it's a mystery

If you have secrets (top secret secrets) but want to share them with a select few, you might want to purchase this invisible ink ($16 from the Library Shop). Just be sure to instruct the receiver to expose the paper to some heat (don't torch it, try a light bulb)--the invisible ink will turn blue and then disappear again when the ink cools off. Beats swallowing the paper or implementing some sort of self-destructive device a la Mission Impossible. But hey, if you don't have $16 but still want to share your secrets, check out these instructions from Wiki How on how to make a secret note. [Invisible ink found via Cool Hunting]