You will need
  • Small dishes, onion or lemon, milk or sweet (salty) water brush or a fountain pen, a candle or iron
Grate on a fine grater onion and squeeze through cheesecloth juice into a Cup. Ink ready. Instead of onions you can take fresh Apple.
In a small amount of water mix sugar or salt. It is also invisible ink.
Cut the lemon and several slices squeeze the juice into a small container. You got invisible ink.
Pour in a little Cup of milk. Can be diluted with water. In any case, you have manifested the ink.
Now test the resulting ink formulations. To do this, take a sharpened stick, a thin brush or a fountain pen and, having dipped in invisible ink, write on a piece of paper a few words. Or something draw. Allow to dry. Letters or the figure became invisible. Iron a piece of iron – the ink will appear. You can hold the letter over the fire (at a distance of 10 cm), we obtain the same result. The secret of invisible ink is simple: some of the substances contained in lemon juice, onions, milk, sweet or salt water, when exposed to heat are destroyed faster than light paper. This chemical process and allocates products of combustion.