Hand boiler

A hand boiler functions similar to the "drinking bird" toy:[1] The upper and lower bulbs of the device are at different temperatures, and therefore the vapor pressure in the two bulbs is different.

= the acceleration of gravity at the Earth's surface Sometimes a hand boiler is used to show properties of distillation.

Since the liquid both evaporates and condenses at relatively cool temperatures while in an enclosed system, the boiler can be turned upside down, and the top end can be placed in ice water.

In popular culture, hand boilers used to be sometimes known as "love meters" because the tube that separates the upper and lower bulbs is twisted into a heart shape and the volatile liquid is colored red.

Hand boilers date back at least as early as 1767, when the American polymath Benjamin Franklin encountered them in Germany.

He developed an improved version in 1768,[3] after which they were called Franklin's pulse glass or palm glass or pulse hammer (German: Pulshammer) or water hammer (German: Wasserhammer).

Hand boiler toy, built into a ballpoint pen. The warmth from the fingertips increases air pressure inside the tube, causing the liquid to rise and bubble up into the top chamber as if the liquid was boiling.