60 MARKET DAIRYIXG 



stituting for C and D in the above problem we have 60— 

 24 = 36, the amount of skim-milk to be used. 



The same formula may be used to reduce milk to a 

 lower percentage of fat by adding skim-milk. 



Enriching Cream and Milk by Extracting Skim= 



milk. If milk and cream are too low in fat, they may 



be made richer by extracting skim-milk according to the 



following formula : 



AXB . 

 Formula: X = A — — ^ , m which 



X = number of pounds of skim-milk to be extracted. 



A ^= number of pounds of original milk. 



B = test of original milk. , 



C = test desired. 

 Problem: How many pounds of skim-milk must be 

 extracted from 450 pounds of 4.0% milk to raise the test 

 to 4.5%. 



Substituting in the above formula we have 



/ 450 X 4-0 \ 



X = 4So— I — — I =50, the 



number of pounds of skim-milk to be extracted. 



The same formula may be used to enrich cream by ex- 

 tracting skim-milk. 



Mixing Two Milks or Two Creams, or Milk and 

 Cream, of Different Richness. In the preceding two 

 formulas the test of the skim-milk was considered zero. 

 When milks or creams of different tests are mixed the 

 calculation becomes more difficult. Pearson, however, 

 has devised a method by which calculations of this kind 

 are very much simplified. This method is as follows : 



Draw a rectangle with two diagonals, as shown below. 

 At the left hand corners place the tests of the milks or 

 creams to be mixed. In the center place the richness 



