AMMONIUM, CHLORIDE OF 



153 



The Evaporation of the crude Saline Solution is generally performed in square or 

 rectangular cast-iron vats, capable of holding from 800 to 1,500 gallons. They are 



encased in brickwork, the heat being applied by a firo, the flno of which takes a 

 sinuous course beneath the lining of brickwork on which the pan rests, as shown in 

 Jiff. 48. 



When the liquor is evaporated to a specific gravity of 1-25, it is transferred to the 

 crystallising pans ; but during the process of concentration a considerable quantity of 



48 



.t*r separates on the surface, which must be removed, from time to time, by skimming, 

 since it seriously impedes evaporation. 



The crystallisation, which takes place on cooling, is performed in circular tuba, 

 from 7 to 8 feet wide, and 2 to 3 deep, which are generally embedded entirely or 

 partially in the ground. To prevent the formation of large crystals, which would be 



