103 MODERN FRUIT MARKETING 
salinometer,” and which will not freeze at zero. If a 
temperature below zero is required, chloride of calcium 
brine is used, a mixture of three pounds per gallon 
will not freeze at 8 degrees below zero. 
‘In the brine system the large body of chilled brine 
contained in the brine tank and pipe coils is a storage 
for cold, and is a reserve that can be used to maintain 
the temperature desired in the rooms for a considerable 
length of time, by merely operating the brine circulat- 
ing pump. It frequently being only necessary to oper- 
ate the compressor during the day to maintain the tem- 
perature during the entire 24 hours. The ease with 
which the temperature is controlled, and the absence of 
any danger from escaping ammonia in the rooms are the 
principal features that commend this system. 
Direct Expansion System.—‘‘In the direct expansion 
system the ammonia expansion coils are placed directly 
in the rooms to be cooled, the heat being absorbed by 
the evaporation of the ammonia in its passage through 
the pipe coils to the compressor, only one system of 
pipes being required. The expense of the outfit being 
very materially reduced, as compared with the brine 
system, the brine tank, the brine pump and the secondary 
system of pipes for brine circulation being dispensed 
with and a somewhat greater efficiency is obtained. 
“‘The arrangement of the pipe coils in the cold stor- 
age rooms is the same for direct expansion as for brine 
circulation, but the valves and fittings must all be of 
special construction, and the pipes are put up with the 
greatest care so as to be absolutely tight to avoid the 
2A salinometer is a hydrometer graduated to show the percentage of 
salt in a solution, : 
