110 



MANUAL OF MILK PRODUCTS 



the properly mixed milk in the weigh can direct into the Bab- 

 cock test bottle. In this way the extra work of handling sample 

 jars and of preparing the milk in the jar for the test is made 

 unnecessary, and all danger of fat separation before the sample 

 reaches the test bottle is avoided. 



Another practice of taking single samples is to take and test 

 samples from every other or every third delivery of milk. At 

 the end of the month or other period of payment, these individual 

 tests are averaged and the pounds of butter-fat are calculated 

 by multiplying the average test by the total pounds of milk 

 received for that period. This practice is obviously less reliable 

 than where single samples are taken and tested daily. How- 

 ever, experimental results indicate that samples taken as often 

 as every third day give results which compare very closely with 

 those obtained from daily samples. 

 Composite samples of milk. 



The purpose of taking composite samples is to reduce the 

 labor and expense of testing. The true composite sample con- 

 sists of aliquot portions of milk of several deliveries from the 

 same patron. 



Fig. 7. — Glass- 

 stoppered milk 

 sample bottle. 



Fig. 8. — Milk sample 

 bottle with metal cap. 



Fig. 9. — Mason 

 fruit jar for milk 

 samples. 



Jars for composite sampling (Figs. 7—9). - 



Composite sample jars must have a tight seal in order to 

 prevent evaporation of moisture. Pint jars sealed with glass 



