60 Domestic Science 



topmost graduation. Clamp the burette in an upright 

 position in a suitable stand (Fig. 22). Place the beaker 

 under the tap and allow exactly 5 c.c. of water to run 

 from the burette into the beaker. Close the tap and 

 weigh the contents of the beaker as hi the last experi- 

 ment. Add water from the burette, 5 c.c. at a time, 

 weighing the contents of the beaker after each addition, 

 till the lowest graduation mark on the burette is reached. 

 A properly graduated instrument should show equal 

 increments of weight for each successive* quantity run 

 out, and the weight of each such quantity should be 

 very approximately 5 grams. 



Exercises for Student. 



1. How would you propose to test the accuracy of graduation 

 of a flask constructed to hold 50 c.c. of liquid ? Carry out the test 

 by the method you suggest. 



2. How would you graduate a flask so that it shall contain 

 80 c.c. of water at ordinary temperatures ? Obtain a flask of 

 suitable size and carry out the graduation by your suggested method. 



3. How would you check the accuracy of graduation of such 

 a flask as that mentioned in the previous exercise ? 



Fig. 23. 



33. A weighing-machine, such as one of those used 

 for finding the weight of a person commonly seen in 



