Homemade invisible ink using lemon juice

 What we need

1.  Cotton bud

2.  Lamp

3.  Plain white paper

4.  Bowl having lemon juice 

Experiment 

1.  Take the bowl having lemon juice. 

2.  Dip the cotton bud in the mixture and use it to write something on the white paper.

3. Allow the paper to dry.

4.  Now no one can read what we have written on the paper  !!!!

What happened 

1.  Secret message can be revealed when we hold the paper, close to light bulb.

2. Lemon juice contains carbon compounds which are colourless at room temperature.

3.  The heat from the light bulb breaks down these compounds and releases the carbon.

4.  Carbon oxidises when it comes into contact with the air and turns brown. 

5.  Thus our invisible message becomes visible to every one  !!!!!