7 Mad Science Experiments You Can Do At Home But Probably Shouldn’t

Posted in Science and Technology on Feb 13, 2010 at 7:33 am

By the time you finish reading this article, you will undoubtedly think of Theo Gray when you hear someone say "mad scientist."

Theo, a columnist for the magazine Popular Science, recently published a book titled Theo Gray’s Mad Science: Experiments You Can Do At Home – But Probably Shouldn’t. The book is full of experiments so outrageous (Ignite your own phosphorus sun in a globe filled with pure oxygen! Make your own shotgun ammo by pouring molten lead off the roof! Heat a hot tub with 500 pounds of quicklime!) that it sounds like a parent’s nightmare. It’s actually quite the opposite: there’s no a better way to spark the imagination of the young minds of proto-scientists than to bring science to life with Theo’s hands-on experiments. Yes, these are dangerous experiments but that’s why they’re so much fun!

Behind the gorgeous photos of each experiment, there is solid science explained in clear, accessible language with a little dash of humor that made Theo’s monthly PopSci column so popular. You’ll see. Let’s dive into the excerpts of the Mad Science book. Here’s Neatorama’s premiere Spotlight article, 7 Mad Science Experiments You Can Do At Home But Probably Shouldn’t, by Theo Gray …

1. Gag with a Spoon: The Melting Spoon Prank

DISAPPEARING ACT - A steaming cup of water liquefies the spoon in about 15 seconds - notice the puddle at the bottom of the cup. Photo: Jeff Sciortino.

With the right mix of metals, you can make an alloy that turns to liquid at nearly any temperature.

Mention liquid metal, and people immediately think of mercury. After all, it is the only metal that isn't solid at room temperature. Well, not quite - it's the only pure metal, but there are many alloys (mixtures of metals) that will melt well below that point. For example, the mercury-filled fever thermometers that children were told not to play with in the 1950s and '60s have been replaced by virtually identical ones containing the far less toxic Galinstan, a patented liquid alloy of gallium, indium and tin.

Those who were kids in that era may also remember playing with another low-melting-point alloy: trick spoons that melted when you tried to stir your coffee with them. These were made with a blend that, no surprise, was highly toxic; it typically contained cadmium, lead, mercury or all three. But, as it happens, it's possible to make alloys that liquefy in a hot drink using safer components.

A few months ago I created a batch of these prank spoons as a gift for my friend and fellow element buff Oliver Sacks (author of Awakenings and Uncle Tungsten). I cast jewelers' molding rubber around a fancy spoon to form the mold. Then I looked up the formula for an alloy that would melt at 140 °F, roughly the temperature of a cup of hot coffee, and found this one: 51 percent indium, 32.5 percent bismuth and 16.5 percent tin.

After the spoon turns to a puddle at the bottom of the cup, you can pour off the liquid and touch the metal, feeling the weird sensation of it hardening around your fingertip. When Sacks has used up all his spoons, he can easily recover the metal, melt it again over a cup of hot water, pour it into the mold, and make new ones - the trick-spoon circle of life.

So why can't you buy these nontoxic prank utensils in toy stores, as you could the toxic versions of years past? Price. Indium costs about three times as much as silver. (I get mine from a bulk supplier in China.) Using gallium, you can make alloys that melt in lukewarm water or even in your hand, but it's more expensive than indium, and it tends to stain the glass and discolor skin. Unfortunately, no alloy replicates the low cost, bright shine and nonstick fun of mercury. Too bad we know now that playing with it for too long can give you brain damage.

2. Calling Van Helsing: How to Build Your Own Werewolf Killers

BULLET PARTS - [from left] Bullion bars and rounds, the cheapest source of pure silver; the graphite mold, opened after casting a bullet; the profile bit used to machine the mold; silver bullets as cast and polished to a mirror finish. Photo: Mike Walker.

(L) TURNING THE BIT - Using a lathe to create the milling bit that will be used to make the graphite mold. (R) LIQUID METAL - Molten silver at 1,800 °F pours into a graphite bullet mold from an electric jewelers' melting cup. Photos: Mike Walker.

Suss the myth from the reality with a hands-on investigation into the original anti-werewolf weapon.

Like darning socks, making bullets is a dying art. Used to be just about everyone with a need for ammo poured their own, using iron or even wooden molds. These days only a few diehard hobbyists still do it, and they use aluminum molds. But even fewer people still make silver bullets.

Actually, not many people ever made silver bullets. It's a difficult process, and their efficacy against werewolves has never been scientifically proven. I suppose their renown came from the perception that silver was a distinguished metal, often spoken of in connection with its higher class cousin, gold. But today silver is far more common, and it tarnishes over time, primarily because of sulfur pollution from power plants. (By and large, it didn't tarnish before the Industrial Age.)

