82 VARIATION OF FAT IN MILK AND CREAM 



controlled by the creamcrjTnan, who receives the cream after it 

 has been separated. It is physically impossible to produce 

 cream of exactly the same richness from flifferent skimmings 

 under the gravity method of creaming. It is impossible to so 

 operate the spoon, ladle or skimmer as to remove the same 

 amount of skim-milk with the cream each time. Where the 

 skim-milk is drawn from the bottom of the can it is equally 

 impossible to so gage the operation as to leave cream of the same 

 richness in the can at each skimming. Gravity cream, or cream 

 obtained by gravity skimming, is sure to vary in richness, and it 

 is not diiTicult for the producer to realize the causes of variations 

 under this method of creaming. It is more difficult, however, 

 to convince him that the richness of the cream will varj- where the 

 small centrifugal or farm separator is used. The separator is one 

 of the most perfect pieces of farm machinery in use, and is 

 accordingly expected to do nearly perfect work. It is only 

 reasonable that the user of the small centrifugal machine will 

 expect to produce a uniform quality of cream; hence, when he 

 sells this cream and finds that the test is not the same as it was 

 on the previous day he suspects that something is wrong. The 

 small farm separator does produce the same richness of cream 

 from different skimmings, provided that it is adjusted properly, 

 that it is operated in strict accordance with directions which 

 accompany it, and that the richness, condition and temperature 

 of the milk, and the proportion of water or skim-milk used in 

 flushing the bowl to the amount of milk separated, are the same. 

 The following are the chief factors which influence the per cent 

 of fat in cream: 



(i) Cream screw adjustment. 



(2) Richness of milk. 



(3) Rate of inflow. 



(4) Speed of machine. 

 (3) Temperature of milk. 



(6) Amount of water or skim-milk used to flush the bowl. 



I. The Cream Screw.— The richness of the cream obtained 

 from any farm separator is primarily determined and regulated 



