13: Fire Writing

What you do

1. 
   Pour 10cm³ of water into a beaker and add the solid sodium nitrate gradually with stirring until no more will dissolve. This is a saturated solution.
2. Using a small paintbrush write a message on the filter paper. Use joined up writing but don’t complete the loops.
3. Mark the start of the message with a pencil mark and leave the filter paper to dry in air or use a hairdryer to speed up the process.
4. 
   Light the taper then blow it out so its end is just glowing. Touch the glowing end to the start of the message until the treated paper starts to glow and char.
5. Remove the taper and watch as the glow and charring works its way along the message, leaving the untreated paper untouched.