Grade 

 Date • 



(16) 



EXERCISE 2. 



Object. — To determine the accuracy of the 

 calibration of the glassware used for the 

 Babcock test. 



Apparatus. — Set of bottles used for test, and 

 burette. Sheet of filter paper. 



Step 1. Burette Method. — Fill the bottle to be 

 tested to the zero mark with water. By 

 means of a strip of filter paper remove 

 any water adhering inside the neck above 

 the zero mark. Measure into the bottle, 

 from an accurate burette, 1 cc. of water. 

 If the bottle is correct this should bring 

 the water to the 5 per cent mark. Another 

 cc. from the burette should bring the 

 water to the 10 per cent mark. 



In case of the cream bottles, if 9 gram 

 bottles are used, 1 cc. of water will fill the 

 bottle to the 10 per cent mark, or 5 cc. to 

 50 per cent mark. 



Test all bottles by this method, re- 

 cording all data. 



Step 2. Accuracy of the Pipette. — Allow 17.6 cc. 

 of water from the burette to run into a 

 pipette, the bottom of which is closed 

 with the finger. If correct the water will 

 be at the 17.6 cc. mark. 



Any glassware showing more than .2 

 per cent error should not be used. 



Whole milk bottle. 



17.6 cc. pipette 

 for milk. 



