This week's experiment seems to be a magic trick, but the basic idea is very useful. It is the idea behind the self sealing tires that seal themselves after you run over a nail. To try this, you will need:

- a sheet of newspaper
- rubber cement. Other kinds of glue will not work.
- talcum powder or flour
- sharp scissors

Cut a strip of newspaper about an inch wide. Paint one side of the paper with rubber cement. Be sure to paint the entire surface with a thin coat of the cement. Let the paper sit for about 5 minutes. The cement will still be sticky. Sprinkle a layer of talcum powder onto the rubber cement. Cover the entire surface with talcum powder. Carefully lift the strip and shake off the excess powder. Now cleanup all the powder that you spilled on the floor.

Fold the strip of paper in half, with the powdered side on the inside. Cut through the paper at the fold. Be sure to use a sharp pair of scissors, to get a good cut. Take hold of one of the bottom ends of the paper and lift it up. Even though you cut out the center of the strip, it still seems to be all in one piece. Fold it in half and cut it again. Once again, it heals itself.

The rubber cement forms a sticky layer between the paper and the talcum powder. As you cut the paper, you bring the layers of rubber cement together and they stick, causing the two strips to hold together.

Use your imagination and you may be able to come up with all sorts of ideas, based on this simple experiment. Imagine a self sealing space suit that automatically patches itself if you get a leak. Or a self sealing drink box that reseals itself when you remove the straw. Thinking about things like this can be a lot of fun. If you think about it enough, you might invent something wonderful. If you do, remember where you got the idea.