DAIRYING 



51 



Here is an average difference of .1% fat between skimming 

 at 90 degrees F. and 60 degrees F., and if butter fat is worth 

 25 cents per pound, this difference in fat lost amounts to 2y 2 

 .cents per 100 pounds milk skimmed, or $2.50 per day at a factory 

 where 10,000 pounds of milk are skimmed. 



Richness of the Cream. 



312. Many separator bowls are provided with a cream screw 

 by means of which the richness or the thickness of the cream may 

 be changed. This screw can be adjusted so that a thick or thin 

 cream will be separated when the bowl is skimming its normal 

 amount of milk and is running at full speed. A certain amount of 

 variation in the richness of the cream has no effect on the richness 

 of the skim milk and the best separators will skim a cream con- 

 taining 40% fat as well as thinner cream, but fluctuations in the 

 richness of the cream should be avoided. 



313. Most of the standard makes of cream separators will 

 leave as little fat in the skim milk when skimming cream of 20% 

 as 40% fat, but there is some difference in separators on this point. 

 Some of them skim a thin cream with less loss in the skim milk 

 than when rich cream is skimmed. The very rich cream, 50% fat, 

 is successfully skimmed as a rule only when the skimming is 

 done under normal conditions of speed, temperature and capacity. 



Importance of Cleaning a Separator. 



314. Observations of dairy inspectors among users of farm 

 separators indicate that about one-third to one-half are washed 



