What's your secret message?: With just a few household items--
and a little bit of science--you can make an invisible ink
message that will reveal itself under just the right conditions.
Image: iStockphoto/JoKMedia Have you ever wondered how spies and
secret agents could leave secret messages? Invisible ink might
sound high tech, but you can create—and read!—a top secret
message with one simple kitchen ingredient: lemons. George
Washington's army used this same concept to send secret messages
during the American Revolutionary War. What message will you
write? Lemon juice—and the juice of most fruits, for that
matter—contains carbon compounds. These compounds are pretty
much colorless at room temperature. But heat can break down
these compounds, releasing the carbon. If the carbon comes in
contact with the air, a process called oxidation occurs, and the
substance turns light or dark brown. • One half of a lemon (use
caution when cutting) • One half teaspoon of water • Small bowl
• White paper • A lamp with a li