Grandpa's coin purse -includes purse, coins and routine new

Explain to audience that Grandpa left you a magic coin purse.

 Two Chinese coins are shown in the palm of your left hand: One Black  and one Red. You place the Black coin  in the purse, yet, when you open your hands, both coins will be in your palm again. Then you place the Red coin in the purse and again the coin returns to your hand. Again you place the Red coin in the purse and again the coin returns to your hand. Finally you place the Black coin in the purse, open your hand and there is no coin. The last coin has disappeared!