CHAPTER XII. 



THEORETICAL OVERRUN. 



For the purpose of instructing patrons with regard to 

 the percentage of overrun the following calculation is sub- 

 mitted which incidentally involves the calculation of the 

 amount of skim-milk and buttermilk to be returned from 

 IOC pounds of milk, a calculation with which every but- 

 ter maker should be familiar. 



I. To calculate the amount of skim-milk per lOO 

 pounds of milk. 



Rule: Divide the per cent of fat in milk by the per 

 cent of fat in cream and multiply the result by lOo; the 

 product subtracted from lOO will be the number pounds 

 of skim-milk. 



Example : How much skim-milk is obtained from lOO 

 pounds of 4% milk when the separator delivers a 40% 

 cream ? 



4 -^ 40 = .10, .10 X 100 = 10, 100 — 10 = 90 = 

 No. lbs. skim-milk. 



Corollaries. ( i ) The richer the milk and the poorer 

 the cream the less skim-milk. 



(2.) The poorer the milk and the richer the cream the 

 more skim-milk. 



To allow for variations in richness of cream and small 

 overweights at the creamery, 3 should be subtracted from 

 the calculated amount of skim-milk. Thus in the problem 

 above, the skim-milk should be distributed on the basis 

 of 87 instead of 90 pounds per 100 pounds of milk as 

 calculated. 



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