CHAPTER VII. 



TESTING MILK. 



MlLK varies considerably in its physical and chemi- 

 cal composition, hence the need for testing it. Milk 

 should be examined first with reference to its color, 

 smell, and taste test with the eye, the nose, and the 

 tongue. If the color be abnormal, the smell objec- 

 tionable, or the taste sour or otherwise unpleasant, 

 such milk should not be used in the dairy. 



Among the common testing instruments which 

 have been, or are, in use in the dairy, are : 



1. The Thermometer, which is an instrument for 

 testing temperatures. A reliable thermometer, pre- 

 ferably made of glass, should be found in every dairy. 



2. The Lactometer is used for testing the specific 

 gravity of milk. This should have a thermometer in 

 connection. What is known as Quevenne's is the 

 one most commonly used. It gives the difference 

 between the specific gravity of milk and water in 

 thousandths. The milk should be at a temperature 

 of about 60 degrees. Between 50 and 60 degrees, 

 one-tenth of a degree should be subtracted from the 

 lactometer reading for each degree in temperature 

 below 60 degrees ; e. ^., when lactometer reading is 



48 



