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. 
1. Detection of Abnormal Milk through the Senses.—In order 
to detect the different kinds of defective milk, one must be 
Fic. 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 
