338 



CREAM SEPARATION 



If one wishes to know, for example, how much cream should 

 be added to 10 gallons of skim milk to make a 20 per cent cream, 

 one figures as before. 22 : 20 : : 10 : x. This gives 9.09 gallons, 

 as may be proven thus : 



.42 X 9.09= 3.82 

 00 X 10 = 0.00 



19.09 ) 3.820 ( .20 per cent of fat 

 3.818 



20 



Or, reversing the proposition, if one has a 10-gallon can of 

 42 per cent cream and wishes to know how much skim milk to add 

 to it to reduce it to a 20 per cent grade, one figures 20 : 22 : : 10 : x. 

 X ^= 11 gallons, which will be found suflicient. 



Example 8. — Given milks carrying 3^ and 5 per cent fat to 

 be mixed to make 1 per cent milk : 



(5 — 4 = 1) 



(4_3% = y,) 



% : 1 : : 1 : 2. Hence one can of the lower and two of the higher 

 grade will make three cans of the 4 per cent gTade. 



Any other figures may be Tised as desired; as, for example, 

 4.G and 3.:3 to make a 3.7 per cent grade. 4.r) — 3.7 = 0.9 

 3.7 — 3.3 = 0.4. Eour parts of the higher grade and nine 

 parts of the lower are called for. 



Another rerij convenient tool in this connection is a rule by 

 means of which one may find directly how many gallons (or 

 pounds) of rich cream and skim milk will be required to pro- 

 duce any definite mmiber of gallons (or pounds) of cream test- 

 ing any definite percentage of fat. The rule is : Multiply the 

 amount of cream desired by, the test of the cream desired and 

 divide this product by the test of tlie rich cream at hand. This 



