- Cover the center of one cup with water (approximately 1 mL). Add about 0.7 g (1 teaspoon) of sodium polyacrylate powder. Some polyacrylate will stick to the bottom of the cup with the water. Pour off excess polyacrylate powder.
- Place cups stacked upside down on the center of the bench with the cup containing the polyacrylate on the bottom.
Caution: Eye protection should always be worn when handling chemicals. Adult supervision is required.
- Present the cups one at a time showing the audience that they are empty. (The polyacrylate should not be apparent at casual inspection of the cup.) Set the cups right side up in a row across the front of the table, but placed such that the audience can not see down to the bottom of any cup. The cup containing polyacrylate will be on your right.
- Pour about 100 -125 mL of water from the pitcher into the leftmost cup (i.e. fill this cup approximately 1/4 full).
- Shuffle cups ending with cup containing water on the left, cup containing polyacrylate on the right, and the empty cup in the middle.
- With some flourish, pour water from the left cup into the center cup.
- Shuffle cups ending with the cup with the water in the middle, polyacrylate cup on the right, and the empty cup on the left.
- Again with a flourish, pour the water from the middle cup into the cup on the left.
- Shuffle cups ending with the cup containing water on the right, empty cup in the middle and the cup containing polyacrylate on the left
- Pour water from the right cup into the left cup, i.e., the cup containing the polyacrylate.
- Shuffle cups.
- Clap hands with the audience while polyacrylate absorbs the water.
- Shuffle cups again.
- Starting with the cup that contains the polyacrylate and water, lift each, turn upside down to show that no water pours out, and stack in the center of the bench. The assumption to be made by the audience is that there is no longer any water in any of the cups.
The actual order of shuffling cups is not important, as long as the water is poured from cup to cup several times before being poured into the cup with the acrylate. The effect is that the water was poured from one cup to another several times, but after the last pour, it appears to have disappeared. In fact, it has been absorbed by the polyacrylate and is a gelatinous chunk stuck to the bottom of the bottom cup.
The super absorbent material, sodium polyacrylate, can be dangerous if ingested and will irritate the nasal membranes if inhaled. Avoid eye contact; if it gets into the eyes, they will become irritated. Be sure to wash your hands after use.
Dispose of excess powder and/or gelled material in the trash, not down the drain!
-----Contributed by Jackie Stewart, Mark Twain Section