248 .. Elementary Principles of Agriculture 



places easily at the disposal of every farmer a means 

 of determining the butter-producing qualities of every 

 cow in the herd. The success or failure of the farm dairy 

 to yield a profit on the outlay for land, building, feed 

 and labor, lies in the proper selection of the cows to 

 compose the herd. 



351. The Babcock Test is a simple means of testing 

 the milk to determine the amount of butter-fat (rich- 

 ness) contained in a sample of milk. It takes its name 

 from Professor Babcock, of the University of Wisconsin, 

 who discovered the method of making the test. By its 



use the dairyman may learn which 

 of his cows pay for their board. 

 The milk from each cow is 

 weighed, and a small sample used 

 to determine the per cent of but- 

 ter-fat. Knowing these two facts, 

 the total butter-yield for each cow 

 may be calculated. In this way 

 the value of the cow is definitely 



Fig. 160. Apparatus used 



in making the Babcock known. It is easier and more 

 test ' reliable than a "churning test." 



In making the test, a measured quantity of milk is put 

 into a special flask (Fig. 160), and to this a small 

 quantity of acid is added. By following a few simple 

 operations, for which directions come with every 

 machine, the per cent of butter-fat is read off directly 

 on the graduated neck of the bottle. Knowing the 

 per cent of butter-fat and the quantity of milk, the 

 amount of butter in each cow's milk may be quickly 

 calculated. 



352. How Dairy Cows Are Valued. The dairy cow 

 is valuable according to her ability to convert farm feeds 



