6o 



MODERN METHODS OF TESTING MILK 



what remains is made in the 

 construction of the pipette. 

 Special experiments having 

 shown that .1 cc. of milk will 

 remain adhering to the inside, 

 the pipette is made to hold 

 17.6 cc. to the mark, but is 

 expected to deliver into the 

 bottle only 17.5 cc., the exact 

 amount required for the test. 

 In delivering the milk, the 

 pipette must never be held 

 perpendicularly in a line with 

 the neck of the test-bottle, 

 running the milk straight 

 down as shown in Fig. 260,, 

 since the narrow neck may 

 easily choke up with milk and 

 run over the top. 



MEASURING AND ADDING 

 ACID 



When the samples of milk 

 are in the test-bottles, the acid- 

 measure (Fig. n, p. 37), is 

 filled to the 17.5 cc. mark and 

 the acid (see p. 43) is poured 

 into the test-bottle. The acid 

 should be at a temperature of 

 60 to 70 F. Much care 

 must be exercised in pouring 



the acid into the test-bottle containing the milk. The 

 test-bottle is held in an inclined position, so that the 



FIG. 26a WRONG WAY OF 



HOLDING PIPETTE AND 



BOTTLE 



