80 



A. — Examination of whole milk and market milk : 1. The 



milk is well mixed and poured into a cylinder, care being taken 

 that the milk runs slowly down its sides, by holding^it in a some- 

 what inclined position. Thus the formation of foam, which would 

 materially interfere with accurate readings, is prevented. 



2. The thermometer remains in the milk for about two minutes 

 before the temperature is quickly read and noted. If the milk be 

 fresh from the cow, it should be cooled by holding the cylinder 

 containing it in cold water. The thermometer is thereby used for 

 stirring the milk slowly, and for observing the gradual reduction 

 of temperature, which is brought as near as practicable to 15° C. 

 (59° F.) If, on the other hand, the temperature of the milk, as 

 during winter time, is very low, it must be gradually raised to 

 from 15 to 20° C. 



3. The stem of the lactodensimeter, which bears the scale, is, 

 to prevent adhesion and to enable a more accurate reading, drawn 

 between the closed lips, and then inserted into the milk until its 

 surface reaches the degree marked 30. It is then liberated to find 

 its level. If it should swim without changing its position, it is 

 pushed from one to two degrees deeper, and again liberated to find 

 its level. If the same reading is obtained, the degree is noted. 



4. All readings of the lactodensimeter give accurate density 

 only at a temperature of 15° 0. "Warmer milk is lighter ; colder, 

 on the contrary, heavier. If the densitj' has been observed at an- 

 other temperature, the actual density is found in the following 

 first table for whole milk, by using it in the following manner : 



The first vertical column of figures gives the degrees of the 

 lactodensiraeters read directly. The first horizontal line gives the 

 degrees of the Fahrenheit thermometer, the second the correspond- 

 ing degrees on the Celsius thermometer. In order to find the real 

 density, we pass from the degree of the lactodensiraeters read, to the 

 right, until we, reach the column headed by the degree of tempera- 

 ture observed. The figure at the intersection of both lines gives 

 actual density at 15° C. If, for instance, we found 28° on tlie 

 lactodensimeter, at 18° C, we would thus find actual density at 

 15° C. = 28.6° = to a specific gravity of 1.0286. 



