158 CLEAN MILK 



To consider this matter more in detail, especially in regard to 

 the price a given quantity of milk will bring if sold in different 

 forms, suppose we take, for example, 290 gallons of milk. A gallon 

 of milk weighs 8.66 pounds, 290 gallons of milk will then weigh 

 approximately 2,500 pounds, and, containing 4 per cent, of fat, will 

 give us 100 pounds of fat. In converting this into butter the first 

 process will be to skim the milk in a separator, which will give us a 

 loss at the creamery of 0.1 per cent, fat in the skim milk. The skim 

 milk may be assumed to be 85 per cent, of the whole milk; 85 per 

 cent, of 2,500 pounds equals 2,125 pounds skim milk; 2,125 mul- 

 tiplied by 0.001 equals 2.12 pounds of fat in the skim milk. Sub- 

 tracting this from the 100 pounds of fat in the 290 gallons of milk 

 gives us 97.88 pounds of fat in the cream arising from this amount 

 of milk; 326 pounds of 30 per cent, cream will contain just about 

 this amount of fat, that is, 97.8 pounds. In churning this into 

 butter there will be a loss of 0.3 per cent, of the total fat in the 

 buttermilk. The amount of buttermilk is the difference between 

 the weight of the cream and the fat in the cream, or, roughly, 10 

 per cent, of the whole milk. In 326 pounds of 30 per cent, cream 

 there are 97.8 pounds of fat; subtracting this from the weight 

 of the cream gives us the weight of the buttermilk, 228 pounds; 

 multiplying this by 0.003 equals .684 pounds, or the loss of fat 

 in buttermilk; subtracting this loss of fat in buttermilk from the 

 fat in the 30 per cent, cream gives us 97.12 pounds of fat for 

 butter. This would make 117 pounds of butter containing 83 per 

 cent, of fat. (To arrive at this result we divide 97.12 by 0.83, 

 equals 117.) Then, -to get the (theoretical) overrun, we subtract 

 •the 100 pounds of fat in the original milk from the 100 pounds of 

 butter made from it (117), which gives us 17 as the percentage 

 of overrun. We will, however, have mechanical losses equal to 

 2 or 3 pounds, so we will consider that we shall actually get 114 

 pounds of butter from 290 gallons of 4 per cent. milk. The cost 

 of making a pound of butter varies from four cents to a fraction 



