You are a detective and you have some secret information. Important to be kept secret. How do you write a secret massage that magically appears when needed?
Things Required:
Soup bowl
Tincture of Iodine
Lemon
Notebook paper
Cup
Art brush
Directions:
Pour 1/2 cup of water into a bowl. Add 10 drops of Tincture of Iodine to the water and stir. Squeeze the juice of the lemon into the cup. Cut a section from the notebook paper. The paper must fit inside the bowl. Dip the art brush into the lemon juice and write a message on the piece of paper. Allow the juice to dry on the paper. Submerse the paper in the iodine solution in the bowl.
This Is What Happens:
The paper turns a blue-purple except where the message was written. The words are outlined by the dark background.
Science Behind It:
The starch in the paper combines with the iodine forming iodine-starch molecules. These molecules are blue-purple in colour. Vitamin C combines with iodine to form a colourless molecule. The area covered with lemon juice remains unchanged because the paper is coated with vitamin C from the lemon.
