ILLINOIS STATE DAIRYMEN'S ASSOCIATION. 205 



The butter fat is the lightest part of the mixture 

 in the bottle, and consequently is thrown toward the 

 center and accumulates in the neck where it is easily 

 measured. The use of the milk testers is so simple 

 and so satisfactory that it has been well said that 

 every person who has one immediately appoints him- 

 self a committee to tell his neighbor about it. 



One feature of my work at the Agricultural Experi- 

 ment Station, Champaign, 111., has been to make com- 

 parisons of results obtained by these testers with what 

 is called a gravimetric chemical analysis of the same 

 samples of milk. 



These comparisons have shown a very satisfactory 

 agreement, and after some practice a person becomes 

 expert enough to test the quality of milk very accur- 

 ately. A record of observations and precautions use- 

 ful for making tests has been published in bulletins of 

 this station. One of the most important points to 

 watch is the proper strength of the oil of vitriol used. 

 The bottle containing it must be tightly closed, as it 

 will become too dilute by absorbing water vapor from 

 the air, if left; uncorked. 



Since this new mill test has been demonstrated to be 

 of so much practical value to creameries, city milk 

 inspectors and dairymen, a number of minds have 

 been Avorking on the problem of saving time by 

 decreasing the number of tests. 



It is hardly practicable to clium the cream from the 

 milk of each cow in a herd, in order to weed out the 

 unprofitable butter cows. Testing each cow's milk 

 shows the percent, of butter fat in it and a test can 

 be quickly made. When this method of testing each 

 cow's milk is considered, the question at once arises, is 

 it necessary to test the milk given at each milking, and 

 for how long a time ? 



