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How to Creat a Light Bulb
Creat Your Own Light Bulb
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.
How To Turn a Jar Into a Lightbulb
| WHAT YOU NEED | ||
 Tank of pure helium or argon | Tungsten welding rod or thick tungsten wire | Transparent bucket or large-mouth jar |
| Stick welder | Tinfoil or plastic wrap | Safety glasses |
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Clamp a 1/16-inch diameter tungsten welding electrode (available at any welding supply store or well-stocked hardware store) between the two electrode clamps of a stick welder that have been secured in an upright position.
Invert a glass bowl or pitcher over the setup, but keep the glass well away from the electrode and clamps.
Seal the bottom loosely with tinfoil (don't let it short out the electrodes).
Run a tube from a helium tank through the tinfoil. Use pure helium, not balloon helium, which sometimes has oxygen mixed in to prevent asphyxiation. 
Turn on the helium and keep a steady stream flowing into the bowl. It will rise to the top and eventually fill the container.
Turn on the welder and stand by to switch it off in a hurry if things get out of hand. Potential problems include the glass breaking from the heat, or the electrode burning through the glass. If the electrode smokes, it means there's not enough helium in the container, or your helium is not pure.
Alternately, use a tank of argon, in which case the bowl should be right side up with the electrodes coming down from the top (because argon is heavier than air).How To Create a Melting Spoon
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
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.
How To Create a Melting Spoon
| WHAT YOU NEED | ||
| Bismuth, indium and tin | Stainless-steel pan | Rubber or plastic spoon mold |
1
Make a mold by casting or forming jewelers' rubber around the object you want to duplicate.
2
Weigh out the metals in the correct ratio: 51 percent indium, 32.5 percent bismuth and 16.5 percent tin. If you're within a gram, it'll still work.
3
Combine the ingredients in a stainless-steel measuring cup and heat directly on a stove over low heat. You'll need to go well beyond the melting point of the final alloy in order to get the tin and bismuth to combine with the indium. Stir continuously.
4
Let the alloy cool, then reheat it over nearly boiling water. A double-boiler works, or you can just hold the measuring cup in the hot water for a minute or two.
5
Pour the molten metal into the mold. While it may be tempting to hold the mold in your hand, the metal is hot enough that it will burn if you spill too much on yourself. It is no more, but also not any less, dangerous than boiling water.
6
Wait until you are sure the metal has solidified in the mold. This may take longer than you think since the melting point is so low.
7
Carefully extract the spoon from the mold.
8
Enjoy! Stirred in nearly boiling water, a typical spoon will melt in seconds.
Source Official webpage: Gag with a Spoon
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