Scyence: Chemistry, engineering, and pyrotechnics.

This is a paper towel soaked in copper nitrate solution. Copper nitrate, unlike most nitrates, makes the paper burn more slowly instead of more quickly. But the really remarkable thing about it is what is left behind after it is done burning: copper. Instead of ash, burning a paper soaked in copper nitrate causes the paper to leave a residue of copper in the shape of the paper, which, because it is so thin, quickly curls up due to the heat of the burning paper.