STANDARDIZATION OF CREAM. 263 



47. When whole milk is used instead of skim-milk. 



The following rule and problem will illustrate the 

 methods employed when whole milk is used instead 

 of skim-milk for diluting cream: 



Rule III. Divide the difference between the test 

 of the original cream and the desired test, by the 

 difference between the desired test and the test of 

 the milk to be used, and multiply the quotient by 

 100. 



Problem: 1,000 lbs. of cream testing 30 per cent 

 is to be reduced to 25 per cent by the addition of 

 whole milk. How many pounds of milk testing 4 

 per cent must be added to give the desired test? 



Solution : 



30—25=5; 25— 4=^21 ; 5^21::=.238 lbs. of 4% 

 milk to be added to every one lb. of 30% testing 

 cream. To 1,000 lbs. 30% cream must be added 

 .238X1.000=238 lbs. 4% testing milk. 



48. Standardizing whole mUk. 



The principles involved in the foregoing problems 

 may also be applied in standardizing milk, except 

 cases where skim-milk or cream is to be extracted. 

 A few problems will be sufficient to show the meth- 

 ods which can be employed. 



The following rule may be employed when the 

 milk is too low in per cent of butter fat and it is 

 necessary to determine how many pounds of skim- 

 milk must be extracted to produce the desired per 

 cent of butter fat in the milk. 



(a) Rule : Divide the per cent of butter fat in the 

 milk by the per cent of butter fat desired ; multiply 

 the quotient by the original amount of milk and the 



