Materials:
1. Lemon
2. Cotton swab or cocktail stick
3. Light bulb
4. A sheet of paper.
Instruction:
1. Squeeze the juice out from a lemon on a small bowl.
2. Dip a painting brush or cocktail stick into the lemon juice then write a message or draw a picture on a piece of paper.
3. Leave the paper to dry. Once dry the message or picture will be hard to see.
4. To read the message, carefully hold the paper up to a heat source, such as light bulb. (Be careful, too much heat will cause the paper to ignite)
Explanation:
Lemon juice is acidic and weakens paper. When paper is heated, the remaining acid turns the writing brown before discoloring the paper.
