1869.] 



of Ice and Cold. 



203 



ether macliiiie. The woodcut, Fig. 2, represents this appar^itus. 

 A strong, vertical boiler, a, is charged with a concentrated solution 



Fii 



of ammonia, to which heat is applied under a pressure of eight or 

 nine atmospheres — 100 to 135 lbs. per square inch — and the 

 mixture of gaseous ammonia and steam produced, passes off through 

 an ascending coil of pipe, b, attached to the upper end of the boiler, 

 into a tubular condenser, d, surrounded by cold water, where the 

 distillate is cooled and liquefied under the pressure above stated. 

 The condensed liquid collects in a receiver, z, and thence passes by 

 the pipe eee into the refrigerator f at a rate which is regulated 

 by a special contrivance. 



The refrigerator f consists of a close vessel with tubes, /, 

 closed at the bottom and open at the top, fitting tightly into the 

 cover, so that the liquid ammonia surrounds them. Into these 

 tubes cylindrical vessels are placed, containing the water to be 

 frozen. The upper end of the refrigerator is connected by means 

 of a pipe, G, with a vessel, h, within which the gaseous ammonia 

 discharged from the refrigerator comes in contact with a continuous 

 supply of cold water and is thereby alisorbed, while the solution of 

 ammonia produced is removed from the bottom of the vessel h by 

 the pump I. In this way the gaseous ammonia is removed from 

 the refrigerator and the pressure kept so low that the liquid am- 

 monia is vaporized continuously, thereby abstracting heat from the 

 contents of the tubes /. 



The solution of ammonia produced in the absorber h is forced 

 by the pump i through the pipe h h into the outer casing of a 



