64 BULLETIN 98, U. S. DEPARTMENT OF AGRICULTURE. 
ery and properly arranged and proportioned accessories the cost of 
repairs and operation is reduced to a minimum. 
In the summer months the refrigerating plant is often required to 
operate continuously in order to handle the increased amount of 
milk during the flush season, and, furthermore, there is a greater 
amount of refrigeration required on account of the higher summer 
temperature. A breakdown at this time would result in the prob- 
able loss of the stored products; besides, the daily supply of milk 
and cream which arrives in the plant at a temperature that will 
cause the rapid development of bacteria if held even for a short 
period. During the summer months the temperature of the con- 
densing water will be higher, and consequently a greater quantity 
will be required for satisfactory operation. 
With properly proportioned pipe coils, brine tanks or congealing 
tanks, and good air circulation within the cold-storage room, cool and 
dry air will be obtained and a lower temperature and purer atmos- 
phere than is possible with ice. The temperature obtained in the 
average refrigerator cooled with ice is seldom below 45° or 40° F., 
and the air always contains more moisture than it should for the best 
results. 
When employing a properly designed mechanical refrigerating 
plant the temperatures are under perfect control of the operator, 
regardless of weather conditions; consequently the result is a higher 
grade and more uniform product. It is absolutely necessary in 
manufacturing the highest grade dairy products to be able to control 
the temperatures at will. 
As the refrigerating plant is generally operated by persons unskilled 
in the management of machinery of this type, it should be as simple 
as possible in its construction and operation, especially in the smaller 
plants. In the larger plants, however, where an experienced attend- 
ant is employed, the equipment may be more elaborate. The appa- 
ratus should be designed to occupy as small a space as possible con- 
sistent with strength and efficiency, and as it is to be operated by 
unskilled persons, nothing but the very best material and workman- 
ship should be used in its construction. 
In order to keep the size of the refrigerating plant as small as pos- 
sible, it is advisable to provide storage tanks of ample capacity. 
The brine should be cooled and a large quantity held for quick action 
when needed, as when a supply of warm milk is received into the 
plant and it is necessary that it should be cooled in the shortest 
possible time. And, further, the cold brine in the storage room can 
be depended upon to hold the temperatures in case of a temporary 
shutdown of the refrigerating machine. 
In view of the fact that the quantity of milk or cream is liable to 
vary greatly from day to day, depending upon the supply from the 