I couldn't find any references describing real historical silver-bullet-crafting techniques. At 1,764 °F, molten silver would ruin traditional and modern bullet molds. They could have been fashioned using jewelers' methods, but that would require a new plaster mold for every bullet. Frankly, I think people spent a lot more time talking about silver bullets than they did turning them out.

I don't like legends that are all talk, so I decided to see what it takes to produce a real silver bullet: not plated, not sterling - pure silver.

To create the mold, I first had to construct a bit. I used a lathe to turn a steel rod into a bullet-like shape, then used a milling machine to cut away a quarter-circle wedge of the rod, leaving a sharp cutting edge. Basically I had built a router bit shaped like a bullet. (I've fabricated bits like this freehand with a file, which works fine; it just takes longer. Much longer.)

After using the bit to machine the graphite bullet mold, I used an electrically heated graphite crucible to pour in the 0.999 fine liquid silver at about 2,000 °F, which is 230 °F above its melting point. The mold must be preheated with a blowtorch to keep the silver from solidifying before it fills the whole cavity. One of the benefits of using graphite is that it keeps the silver from oxidizing, so bullets come out bright and shiny.

Would a silver bullet really fire? Probably. (Though, not being an experienced gunsmith, I would never be foolish enough to try my bullets in a real gun.) Bullets need to be fairly soft so that they can take on the shape of spiral grooves in the gun's barrel, and pure silver is moderately soft. It's also similar in density to lead, so it should have similar aerodynamics and muzzle velocity. I'd guess silver would make a very nice nontoxic substitute for lead in bullets. Too bad about the cost: These one-ounce, large-caliber rifle bullets use about $12 worth of silver per shot - best reserved for only the most severe werewolf infestations.

3. Build Your Own Lightbulb

A VERY BIG BULB - The stick welder [left] provides enough juice to heat a tungsten rod to nearly 5,000 °F. The ice bucket acts as the bulb, and the helium displaces oxygen. Photo: Mike Walker.

Act as if you're smarter than Edison: Construct a lightbulb the modern way with some helium and an old welder.

Thomas Edison famously spent months trying to make a lightbulb work. He tested one material after another in an evacuated bell jar before he finally got a carbon filament to burn long enough to sell it with a straight face. When I had a free afternoon recently, I thought I'd see if I could do it too.

Edison's first mistake was living before tungsten wire was available. Tungsten is way better than carbon as a filament material, and now you can find it in any metal-supply shop. It lasts longer, is less brittle, and glows with a cleaner, whiter light. His second mistake, repeated in classroom physics demonstrations to this day, was using a vacuum to get the air out of the bulb. Clearing out the air is important because at yellow to white heat (3,500 °F to 5,000 °F), pretty much all known materials, even tungsten filament wire, react with oxygen and burn up in a few seconds. Remove the oxygen, and the wire can't burn. But a vacuum is the hard way to solve that problem. You need an expensive vacuum pump, a thick glass bell jar to withstand the pressure of the surrounding atmosphere, and several nonleaking pipe joints.

It's a whole lot easier to just displace the air with an inert gas that's at the same pressure as the surrounding air, which is how most modern bulbs work. Common household lightbulbs use a mixture of argon and nitrogen. Fancy krypton flashlights and xenon headlamps use those eponymous heavier noble gases to allow the filament to burn longer and hotter.

I used helium because it's easily available and lighter than air, allowing me to fill my bulb, an upside down glass ice bucket (wedding present, I believe), from the bottom. The helium floated up, displacing the air inside. With a steady stream flowing in, I didn't even need to seal the bucket very well - I just wrapped a sheet of tinfoil over the bottom to keep eddies of air from wafting in.

For a filament, I used a thick tungsten wire I had lying around the shop and, for the power supply, a small stick welder I got at an auction. It supplied about 50 amps at 30 volts, giving me a 1,500 watt bulb. When I powered up the filament without the bucket in place, it produced a prodigious quantity of tungsten-oxide smoke and didn't last very long. But with the bucket on and a steady flow of helium, the filament glowed brightly and cleanly.

It must have been truly thrilling for Edison when he finally got one of these things to work for the first time. I know I was thrilled, even though I slaved over mine for only about 30 minutes and it worked perfectly the first time - well, the first time I didn't forget to turn on the helium.

4. Making a Deadly Sun

ONE BAD BALL - A white phosphorus 'sun'. The smoke is phosphorus pentoxide. Photo: Mike Walker.

HUNK O' BURNING SUN - White phosphorus burning in air glows with a phosphorescent beauty. Photo: Mike Walker.

