104 MODERN FRUIT MARKETING 
idly is the heat taken up, and a lower temperature can 
be maintained in the storage room. 
The cost of maintaining a low temperature for the 
storage of fruit is difficult to estimate, owing to the vary- 
ing local conditions, but for properly constructed and 
insulated storage houses using the ice-brine system, the 
cost should not exceed $10 per 1,000 cubic feet per 
month. A thousand cubic feet will accommodate one 
earload of produce. 
Cooling Solutions Used.—It is obvious that in such 
a system some liquid would have to be used which would 
not freeze at the ordinary temperature. For this pur- 
pose two different substances have been used. One is 
the common solution of salt brine; the other is a solu- 
tion of calcium chloride in water. Salt solution was 
the one most used in the earlier development of this 
system, but it is now largely superseded by the calcium 
chloride. A saturated solution of salt and water will 
freeze at a temperature of about —7 degrees F.,=below 
zero, while a similar solution of calcium chloride will 
not crystallize under —50 degrees F.; hence the latter is 
better adapted for maintaining a lower temperature. In 
addition to this, the salt very quickly corrodes the pipes 
which need to be replaced every four or five years, while 
with the calcium chloride solution replacing once in ten 
years is sufficient. For determining the proper density of 
the solution a common hydrometer similar to the one used 
in testing lime sulphur solution could be used. For a 
salt brine solution a 25-degree reading on the hydro- 
meter would be about right, while for the calcium chlo- 
ride 20 degrees or a little less could be used. 
