220 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



Fig. 28. It was made by dividing a receiving tank of 

 100 gallons capacity into four compartments of 25 gal- 

 lons capacity each and providing an outlet valve and a 

 cover for each compartment. Fig. 29 shows a retarder 

 of the tank type. The milk from the pasteurizer enters 

 at A and is carried by the pipe to the bottom of the 

 first compartment. When this is filled, it overflows into 

 the trough C, whence the milk flows through a 

 pipe leading to the bottom of the second compartment. 

 The other compartments are filled successively in the 



TO COOLER 



Fio. 28. A simple holding" tank (B. A. I. Circ. 184). 



same manner. When the last compartment overflows 

 the milk enters the funnel B and passes to the cooler. 

 After all the milk has come over from the pasteurizer, 

 the tank is emptied by removing the funnel B and then 

 taking out the plugs from each compartment succes- 

 sively. 



A combined pasteurizer and holder, which may also 

 be used to cool the milk, is shown in outline in Fig. 30. 

 After the milk has been heated to the temperature de- 

 sired and held for the required time, it can be cooled 

 by replacing the hot water with cold water and then 

 with ice water or brine. 



