Purpose: To demonstrate the effect of atmospheric pressure.

Rectangular steel can, vacuum pump, hand-operated air pump or compressed-gas cylinder.

1. Insert the stopper into the can, connect the hose, and pump the air out. The result is usually very impressive.
2. Use the hand-operated pump to pressurize and return the can nearly to its original shape. Alternatively, pressurize by slowly and carefully injecting gas from a compressed-gas cylinder.

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