Gray Matter: Atoms and eves

Before lava lamps and laser light, all you needed for romance was some radioactivity.
A spinthariscope.
Just look at that glow.

In 1903 there was nothing to watch on TV because there was no TV, and meeting girls was no easier than it is today. But one device solved both problems… sort of.

  • Project: watch radiation up close
  • Cost: $30
  • Time: 10 minutes
  • Difficulty: safe | | | | | crazy (Editor’s note: 2/5)

The Crookes spinthariscope, invented that year, is a small tube with a lens at one end and a zinc sulfide screen at the other. Just above the screen is a tiny speck of radium mounted on a needle. If you look into one, you’ll witness a seething, swirling light show of individual atoms going out in a blaze of glory (more entertaining than most things on TV today, I’d say). Each decaying radium atom sends out a high-energy alpha particle, which slams into zinc sulfide crystals. This triggers a process that eventually releases photons, creating visible flashes.

Achtung! Theodore Gray is a scientist trained in lab safety procedures. Do not attempt this experiment at home. For more information on Gray’s scientific pursuits, visit his website.

These atoms are so small, it would take the energy from 4 trillion of them to raise the temperature of a teaspoon of water by one degree. The fact that you can see the flash from a single atom decaying is nothing short of amazing. Your eyes must be totally dark-adapted, which means sitting in a pitch-black room for at least 10 minutes. If you were a dashing young man of science in 1903 and you brought one of these scopes to a dinner party, you would have been rude not to invite the ladies to sit next to you in a dark room. This might account for some of the early popularity of the device.

In 1947 you could get a Lone Ranger Atomic Bomb spinthariscope ring for 15 cents and a Kix cereal box top; the same toy recently cost me $200 on eBay. But modern spinthariscopes (made with safe radioactive ores) are available, and they really do work-provided, of course, that you sit in a dark room for 10 minutes first. Do with that opportunity what you will.


You can pick up a spinthariscope for $30 from Or make your own with a zinc sulfide screen ($10 on eBay) and commonly available radioactive items.

  • Hold an antistatic brush behind the screen. It sends out alpha radiation strong enough to produce a visible glow.
  • Look at vintage orange Fiestaware plates in a totally dark room with a magnifying glass to see flashes one at a time.

This story has been updated. It was originally featured in the June 2007 issue of Popular Science magazine.