50 
THE NATIONAL NURSERYMAN 
ARTIFICIAL REFRIGERATION. 
Combination Winter and Summer Storage Building for Nursery¬ 
men Illustrated and Described bv Madison Cooper — 
Gravity Brine System — Uniform Temperatures. 
MADISON COOPER, MINNEAPOLIS. 
At a temperature of 30° F. the air contains very little mois¬ 
ture, and in fact it cannot hold much, so the possibility of 
drying out nursery stock is much less when stored in a tem¬ 
perature of 30 ° F. than at 40° F. to 50° F., which many recom¬ 
mend. The capacity of air for moisture is a direct property 
of its temperature-;—the higher the temperature, the more 
moisture air will take up and hold. At 30° F. air will hold less 
come comparatively very dry and that moisture containing 
products like trees .will dry out very quickly. This case is 
stated to show the operation of this simple natural law of con¬ 
nection with the winter storage of nursery stock. Possibly 
these exact conditions might not occur in practice but they 
would be approximated. The great importance of main¬ 
taining uniform temperature and humidity is plainly illus¬ 
trated, and the cause of the drying out of trees by fluctuating 
temperatures is readily seen. 
TO OVERCOME DIFFICULTIES. 
To overcome the difficulties of winter storing as above 
outlined it is proposed to apply artificial refrigeration when 
necessary to maintain sufficiently low temperatures. By 
the term artificial refrigeration it should not be understood 
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moisture than at any higher temperature. Air which is 
saturated with all the moisture it .will hold at 30° F. contains 
1.96 grains per cubic foot. At a temperature of 40° F.— 
2.85 grains per cubic foot. This shows the rapid increase 
in capacity for moisture as the temperature of the air is in¬ 
creased. Suppose we are holding our storage room for nur¬ 
sery stock at 30° F. and a warm spell of weather comes, one 
which obliges us to close tightly all openings leading to the 
outside air. After a few days the temperature goes up to 
40° F. What is the result? The air we will say was at the 
84% relative humidity at 30° F. When the temperature of 
the air has increased to 40°, the relative humidity would be 
56%. What does this mean? Simply that the air has be- 
that a complicated ice machine is necessary. The term is 
used to express cooling effects other than those produced by 
outside atmospheric conditions. Such a refrigerating equip¬ 
ment is embodied in the Gravity Brine System illustrated 
herewith. The apparatus is simple and easily handled. It 
consists of a series of iron pipe coils connected by pipe mains. 
Primary or tank coils are placed in a suitable tank and second¬ 
ary or cooling coils are connected by the mains so that they 
form a continuous circuit for circulating chloride of calcium 
solution or brine. The tank containing primary coils is 
filled with crushed ice and salt, completely surrounding the 
coils. The chloride of calcium brine in these coils becomes 
heavier because of its lower temperature and flows down into 
