The Effect:
A coin is taken in a handkerchief. The handkerchief is placed over a glass of water and the coin is dropped in. The audience sees the coin in the glass, then upon a second look, the coin has dissolved out of the glass.
The Trick:
In order to do this effect, you need a clear glass cup, with no special bottom. Hold the glass in one hand, and put the handkerchief over your other with the coin on top of the handkerchief. Slide the coin between your index finger and thumb, and cover the water filled glass the first time. Tilt it by raising your fingers upwards. This is unknown to the audience. After that, the coin is held in the handkerchief, above the tilted outside of the glass. When it is dropped, it should strike the outside of the glass then it slides into your fingers. The noise makes the audience think the coin landed inside the glass, but you just maneuver it under the glass so that it really looks like it is in the glass. Allow the audience to look straight down at the coin when showing it to them. Then, cover the glass back up with the handkerchief, and grab the top of the glass. You put the glass down on the table with the handkerchief over it. Secretly, the coin will be in your opposite hand, which you nonchalantly slide into your pocket, drop the coin, and slide it back out while you’re removing the handkerchief from the glass.