STEAM 85 



the turning of water into steam does. In the ammonia ice 

 apparatus the heat comes from the water to be frozen. 



The apparatus is shown in Fig. 71. In this apparatus the water 

 is not frozen directly by the evaporation of the liquid ammonia; but a 

 brine is cooled to 15 C. or 20 C., and this cold liquid is used to 

 freeze the water. The brine is a water solution of salt or of calcium 

 chloride, and freezes far below the freezing temperature of water. 

 The cold brine is also used in cold-storage warehouses, and in refriger- 

 ator cars, to produce a low temperature. In this way butter, eggs, 

 meat, fruit, etc., are kept cold, and prevented from spoiling (Fig. 72). 



FIG. 72. t 



Rooms for storage of meat are cooled by means of a cold brine 

 distributed through pipes. 



"Iceless" refrigerators are now being made. They are really refriger- 

 ating machines, and are kept cold by the rapid evaporation of 

 liquid ammonia. 



89. Steam. Steam is water in the vapor form. When 

 steam issues briskly from a vessel of boiling water, as 



