Cream Separation 



1879 



still the skimmed milk will contain approximately the same percentage of 

 milk-fat as when the bowl is revolving at the so-called normal speed. In 

 the case of the hand separators p^"- 



^ cent- 



this amounts to five or ten revo- ^^^ 

 lutions of the crank less than the 

 number given for normal speed. 

 Percentage of fat in whole 

 milk. — The percentage of fat in 

 whole milk is variable. In this 

 respect the milk from individual 

 cows may /ary as much as two or 

 three per cent from one milking 

 to another, and yet the cow may 

 appear to be in a normal con- 

 dition. The fat content of the 

 milk of a herd is not so variable 

 as the fat content of the milk 

 from a single cow. Other things 

 being equal, the larger the herd 

 is, the smaller is the variation of 

 the fat content of the milk. The 

 difference in the percentage of 

 fat in milk is not so great from 

 day to day as it is from milking 

 to milking, and this variation is 

 still less from week to week and 

 from month to month. The in- 

 fluence of a variation in the fat 

 content of the whole milk on the 

 percentage of fat in the cream is 

 shown in Figure 87. The per- 

 centage of fat in the cream is in 

 almost direct proportion to the 

 percentage of fat in the whole 



Percentage 3 4 5 3 4 5 



Separator 1 Separator 2 



Fig. 87. — A diagram representing the percentage 

 of fat in cream as influenced by the percent- 

 age of fat in whole milk. The figures on the 

 left of the diagram rep/esent percentage of fat 

 in cream, and those underneath represent per- 

 centage of fat in whole milk 



milk. 



Variation in the quantity of whole milk or in the amount of liquid used for 

 flushing. — There is a variation in the quantity of milk from one milking to 

 another, and this causes a variation in the amount to be separated from one 

 time to another. There are very few persons operating separators who use 

 a fixed amount of skimmed milk or water for flushing the separator bowl. 

 For the hand machines two or three quarts of flushing material are sufficient. 

 The amount of flushing material that goes into the cream is only a small 



