BRIDGEPORT, W. Va. (WDTV) - Keeping with the Halloween spirit, this experiment is called ghost marbles.
I went out and bought these jelly marbles at your local craft store. Let them soak overnight in water to grow. I have them in a clear bowl now and drained of water. A secret message is underneath.
We can read this message by simply adding water. When you add the water to the bowl, the marbles disappear just like ghosts. Now that they disappear, you can read the message. The marbles aren't gone though. They are still there just invisible.
How do the ghost marbles disappear?
The marbles are made out of a super absorbent polymer than absorbs the water and grows in size. They are 99% water when full hydrated. You can barely see them when in the water because the light passing through the marble is refracted only a little around the edge of the marble. They become invisible because they have an identical index of refraction with the water in the bowl.