106 



CONDITIONS AFFECTING RICHNESS OF CREAM 



slant, three per cent milk produces 20 per cent cream, four 

 and one-half per . cent milk produces 30 per cent cream and 

 six per cent milk produces 40 per cent cream. The correct- 

 ness of this rule is further demonstrated by results of sepa- 

 rator experiments conducted by the Purdue University Agri- 

 cultural Experiment Station, as summarized in table 11. 



Similar results were also obtained by Eckles and Wayman 1 

 and by Guthrie. 2 



It is further interesting to note that the difference in the rich- 

 ness of cream from milk of different per cents of fat increases 

 as the ratio of skim milk to cream becomes wider. This rule is 

 shown in the following figures. 



Table 12. Relation of Richness of Cream to Ratio of Skim 

 Milk to Cream. 



The per cent of fat in the milk separated does not appreciably 

 affect the skimming efficiency, the per cent of fat found in the 

 skim milk from rich and poor milk being practically the same. 



Effect of Speed of Separator on Richness of Cream. The 

 higher the speed of the separator the higher the per cent of fat 

 in the cream. This rule applies in the case of most separators 

 and under most conditions. The influence of the speed on the 

 richness of the cream is largely due to the direct effect of the 

 speed on the ratio of skim milk to cream. 



The higher the speed the greater the centrifugal force and 

 the more rapidly will the skim milk leave the bowl. An increase 

 in speed therefore increases the capacity of the skim milk dis- 

 charge. This, means less milk for the cream .outlet and con- 

 sequently richer cream. A decrease in the speed lessens the 



1 Eckles and Wayman. Factors Affecting the Per Cent of Fat in Cream 

 from Farm Separators. Missouri Bulletin 94, 1911. 



2 Guthrie. Variations in the Tests for Fat in Cream and in Skimmed 

 Milk. Cornell Bulletin 360, 1915. 



