4 BULLETIN 973, U. S. DEPARTMENT OF AGEIGULTUEE. 



can, because then all the milk from each producer can be mixed 

 thoroughly and a fair sample taken. A two-compartment weigh can 

 facilitates the weighing and sampling.^ 



From the time the milk is received and dumped it should be 

 handled rapidly and should be exposed to contamination as little as 

 possible. After the milk is weighed it usually passes through a 

 clarifier or a filter to remove any dirt present. While large plants 

 generally use a clarifier, very satisfactory results may be obtained 

 with the use of a filter consisting usually of layers of cheesecloth 

 and cotton, and considerable expense m equipment eliminated. 

 There are also several types of mechanical filters now on the market 



Fig. 3.— Testing milk for butterfat content. 

 PASTEURIZING AND COOLING. 



It is important that the milk be properly pasteurized, and a com- 

 petent and reliable man should be assigned to this work. 



The primary purpose of pasteurization is the destruction of all 

 pathogenic organisms in order to make the milk safe. Where milk is 

 properly pasteurized, disease-producing organisms and nearly all 

 other bacteria are destroyed, so that besides making the milk safe 

 the keeping quality is improved. 



In pasteurization two main objects are desired, namely, (1) de- 

 struction of all disease-producing bacteria and a reduction of the total 

 bacterial count of the milk; (2) economy in the use of heat, power, 

 and labor. Unless the first is accomplished the second is of little 

 account. 



2 For information on testing milk, plant operators are referred to Bureau of Animal Industry Circular 

 A-12, "Chemical Testing of MUk and Cream," which may be obtained from the Superintendent of Docu- 

 ments, Government Printing Office, Washington, D. C.j for 10 cents; stamps not accepted. 



