ARTIFICIAL ICE 99 



Ammonia gas is driven by the pump C into the coil D 

 (Fig. 56) under a pressure strong enough to liquefy it, the 

 heat generated by this compression being carried off by cold 

 water which constantly circulates through B. The liquid 

 ammonia flows through the regulating valve Finto the coil E, 

 in which the pressure is kept low by the pump C. The ac- 

 companying expansion reduces the temperature to a very low 

 degree, and the brine which circulates around the coil E ac- 

 quires a temperature below the freezing point of pure water. 

 The cold brine passes from A to a tank in which are im- 

 mersed cans filled with water, and within a short time the 

 water in the cans is frozen into solid cakes of ice. 



