RECEIVING, SAMPLING, AND GRADING. 



79 



milk, it is essential that the milk or cream be graded when it 

 is delivered at the creamery. 



In the grading of milk or cream, different methods can be 

 used for detecting abnormal milk: (1) through the senses, 

 taste, sight, and smell; (2) by the acid tests; (3) by the fer- 

 mentation test; (4) by heating; (5) by the Babcock test and 

 the lactometer. 



I. Detection of Abnormal Milk through the Senses. — In order 

 to detect the different kinds of defective milk, one must be 



Fig. 24. — The Twentieth-century can-washer. 



endowed with acute senses of smell, taste, and sight. When 

 the milk is in a good condition, it has a pleasant smell and 

 sweet taste, and appears normal. If it has a disagreeable 

 smell and taste it cannot produce good butter or cheese. As 

 a rule, the quantity of defective milk brought into the aver- 

 age creamery is much in excess of that of really perfect milk. 

 As a consequence it would not be practical to separate all 

 the defective milk into one class and the perfect into another. 

 The question as to where the line should be drawn between 

 the good, medium, and very bad milk or cream, must depend 



