600 ANNUAL REPORT OF THE Off. Doc. 



Of the amouut of fat contained in the whole milk at the start, 

 98 per cent, went ioto the cream and 2 per cent, into the skim-milk, 

 0.75 per cent, into the buttermilk and the same amount was lost 

 mechanically, while 96.5 per cent, went into butter. The total per- 

 centage of loss was 3.5 per cent, of the fat originally in the milk. 



43. Relation of Fat in Milk to Yield of Butter. 



We have seen that it is not milk-serum that produces butter, but 

 it is milk-fat. Hence, if we wish to know the butter-making value 

 of milk, we must' k«ow the amount of fat in milk and then we can 

 tell very closely how much butter should be made from 100 pounds of 

 any particular milk. Now, the question arises: "How much butter 

 should be made for each pound of fat present in milk?" Taking 

 the illustration given in the preceding i)aragraph, we have 1,000 

 pounds of milk containing 4 per cent, of fat, or 40 pounds of milk-fat, 

 and from these 40 pounds of milk-fat we obtain 45 pounds of butter; 

 that is, for each pound of fat in milk, we make one and one-eighth 

 pounds of butter, or just one pound and two ounces. In this case, 

 we made allowances for losses of fat in skim-milk, buttermilk and 

 handling, which ought not to be exceeded in practice, when the dif- 

 ferent operations are carried on with proper skill and care. In 

 general, we may lay this down as a fair rule to follow: Each pound 

 of fat in milk should make one pound and two ounces of finished 

 butter. 



The question may next be asked, "Why do we have two ounces 

 more of butter than we do of butter-fat or milk-fat?" Wliile we lose 

 a little fat in the operation of butter-making, we add to the milk-fat 

 considerable water and some salt and retain a little casein, so that 

 we not only make up for the fat lost but really add more than 

 enough water, etc., to make up the loss. In the illustration above 

 given, we had 40 pounds of milk-fat to start with, we lost 1.4 pounds 

 in various ways in making butter, leaving for the butter 38.6 pounds 

 of fat, and to this amount of fat we added 6.4 pounds of water, salt, 

 etc., and thus obtained 45 pounds of finished butter. From the fore- 

 going considerations, it can be seen that we need only to know the 

 per cent, of ffit in milk in order to calculate the amount of butter 

 to be made from 100 pounds of the milk. It is necessarly only to 

 multiply the per cent, of fat in milk by one and one-eighth or by 

 one pound and two ounces. Thus, we could readily make up a table 

 like the following, covering any range desired: 



