a 56 CLEAN MILK 



The Overrun. — As an example we will estimate the overrun 

 in making 116 pounds of butter from 2,500 pounds of 4 per cent. 

 milk. We first determine the weight of fat in the milk : 2,500 

 pounds multiplied by .04 equals 100 pounds of fat. Subtracting 

 this from 116 pounds of butter made from it gives us the overrun 

 as 16 pounds, or 16 per cent., because it is 16 per cent, of the ioo> 

 pounds of fat in the milk. 



The overrun is usually less on account of various losses. Thus 

 in skimming the milk in the separator there is a loss of about 0.1 

 per cent, of fat contained in the skim milk; after churning there 

 is the loss in the buttermilk we have noted equal to 0.3 per cent, 

 fat in the buttermilk; and there are the mechanical losses we have 

 referred to, equivalent to about 2 to 5 per cent, of the total fat in the 

 milk. So of the 100 pounds of fat in the 2,500 pounds of 4 per 

 cent, milk there may be only 93.13 pounds of fat available, which 

 would make 110.86 pounds of butter containing 84 per cent, of fat. 

 Subtracting from this 110.86 pounds of butter the 100 pounds of 

 fat contained in the 2,500 pounds of milk gives 10.86 pounds, or 

 10.86 per cent., as the amount of the overrun. The overrun varies, 

 not only owing to the conditions noted, but also as the churning 

 leaves more or less water in the butter, and according to the accu- 

 racy of testing the milk or cream for fat, and in weighing the same. 

 The normal range in overrun for milk varies from 10 to 15 per 

 cent. An overrun above or below these figures demands an in- 

 vestigation. The overrun from cream is somewhat higher than 

 these figures, since there is no loss from skimming, as from milk. 

 The cream overrun varies from 16 to 20 per cent. 



Estimation of the overrun is not in any way essential in cal- 

 culating the money due patrons of a creamery for milk or cream. 

 The simplest, fairest, and generally most satisfactory way is to 

 weigh and test each sample of milk or cream of the patron's for 

 butter-fat and subtracting the cost of making the butter from its 

 selling price, to give the balance of the returns to the patrons in 