(1) Suspend the white phosphorus in the center of a lobe filled with pure oxygen. (2) The burning phosphorus rapidly fills the globe with thick white smoke. (3) The chip of phosphorus burns energetically for more than a minute. (4) CLOUDY SUN - It takes about a minute for the phosphorus to burn itself up, leaving only smoke. Photo: Mike Walker.

From urine to firebombs - white phosphorus is among the nastiest of elements.

In 1669 the pompous German alchemist Hennig Brandt accidentally discovered white phosphorus while boiling urine in Hamburg. He became the talk of the town by demonstrating its amazing luminous powers to scientists and dignitaries.

In a cruel irony, 274 years later the discovery he'd hoped would turn lead into gold instead turned his city to ashes when a thousand tons of white-phosphorus incendiary bombs created one of the great firestorms of World War II; 37,000 people died when the sky burned over Hamburg. Yet even today, white phosphorus is still used as a weapon.

I've used red phosphorus to make a batch of kitchen matches. Although both red and white phosphorus contain nothing but the pure element, red is mostly harmless on its own, whereas white is near the top in every category of dangerous. It'll ignite spontaneously and burn vigorously until you deprive it of oxygen. One tenth of a gram inhaled is fatal, and smaller doses over time can make your jaw fall off (seriously - it's called phossy jaw).

The difference is that white phosphorus is a waxy paste consisting of highly strained atoms bound into tetrahedrons. The energy in their chemical bonds is bursting to get out, causing white's high reactivity. The atoms of red phosphorus are linked in relatively stable chains. Same element, very different properties.

Brandt was trying to turn lead into gold, and finding a substance that glows in the dark seemed like a big step in the right direction. Of course, it wasn't, and he died poor after spending two wives' fortunes on boiled urine. (Alchemists were obsessed with urine because it's yellow and they were trying to make gold. Transmuting lead into gold is possible, but it turns out you need a nuclear reactor, not buckets of pee.)

Still, the discovery of white phosphorus was an important one in early chemistry. These days it is used in many ways, including the phosphoric acid in nearly all colas. It's also used in a particularly beautiful classroom demonstration of its extreme flammability and brilliant yellow light. Just hope you never see that light in your neighborhood.

5. Trap Lightning in a Block

[YouTube Clip]

Freeze a charge screaming through solid plastic - or printer toner - to see how electricity moves.

There are many unusual things to see around Newton Falls, Ohio - the Wal-Mart with hitching posts for Amish buggies, the Army base with helicopters and tanks proudly arranged on hills - but I was here for the most unusual thing of all: the local Dynamitron. I was here to make frozen lightning.

The Kent State Neo Beam facility's Dynamitron is a four-story-tall, five-million-volt particle accelerator much like a tube TV, only bigger (Yes, tube TVs are domestic particle accelerators.) Both Dynamitrons and TVs use high voltages and magnets to slam electrons into a target. In a TV, that's the phosphor screen; in this Dynamitron, it's usually plastic plumbing components being hardened by the beam. But when I joined the team of retired electrical engineer Bert Hickman and physicists Bill Hathaway and Kim Goins, the product was Lichtenberg figures, lightning bolts permanently recorded in a block of clear acrylic.

With the Dynamitron - rented for the day - adjusted to around three million volts, it blasts electrons about halfway through half-inch-thick pieces of acrylic sheet. The plastic is a very good insulator, so it traps the electrons inside. Coming out of the machine, the blocks don't look any different, but they hold a hornet's nest of electrons desperate to get out.

Left alone, the electrons will stay trapped for hours, but a knock with a sharp point opens a path for them to make a quick escape. Electrons gather from all parts of the block, joining up to form larger and larger streams of electric current on their way toward the exit point. As the charge leaves, it heats up and damages the plastic along the branching trails it follows, leaving a permanent trace of its path. If you could see inside a thundercloud in the nanoseconds before a bolt of lightning emerged, you would see the same kind of pattern. The bolt doesn't just pop up fully formed; it has to gather charge from all over the cloud.

You can create similar, if less permanent Lichtenberg figures using toner powder from a copier or printer and any common source of static electricity. This is how German scientist Georg Christoph Lichtenberg first did it in the late 18th century (he used powdered sulfur), which at the time represented one of the great discoveries in the history of electricity. Today, the figures are a great way to learn about electrical discharge - and can make a cool souvenir from an afternoon with a very expensive machine.

6. Nickel Growing in Trees

WASTE NUT - These nodules of chrome and nickel build up over time from the process of electroplating bumpers. Photo: Chuck Shotwell.

