LXVI. DISCUSSION. 
the gases to leave the compressor in a super-saturated or super- 
heated condition. In these tests the conditions were identical. 
The two curves on diagram “B” shew that the temperature of 
the pressure pipe of the ammonia machine may be varied through 
a range of about 100° F. without causing a very great falling off 
in efficiency, whereas the temperature of the pressure pipe in the 
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Pressure Pipe Temperatures. 
carbonic acid machine can only be varied through a range of abou 
50° F. for the same falling off. The maximum efficiency Wa 
obtained when the pressure pipe temperature was about 122° F. 
If the temperature were raised to 176° F. the efficiency of the 
machine at once fell off. The vapours aspirated by a Linde com- 
pressor contain sufficient liquid ammonia (very finely divided) to 
absorb by its evaporation the heat produced during compressions 
the vapours leaving the compressor in a saturated condition. 
-The author has stated what in his opinion should constitute an 
ideal machine. With regard to No. 1, diagram “C” was taken 
from a twelve ton Linde compressor, it will be seen that on the 
suction stroke the pressure very nearly corresponds to -~ 
pressure shown on-the refrigerator gauge, (see line marked 
‘gauge.’) and on the compression stroke with the pressure show? 
on the condenser gauge, both the suction and delivery valves _ 
