Cloud chamber from the A. C. Gilbert U-238 Atomic Energy Lab, ca. 1950.

Cloud chamber from the A. C. Gilbert U-238 Atomic Energy Lab, ca. 1950.

Science History Institute/Gregory Tobias

Hazardous Fun

Was this really the world’s most dangerous toy?

In 1950 the A. C. Gilbert Company released a toy that promised to unlock the secrets of atomic power. The U-238 Atomic Energy Lab included a small amount of radioactive matter and the cloud chamber shown here, a device that allowed the viewer to watch alpha particles travel at roughly 10,000 miles per second, giving off a characteristic glow. Gilbert’s toy catalog promised the cloud chamber would create “awe-inspiring sights! . . . Electrons racing at fantastic velocities produce delicate, intricate paths of electrical condensation.”

Of course, the wonder of atomic engineering was what earned this Gilbert cloud chamber a reputation as “the world’s most dangerous toy.” It was quickly pulled from the market, but the manufacturer continued to assure parents that the tiny bit of radioactive material included with each set was essentially harmless (probably about as harmful as exposure to ultraviolet rays from the sun).