during condensation, but that the amount of heat thus set free is
exactly equal to the amount absorbed during vaporization. (See
Laboratory Manual.)

We learn that the heat of vaporization is the same whether it is
considered as the heat absorbed by 1 gram of water in its change to
steam, or as the heat given out by 1 gram of steam during its
condensation into water.

24. Practical Application. We understand now the value of steam as a
heating agent. Water is heated in a boiler in the cellar, and the
steam passes through pipes which run to the various rooms; there the
steam condenses into water in the radiators, each gram of steam
setting free 536 calories of heat. When we consider the size of the
radiators and the large number of grams of steam which they contain,
and consider further that each gram in condensing sets free 536
calories, we understand the ease with which buildings are heated by
steam.

Most of us have at times profited by the heat of condensation. In cold
weather, when there is a roaring fire in the range, the water
frequently becomes so hot that it "steams" out of open faucets. If, at
such times, the hot water is turned on in a small cold bathroom, and
is allowed to run until the tub is well filled, vapor condenses on
windows, mirrors, and walls, and the cold room becomes perceptibly
warmer. The heat given out by the condensing steam passes into the
surrounding air and warms the room.

There is, however, another reason for the rise in temperature. If a
large pail of hot soup is placed in a larger pail of cold water, the