APPLICATION OF REFRIGERATION TO HANDLING OF MILK. 19 



air in the ducts and that in the bunker. With properly insulated 

 bunkers and liberal-sized ducts the circulation should be sufficiently 

 rapid to carry any air saturated with moisture to the ice bunker 

 before its moisture can be precipitated by coming in contact with 

 the cold walls of the storage room. With properly proportioned 

 ducts and insulated walls the excess moisture will be precipitated 

 in the ice bunkers and run off with the melted ice. If the air ducts 

 and bunker walls and floor are not sufficiently insulated the excess 

 of moisture will be condensed on them and will drip down on the 

 goods in storage. 



Provision should be made for thorough drainage and the drain- 

 pipe should be effectively trapped or sealed to prevent the outside 

 air from entering the cold-storage room. An efficient water seal 

 may be had by allowing the outer end of the drainpipe to extend 

 below the surface of the water in a cooling tank outside the room, and 

 as the water from the melted ice is approximately 32° F. it may be 

 utilized for further refrigerating purposes. 



As the melting point of ice is 32° F., it is obvious that, in a room 

 cooled by ice, the temperature must necessarily be somewhat higher. 

 In practice the temperatures obtained are rarely below 40° to 45° F. 

 during warm weather. In addition to the disadvantage of the com- 

 paratively high temperatures obtained by using ice as the cooling 

 medium in cold storage, the excessive moisture present in the air, 

 together with the slop incident to its use, makes it undesirable. The 

 nearer the temperature of the air in a room cooled by ice approaches 

 that of the melting ice the more sluggish becomes the circulation 

 and the higher the percentage of moisture contained in the air. Mois- 

 ture in a cold-storage room favors the growth of molds and bacteria, 

 which rot the floors and walls of the room, as well as the goods stored; 

 consequently sensitive goods like dairy products are liable to be 

 damaged by such conditions, especially if kept in storage for a con- 

 siderable length of time. However, in small plants or on the farm, 

 where goods are stored for a short period only and where ice may be 

 had at a nominal cost, either natural or artificial, this method of 

 cooling is employed to advantage. 



Great care should be exercised to prevent any cross currents of air 

 in the cooling room, for when such currents are present there is 

 danger of the cold air and warm air coming in contact with each 

 other, in which case condensation will be sure to take place on the 

 cool surfaces of the walls and ducts, thereby preventing the displace- 

 ment of the impure gases to be condensed on the surface of the ice in 

 the bunker and removed with the drip. 



It is very important that a positively guided circulation of air be 

 maintained. In order for the cold air to be most effective it should 



