APPLICATION OF REFRIGERATION TO HANDLING OF MILK. 
15 
salt" upward until it cuts the curve, then read opposite on the ver- 
tical line marked "Approximate temperature ° F., 11°." The curve 
in figure 3 was plotted from the figures in Table VII, which gives 
the approximate temperatures obtained with different proportions of 
salt and ice. 
Table VII. — Approximate temperatures obtained with different proportions of salt and 
ice. 
Per cent of 
Tempera- 
Per cent of 
Tempera- 
salt in 
ture of 
salt in 
ture of 
mixture. 
mixture. 
mixture. 
mixture. 
°F. 
•F. 

32 
15 
11 
5 
27 
20 
1.5 
10 
20 
25 
—10 
One pound of ice, in melting, absorbs 144 B. T. U. This is known 
as the latent heat of fusion of ice. Salt in dissolving also absorbs 
heat, called the latent heat of solution, which varies in amount, 
depending on the density and temperature of the resulting brine. 
The heat of solution of salt in water at 32° F. varies from 58 to 
16 B. T. U., depending on the final strength of the brine obtained. 
Table VIII gives the heat of solution of 1 pound of salt dissolved in 
water at 32° F. up to the concentration given by the numbers of 
pounds of salt dissolved in 100 pounds of water. 
Table VIII. — Refrigeration available with different proportions of ice and salt. 
Salt per 
100 pounds 
water. 
Heat of 
solution. 
Total heat 
of resulting 
solution. 
Heat re- 
quired per 
pound of 
mixture. 
Salt per 
100 pounds 
water. 
Heat of 
solution. 
Total heat 
of resulting 
solution. 
Heat re- 
quired per 
pound of 
mixture. 
Pounds. 
1 
5 
10 
15 
B. T. U. 
58.0 
49.7 
40.5 
33.0 
B. T. U. 
14, 458 
14, 668 
14, 806 
14, 895 
B. T. U. 
143.0 
139.5 
134.5 
129.5 
Pounds. 
20 
25 
30 
35 
B. T. U. 
27.0 
22.5 
19.1 
16.4 
B. T. U. 
14, 940 
14, 962 
14, 973 
14, 974 
B. T. TJ. 
124.5 
119.5 
115.0 
111.0 
The curve in figure 4, based on the percentage of salt, shows the 
amount of refrigeration available per pounds of ice and salt mixture. 
This curve was plotted from the figures given in Table VIII corrected 
to a percentage basis, which were calculated from the melting of ice 
at 32° F. into a liquid at the same temperature. If, however, the 
salt is added to the ice at a temperature varying from 32° F. or, if the 
resulting brine is allowed to escape at a temperature other than 32° F., 
the amount of available refrigeration must be corrected accordingly. 
These corrections are determined by multiplying weights, in pounds 
of salt and brine, by their respective specific heats and by their dif- 
ference in temperature from 32° F. The specific heat of dry salt may 
be taken as 0.214, and as the specific heat of salt brine varies with 
its density, it may be obtained from Table IX or from curve figure 5, 
which is plotted from the figures contained in the table. 
