Cryophorus

Cryophorus (Gk. kruos, cold; pherein, to carry), in practical physics, is a glass tube with a bulb blown at each end, containing a small amount of water, the rest of the space being occupied by water vapour alone. If the water be confined to one bulb and the other be placed in a freezing mixture, the water vapour is condensed ; evaporation takes place at the surface of the liquid; heat is by this process abstracted from the liquid, which may thus be made to freeze without actual contact with the freezing machine.