SOURCES OF INFECTION IN THE STABLE. 65 



disadvantage of being difficult to keep clean. The milk 

 is cooled in tank A by means of crushed ice placed in the 

 outside tank B. As shown in the figure the milk is run 

 through pipes and between cooled tin surfaces, and runs 

 into the transportation-can at the other end. Other 

 coolers will be mentioned later on under "Pasteurization 

 of Milk." 



It must be emphasized that the cooling in no way may 

 take place in the stable, although it is stated in some text, 

 books on dairying that this may very well be done. 



We must not forget, however, that the bacteria are not 



FIG. 21. PFEIFF'S COOLER. 



killed by a simple cooling of the milk. When they again 

 come under favorable conditions they at once begin their 

 activities. This fact every dairy and creamery man must 

 always keep in mind during the continued treatment of 

 the milk. If the milk is subjected to a process of manu- 

 facture it must of course have the temperature most 

 suited for the different manipulations, but when left to 

 itself the milk should always be kept as cool as the condi- 

 tions will permit. 



