A cryophorus is a glass container containing

liquid water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a s ...

and

water vapor (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous pha ...

. It is used in

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

courses to demonstrate rapid

freezing Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. In accordance with the internationally established definition, freezing means the solidification phase change of a liquid o ...

evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

. A typical cryophorus has a bulb at one end connected to a tube of the same material. When the liquid water is manipulated into the bulbed end and the other end is submerged into a freezing mixture (such as

liquid nitrogen Liquid nitrogen—LN2—is nitrogen in a liquid state at low temperature. Liquid nitrogen has a boiling point of about . It is produced industrially by fractional distillation of liquid air. It is a colorless, low viscosity liquid that is wide ...

), the gas pressure drops as it is cooled. The liquid water begins to evaporate, producing more water vapor. Evaporation causes the water to cool rapidly to its

freezing point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...

and it solidifies suddenly.Wollaston's cryophorus was a repurposed "pulse glass". The "pulse glass" or "pulse hammer" (German: ''Pulshammer'') was a toy / novelty that had existed in Germany since the 1760s and perhaps earlier. In 1767

Benjamin Franklin Benjamin Franklin ( April 17, 1790) was an American polymath who was active as a writer, scientist, inventor, statesman, diplomat, printer, publisher, and political philosopher. Encyclopædia Britannica, Wood, 2021 Among the leading inte ...

visited Germany, saw a pulse hammer, and in 1768, improved it. See: *
Benjamin Franklin's letter to John Winthrop of 2 July 1768
* * Franklin's pulse glass consisted of two glass bulbs connected by a U-shaped tube; one of the bulbs was partially filled with water in equilibrium with its vapor. Holding the partially filled bulb in one's hand would cause the water to flow into the empty bulb. For videos of Franklin's pulse glass in operation, see: *
Pulse Glass
*
Franklin's pulse glass
Wollaston was familiar with the pulse glass's construction: from (Wollaston, 1813), p. 73: "The mode of effecting this .e., expelling air from the cryophorusis well known to those who are accustomed to blow glass."
In the case of Franklin's pulse glass, water in the filled bulb was caused to evaporate by heating the water in the filled bulb. In the case of Wollaston's cryophorus, water in the filled bulb was caused to evaporate by cooling and condensing the water vapor in the empty bulb.
See also: * * Wollaston's cryophorus was a precursor to the modern

heat pipe A heat pipe is a heat-transfer device that employs phase transition to transfer heat between two solid interfaces. At the hot interface of a heat pipe, a volatile liquid in contact with a thermally conductive solid surface turns into a vapor ...

History

The cryophorus was first described by

William Hyde Wollaston William Hyde Wollaston (; 6 August 1766 – 22 December 1828) was an English chemist and physicist who is famous for discovering the chemical elements palladium and rhodium. He also developed a way to process platinum ore into malleable ingo ...

in an 1813 paper titled, "On a method of freezing at a distance."

References

Notes

Laboratory glassware Phase transitions Physics education Thermodynamics {{Thermodynamics-stub