80 BUTTER-MAKING. 



upon the judgment of the receiver, and in a great measure 

 upon the local conditions. Some of the creameries have no 

 facilities for handling different grades of milk, and some sell 

 butter on a market where no sharp distinction is made between 

 good and poor butter. Others have, through experience, sat- 

 isfied themselves that under American creamery conditions 

 it does not pay to make too many grades, nor does it pay to 

 grade too closely. Two, or at the most three, grades of but- 

 ter can at times be manufactured in one creamery profitably. 

 It is advisable to reject sour and abnormal milk. If accepted, 

 it should not be mixed with the remainder of the milk, as it 

 might contaminate all of it; or, the sour milk might cause 

 coagulation, and thereby clog up the separators. If a can of 

 milk is sour, but otherwise clean, it is not necessarily unfit 

 for the production of first-class butter. If retained until after 

 the sweet milk has been skimmed, it may be run through 

 the separator successfully, 



2. The Use of Acid Tests. — Some creameries, especially 

 the larger central cream plants, are now grading the milk or 

 cream according to the amount of acid it contains. For instance, 

 cream or milk containing .2% acid or less is classed as first 

 grade; that containing from .2 to A'^[q as second grade, and 

 the cream containing more than .V^(_ acid as third grade. 

 Mann's and Farrington's acid tests can both be used, but a 

 more rapid and convenient way is to use a solution prepared 

 from Farrington's tablets. The solution is prepared by taking 

 one tablet for each ounce of warm water and allowing the 

 tablets to dissolve. A^'hen one part of this alkaline solution 

 and one part of milk are put together in a cup and mixed 

 and the solution still retains a pink color, it shows that there 

 is less than .1% acid in the sample tested. If two parts of 

 alkali and one part of milk are mixed and the mixture remains 

 pink, then there is less than .2% of acid. If the mixture turns 

 colorless, it shows there is more than .2% acid in the sample. 

 If three measures of alkali to one measure of milk are taken, 

 and the mixture remains pink, that indicates that there is 



