Cryophorns

Cryophorns (Gr. kryos, 'cold,' and phero, 'I carry') is an instrument consisting of a glass tube with a bulb at both ends, used for showing the diminution of temperature in water by evaporation. In constructing it the whole of the air is extracted, leaving practically a vacuum inside. A little water is present in one of the bulbs, and when the second bulb, containing only water-vapour, is placed in a freezing mixture, the vapour condenses, which causes more vapour to rise from the water in the first bulb. The result of this vaporation from the first bulb is the abstraction of much heat, and ultimately the remaining water passes into a frozen state.