Electroplating uses electricity to turn dissolved ions into a thin layer of solid metal bonded to a surface. Photo: Chuck Shotwell.

Electroplating makes bumpers shiny and rustproof. It also makes these beautiful bits of industrial waste.

If there were a contest for most attractive industrial waste, these nickel-chromium nodules would win hands-down. As intricate as the veins on a leaf, brighter than a '57 Chevy in the noonday sun, they grow naturally in tanks of chemicals simmering gently in a bumper factory somewhere in the Midwest. Eventually workers whack them off with hammers and dump them in barrels for recycling.

Bumpers are stamped out of steel and elecroplated with a thousandth of an inch of nickel (for rustproofing) followed by 65 billionths of an inch of mirror-bright chromium (for shine). Everything you see is chromium, yet it represents no more than a millionth the weight of the bumper.

Electroplating uses electricity to turn dissolved ions into solid metal bonded to a surface. Bumpers sit in a vat of acid containing dissolved, positively charged nickel ions. A current is run through the solution, forcing negatively charged electrons from the bumper into each nickel ion, neutralizing it. The ions bond to the bumper, plating it with a very thin layer of solid metal. After the nickel is applied, robot cranes transfer the bumpers to tanks of chromic acid, where the same process adds a coating of chrome.

Titanium bolts and T-shaped wing nuts attach the bumpers to titanium frames carrying about 10,000 amps at around three volts. The bolts, nuts and frames are coated with rubber-like insulation, but it's never perfect. Tiny cracks and nicks form over time, allowing electrons to escape and the metal to start depositing. Bumpers go through the line only once, but the frames and T-nuts are dipped repeatedly. Over dozens of chrome and nickel baths, these wonderful nodules build up.

In a week, the factory I visited turns tons of nickel and chrome into thousands of gleaming beauties. It also makes about 10,000 bumpers.

Official webpage: Nickel Growing in Trees

7. Shattering the Strongest Glass

[YouTube Clip]

SHATTERED GLASS - A piece of tempered glass shatters all over from a blow to one corner.

Explosive glass drops demonstrate why your car windshield is so strong and safe.

If you want a scientific display of the dangers of pent-up stress, Prince Rupert's drops are it. After the trauma of being dropped molten-hot into a bucket of cold water, these glass balls, named for a 17th-century amateur scientist, turn into bundles of high tension. They're impervious to even the strongest blows, until you find their hot button: Flick the tail, and they explode.

When molten glass hits cold water, its outer surface cools rapidly and shrinks as it solidifies. Since the center is still fluid, it can flow to adjust to the outer shell's smaller size. As the center eventually cools and solidifies, it also shrinks, but now the outer shell is already solid and can't change its shape to accommodate the smaller core.

The result is a great deal of internal stress, as the center pulls the outside in from all sides. Like a tightly wound spring, the glass is set to release a lot of energy. If you break the thin glass at the tail, a chain reaction travels like a shock wave through the drop. As each section breaks, it releases enough energy to break the next section, and so on, shattering the whole drop in less than a millisecond.

Paradoxically, the same tension also makes the Prince Rupert's drop stronger. Glass breaks when tiny scratches pull apart and spread into fractures. Since the surface is compressed by internal stress, scratches can't grow, and the glass is very difficult to break. I took a hammer to the thick end of some drops, which I got from a local glassmaker, and they stayed intact. Even the tail is stronger than it looks.

Tempered glass, common in cars and glass doors, works the same way. Jets of cold air are used to rapidly (but not too rapidly) cool the surface of hot sheets of glass, creating a milder internal tension that keeps the surface compressed at all times. That's why tempered glass is extremely strong but shatters into thousands of pieces when it does finally break. This shattering actually makes it safer, because there are no large pieces to act like knives or spears. The lesson here is that stress makes you stronger but inside that tough exterior lurks a potential explosion. And stay off my tail, OK?

About Theo Gray

Theo Gray is the author of Popular Science magazine's "Gray Matter" column, the proprietor of periodictable.com, and the creator of the iconic photographic periodic-table poster seen in universities, schools, museums and TV shows from MythBusters to Hannah Montana. In his other life, he is co-founder of the major software company Wolfram Research, creators of the world's leading technical software system, Mathematica®. He lives in Champaign-Urbana, Illinois.

Theo Gray's Mad Science: Experiments You Can Do at Home - But Probably Shouldn't
Autographed copy from the official website | Amazon

Links: Official website (Graysci.com) | Gray Matter column | Theo Gray's personal website

This article excerpts Theo Gray's Mad Science book with permission. All images and text are copyright © by Theodore Gray.

Update 2/26/10 – Great comments, guys! Congratulations to eam492 who won the book!