PIRA Classification: 4A30.20
Description: A brass sphere is slightly too large to fit through a brass ring. If the ring is heated with a burner, it will expand just enough to let the ball through. Also, the ball can be cooled with liquid nitrogen, allowing it to pass through the (room temperature) ring.
Special Instructions: Don't leave the heated ring around a ball.
Condition: Ok
Setup time: 2 minutes
Safety Issues: Don't burn yourself.