2 9 o THE CHEMISTRY OF DAIRYING 



of water added. F and S are respectively the percentages of 

 fat and non-fatty solids found on analysis. 



looF 

 Percentage of fat removed = 100 



o 



1008 

 Percentage of added water = 100 =r 



When the milk is both watered and skimmed, the formula 

 for the fat removed becomes as follows (W is the percentage of 

 added water) : 



(100 + W)F 



Percentage of fat removed = 100 



o 



In many of the American states the minimum required by 

 law is 9 per cent, of non-fatty solids and 3 per cent, of fat. In 

 some cases it is 9*5 per cent, of the former, and 3*5 per cent, 

 of the latter. 



Causes of Variation. The Channel Island breeds of 

 cows are distinguished above all others by the richness of 

 their milk. That of Jersey cows often contains as much as 

 15 per cent, of total solids, including 5 per cent, of fat. On 

 the other hand, the milk of certain breeds especially those 

 which, like the Fresian Holstein, give exceptionally large 

 yields is generally of inferior quality. The composition of 

 the milk cannot, however, be regarded as characteristic of the 

 breed of cow. The differences are too small, and they are' 

 often obscured by fluctuations due to other causes. The dif- 

 ference in the composition of the milk of two cows of the same 

 breed, apparently normal and similar in all respects, is often 

 greater than the difference observed in the milk of cows of 

 different breeds. 



These remarks may be illustrated by reference to the 

 following figures, 1 which are said to represent the average 

 composition of the milk of various British breeds of cows. 



1 Bell, 



