The apparatus consists of two small glass balloons (diameter 4.2 cm) containing alcohol. They are connected by a capillary tube (length 19.5 cm). The boiler is made to work by filling both balloons a quarter full with a liquid having low vapour pressure, such as alcohol. After boiling the liquid long enough for the vapours produced by ebullition to force out all the air, the apparatus is flame closed in the middle of the capillary tube. In this way, inside the balloons only the vapour pressure of the liquid acts. Holding the apparatus with the two balloons pointing upwards the liquid in them reaches the same level; but, if we hold one of them in the palm of a hand, the heat supplied by this generates a vapour pressure that forces all the liquid into the other balloon, thus causing violent ebullition.


Bibliografia:
Ganot (1864), p. 254


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