MECHANIVAL REFRIGERATION 145 



scale and other foreign matter which, if permitted to enter 

 the compressor cyHnder, would tend to destroy it in a 

 very short time. 



"The oil, which always gets into the system sooner or 

 later and in greater or less quantity, depending upon the 

 care exercised to avoid it, acts as an insulator and pre- 

 vents the rapid transfer of heat from the ammonia to the 

 pipe that ought to obtain, and also occupies considerable 

 space that is required for the ammonia where the best re- 

 sults are to be obtained." 



10 



