CARE OF MILK ON THE FARM 



319 



the surface of the cooler. When the milk reaches the bot- 

 tom, it is caught in a trough from which it drains into the 

 milk can. 



The type of cooler shown in figure 1G9 requires running water 

 under pressure, as the water must pass upward through the 

 cooler and out 

 through a drain at 

 the top. The warm 

 milk flows down- 

 ward from the sup- 

 ply tank over both 

 sides of the cooler 

 and drains off at 

 the bottom. The 

 coldest part of this 

 cooler is at the bot- 

 tom, so that the 

 w a r m milk first 

 comes in contact 

 with the warmer 

 portion at the top 

 and comes in con- 

 t a c t with colder 

 portions as it 

 passes to the bot- 

 tom. 



Coolers, like oth- 

 er milk utensils, 

 require sterilizing 

 after each using. 



Cooling tanks. — 

 While surface cool- 

 ers are a great aid 

 in cooling milk and cream, they do not complete the cooling pro- 

 cess. A cooling tank is, therefore, necessary to cool the milk 

 to a low temperature and hold it there. 



Cooling tanks are generally constructed of concrete or of wood 

 lined with a nonrusting metal. Such tanks must be watertight 

 and should be provided with an outlet at the bottom to drain 

 off the water when cleaning them. The walls should be suffi- 

 ciently high to allow the upper level of the water to reach the 

 necks of the milk cans, and the drain pipes should be arranged 

 to hold it at this level. Narrow strips should be placed in the 



Fig. 169. — Insulated concrete cooling tank partially sunk 

 in the cement floor; also a surface cooler in opera- 

 tion. 



