.

  • Well, they did experiments sprinkling this stuff on farmers' fields,

  • finding that this acts as an excellent fertilizer.

  • That's because potassium,

  • along with nitrogen and phosphorous,

  • help crops grow far larger

  • and makes them more drought-resistant.

  • The downside was, in 1910,

  • just four year before the start of World War I,

  • the Germans cut off potash exports to the world.

  • Their preemptive first strike

  • was depriving the world of potassium,

  • something countries had become dependent on

  • to feed their growing populations.

  • The U.S. became so desperate for other sources of potassium

  • that in 1911, Congress appropriated money

  • to find domestic sources.

  • Sites discovered near Searles Lake, California,

  • Carlsbad, New Mexico, and Moab, Utah,

  • became potash paydirt.

  • ( inquisitive music )

  • ♪ ♪

  • But the potash rocks weren't on the surface.

  • They were deep underground,

  • so potash had to be mined out.

  • ♪ ♪

  • But how did it get here in the first place?

  • I'm meeting Mike Coronella,

  • a Moab guide who knows the history of this area.

  • ♪ ♪

  • So the layer that the potash is found in

  • is called the Paradox Formation,

  • and it was created by an inland ocean

  • that kept retreating, returning,

  • retreating, and returning.

  • The water would evaporate and leave behind salt

  • and other evaporites like potash.

  • Salt in the ground is very much like an air bubble in water.

  • Geologically, it wants to float.

  • It's literally pushing up against the crust here.

  • And they used to harvest it underground

  • like coal, you know?

  • Scraping it out, throwing it on the narrow-gauge rail

  • up to the surface.

  • But salt also likes to trap oil and gas,

  • and there's oil and gas in this area.

  • And I believe it was 1963,

  • as they were mining the potash, they hit a pocket of gas

  • and there was a big explosion, major loss of life.

  • Derek: This tragic explosion occurred

  • at 4:40 in the afternoon

  • on August 27, 1963.

  • 18 men died.

  • Investigators concluded, the disaster was caused

  • by the ignition of combustible gas

  • by electric arcs, sparks, or an open flame.

  • Miners' electric tools or lights

  • or, back in the old days, candle flames

  • could ignite the natural gas, leading to huge explosions.

  • ( explosion pops )

  • But there was an invention made

  • to prevent such explosions,

  • an ingenious lamp.

  • This wire mesh disperses the heat from this flame