ARTIFICIAL REFRIGERATION AND ICE MAKING. LXV. 
before admission to the refrigerator. The two curves shew that 
at a normal temperature (60° F.) the ammonia machine is 20% 
more efficient than the carbonic acid machine, and even with 
cooling water below freezing point, 5% more efficient, (in this case 
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Temperature of refrigerant measured before the regulating valve. 
the cooling water consisted of brine. With cooling water above 
87° F. (that is above what is always considered to be the critical 
Point of carbonic acid) the ammonia machine required just half 
the power required by the carbonic acid machine for doing the 
Same amount of refrigerating work under exactly the same con- 
ditions. The above results are practically confirmed by the 
res given in the paper read by Mr. Hesketh.’ 
He, Mr. Statham, carried out several experiments to show how 
the efficiencies of the two machines compared when working with 
& low and a high temperature of pressure pipe, that is allowing 
Seite ieee ae 
1 See page xlviii, ante and Engineering November 1, 1895. 
5—July 15, 1896, 
