Some people believed the world would end on May 19, 1910. The most famous comet, Halley's Comet, had returned to the night sky and would pass so close to the Earth that we would pass through its tail on May 19^th. What would the comet leave in our atmosphere? Astronomers hoped to answer that question with the relatively new technique of spectroscopy. Among the many chemicals found in the spectra, they found evidence associated with the poisonous gas, cyanogen.

Most scientists figured that the tails of comets were basically dust clouds and any particles of cyanogen would be few and far between so we wouldn't even notice. Others latched on to that 'what if?' and foretold the end of every living thing. As the day got closer, more people worried about 'what if?' and sales of "Comet Pills" to counteract cyanogen poisoning skyrocketed.

On the morning of May 20^th, no one had died from cyanogen poisoning, even the ones that did not take any Comet Pills.

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It's very easy to make a glow in the dark crystal geode. The 'rock' is a natural mineral (eggshell). You can use one of several common household chemicals to grow the crystals. The glow comes from paint, which you can get from a craft store.

Glow in the Dark Geode Materials

• eggs
• glow in the dark paint (I used GlowAway™ washable glowing paint)
• very hot water (I used my coffee maker)
• borax, alum, epsom salts, sugar, salt, or use another crystal recipe
• food coloring (optional -- I used neon green coloring)

Prepare the Glowing 'Geode'

1. There are two ways to crack your eggs. You can carefully crack the top of the egg by tapping it on a countertop. This will give you a deep geode with a smaller opening. Alternatively, you can crack the equator of the egg or carefully cut it with a knife. This will give you a geode you can open and put back together.
2. Dump the egg or make scrambled eggs or whatever.
3. Rinse out the inside of the eggshell with water. Peel away the interior membrane so you are left with only the shell.
4. Allow the egg to air dry or carefully blot it dry with a paper towel or napkin.
5. Use a paintbrush, swab, or your fingers to coat the inside of the eggshell with glowing paint.
6. Set the painted egg aside while you mix the crystal-growing solution.

Make the Crystal Solution

1. Pour hot water into a cup.
2. Stir borax or other crystal salt into the water until it stops dissolving and you see some solid at the bottom of the cup.
3. Add food coloring, if desired. Food coloring does not get incorporated into all crystals (e.g., borax crystals will be clear), but it will stain the egg shell behind the crystals, giving the geode some color.

Grow the Crystals

1. Support the shell so that it won't tip over. I made a little nest for mine in a crumpled napkin that I set inside a cereal bowl.
2. Pour the crystal solution into the shell so that it is as full as possible. Don't pour the undissolved solid into the eggshell, just the saturated liquid.
3. Set the shell somewhere where it won't get knocked over. Allow crystals to grow for several hours (overnight is shown) or as long as you like.
4. When you are satisfied with the crystal growth, pour out the solution and allow the geode to dry.
5. Phosphorescent paint is activated by exposing it to bright light. Black light (ultraviolet) produces a very bright glow, also. The duration of the glow depends on the paint you use. My geode glows for about a minute before it needs to be recharged. Some paints will produce geodes that glow for a few seconds. Other paints may glow for many minutes.
6. Store your geode in a dry location, protected from dust.

Glow in the Dark Crystal Snowflake | Copper Sulfate Geode

Have you noticed a significant proportion of my science magic tricks involve fire? I don't actually go around my house lighting things on fire, though I do confess to a certain fondness for those types of projects. I collected my fire magic magic tricks into their very own section, so if you are into fire demonstrations or elemental magic you can find the fire magic tricks in one place. Enjoy!

May 18^th is the birthday of the man who brought us two chemicals that had profound effects on our environment, Thomas Midgley, Jr. He was an American mechanical engineer and chemist who invented tetraethyllead and dichlorodifluoromethane, known by their trademarks Ethyl and Freon. Ethyl was a gasoline additive created to reduce engine knock. It was less expensive than rival additives like ethanol, but contained the toxic element lead. Leaded gasoline was a standard for vehicles from the 1920s to the 1980s dumping lead into the environment the entire time.

The other chemical he discovered was Freon. Freon is actually a collection of chlorofluorocarbon chemicals. They were used in refrigerators, air conditioners, and fire suppression systems. It was a wildly successful replacement for old, less effective refrigerants like methane and ammonia. The problem came when Freon was released into the atmosphere. It would rise into the upper atmosphere and react with the ozone layer where it would break the oxygen bonds and deplete the amount of ozone. The effects were well documented by the 1990s when entire regions of the atmosphere near the poles were missing ozone.

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