Hand boiler
A hand boiler or (less commonly) love meter is a glass sculpture used as an experimental tool to demonstrate vapour-liquid equilibrium, or as a collector's item to whimsically "measure love." It consists of a lower bulb containing a volatile liquid and a mixture of gases that is connected usually by a twisting glass tube that connects to an upper or "receiving" glass bulb. == Mechanics == A hand boiler functions similar to the "drinking bird" toy: The upper and lower bulbs of the device are at different temperatures, and therefore the vapor pressure in the two bulbs is different.