PASTEURIZATION 



135 



and the milk can pass from o to p. If the temperature falls, the 

 pressure of the horizontal rod is withdrawn from the valve, which is 

 then caused to close the opening by means of a spring, s, so that the 

 milk cannot flow to the pasteurizer; thereupon the discharge of milk 

 immediately ceases, and not until the milk has been sufficiently 

 heated will the valve open again, so that fresh milk may enter and 

 expel that already heated from the apparatus. 



FIG. 8. 



Schmidt's milk-cooler; o, entrance for cold water ; b, exit for cold water. 



From the pasteurizer, the milk must be passed over 

 or through a cooler in order to lower the temperature as 

 much as possible, for otherwise it would soon spoil. 



From the cooler, the milk should be drawn directly 

 into the container from which it is to be sold. Fig. 8 

 represents a cooler which consists of a spirally fluted 



