116 DAIRY LABORATORY GUIDE 



two and one-half tons of ice or five tons of refrigerating 

 capacity. It requires from twelve to eighteen hours 

 to cool off a room containing 1000 cubic feet and to 

 make one ton of ice, depending on the perfection of 

 the insulation, on the outside temperature, and on 

 the contents of the cold storage room. 



Ice ordinarily does not reduce the temperature 

 below 40 F., but by running the engine continually 

 the temperature can be reduced as low as desired, 

 even to zero. 



A two-story plant: The brine tank can be placed 

 right above the cold-storage room, and thus keep it 

 cool after the machinery stops. A building 24 by 

 30 feet is ample for a dairy of 2500 quarts capacity. 



Direct-expansion system is much cheaper than the 

 brine system, providing ice is not manufactured for 

 sale; the brine tank, brine pump, and secondary 

 system of pipes for brine circulation being dispensed 

 with, and also a greater efficiency is obtained. Only 

 about two-thirds of the pipe surface is required to 

 produce the same effect. See illustration. 



A Non-frosting Gage Glass 



A device to prevent frost from gathering on the 

 glass gage is described by R. L. Shipman. The 

 method is simply to jacket the ordinary form of 

 gage glass with another glass of larger diameter, so 

 that there will be an annular space of an eighth of 

 an inch or so between the glasses. Then place a soft 

 rubber ring between the glasses at each end, making 

 air-tight joints. The air thus enclosed between the 



