257] THE MANUFACTURE OF BUTTER 33 



During the last decade large creameries have attempted 

 to increase the quantity of butter to be made from a given 

 amount of butter fat. The cream that is delivered by the 

 farmer contains a certain amount of fat determined by test- 

 ing. If butter contained nothing else but fat, the finished 

 product should amount to a little less than the quantity of 

 the butter fat in the cream after allowance for wastage is 

 made. In addition to the fat, however, the butter contains 

 water, casein or curd, milk sugar, and other substances. 

 Salt is also added. The presence of these constituents in 

 the butter makes the quantity of finished butter consider- 

 ably greater than the amount of pure fat that it contains. 

 The more water and other substances that can be added to 

 the butter fat, the larger will be the quantity of finished 

 butter. The increase of the finished product due to water 

 and substances other than fat is known as the " overrun ". 

 Expressed as a percentage, the "overrun" is "the per cent 

 which the weight of the constituents other than butter fat 

 is of the weight of the fat in a given quantity of butter ". x 

 In large creameries the amount to be gained from an in- 

 crease of the " overrun " is very considerable, while in a 

 small creamery the gain is of less importance. It was in 

 the large centralizers, therefore, that this matter was 

 given much attention. These large plants get an " over- 

 run " of 21 to 24 per cent, while for the average of ten 

 small creameries in 1904 it was 12 or 13 per cent, increas- 

 ing to 20 per cent by 191 1. 2 



The problem of increasing the " overrun " was soon 

 taken up by various schools and state dairy commissioners, 

 and was discussed in dairy conventions. The State Dairy 



1 Bulletin 164, Bureau of Labor Statistics, U. S. Department of 

 Labor, p. 13. 



2 Ibid. 



