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APPENDIX. 



the amount of fluid adhering in the form of drops in a greasy pipette or 

 burette. Should the burette have a glass stopcock this must be greased. 

 Under these circumstances the fluid must always be run out of the burette 

 by the stopcock. If it is emptied by opening the tap and inverting, the inner 

 wall of the vessel is almost certain to become greasy. When this occurs, 



Fig. 49. Fig- 50. 



Author's device for reading burettes. 



A is a draw tube containing a lens B. E is a paper disc 

 pierced with a small hole. The tube C and D are blackened. 

 The whole is fastened to a wooden block, F. This is firmly 

 held to the burette by a clip and spring. By placing the 

 finger in the groove G and pressing with the thumb on H, the 

 tube can be moved up and down until the meniscus is 

 sighted. L is a piece of paper, the lower half of which is 

 blackened. The device is for reading to one-tenth of the 

 ordinary graduations of the burette. The nearest tenth is best 

 obtained by the method described above. 



wash the burette out with water. Fill it with strong (40%) soda. Run this 

 out and then wash it out repeatedly with tap water. Now fill the burette 

 with chromic acid cleaning fluid and allow it to stand over-night. Wash out 

 as before. The burette will now keep free from grease for some time if properly 

 used. 



