COOLING AND AERATION 207 



bonic acid gas. These gases should be removed as quickly 

 as possible after milking by exposing the milk in thin 

 sheets to the atmosphere. Fortunately the construction 

 of modern coolers is such as to make it possible to do 

 the cooling and aerating in one operation. 



Formerly it was customary for dairymen to aerate 

 their milk before cooling. Such practice is known to give 

 somewhat better aeration than is possible where the cool- 

 ing and aerating are performed in the same operation; 

 yet the difference is so slight that consumers cannot detect 

 it. The practice of aerating first and cooling afterward 

 is therefore being abandoned. 



Coolers. All modern coolers permit cooling with ice 

 water. Without this a sufficiently low temperature can- 

 not be obtained to stop practically all bacterial growth. 

 To meet the requirements of dairies of different sizes, sev- 

 eral styles of coolers are herewith described and illus- 

 trated. 



Corrugated Cooler. This style of cooler is shown in 

 Fig. 58, which also shows a desirable method of fastening 

 it. It is especially adapted to dairies having from fifteen 

 to thirty cows. The cooler consists of two parts : An 

 upper section which is used to cool milk and cream with 

 uniced water, and a lower section through which ice water 

 is circulated. 



A storage tank for well water may be placed above 

 the ceiling. From this the water is admitted to the upper 

 section through the valve which is used to regulate 

 the flow. As shown by the arrows the water enters the 

 section at the bottom and discharges at the top. The 

 waste water may be conducted to the feed water tank of 

 the boiler, to a watering trough, or other places where 

 it may be useful. 



