See how the hand boiler works

The hand boiler is designed for demonstrating that vapor pressure increases when the temperature increases. The apparatus consists of two glass bulbs that are connected with a glass tube and contain a colored, volatile liquid. Holding one of the bulbs in your hand causes the evaporation of a portion of the liquid, which forces the liquid into the other bulb. Grip one of the bulbs with your hand and watch as they “boil.”

Pulse Glass Hand Boiler