Scenting coins

Three different coins lie in a plastic dish. You close your eyes while another person takes out one coin, holds it for several seconds in his closed hand, and puts it back. Now hold the coins one after the other briefly to your upper lip and find out immediately, to everyone’s astonishment, which coin was taken from the dish. Since metals are very good conductors of heat, the coin warms up immediately
in the hand. But plastic is a poor conductor, so hardly any heat is lost to the dish when the coin is put back. The upper lip is particularly sensitive and reveals the smallest temperature difference in the coins, so that you can detect the right one immediately. Before the trick is repeated it is a good idea to lay the coins on a cold stone floor to conduct away the heat.