13-54 Securing (he Apparatus After Com- Clean the table, and wash and dry all beak- 



pleting the Titrations. — After the analyses of ers, flasks, magnetic stirring bars, and other 



a station have been completed, or a day's 2;lassware used, 



work has been finished, the apparatus must be 13-55 Maintenance and Repair of Ap- 



secured. The pipette and the burette will paratus. — The Winkler titration apparatus re- 

 stay clean longer if they are kept filled when quires little maintenance except for routine 

 not in use. cleaning. The hydrochloric acid will cause 

 Rinse and fill the pipette with distilled water. rubber to deteriorate over an extended period. 

 Fill the burette with sodium thiosulfate solu- so if rubber stoppers are used they may have to 

 tion and check to see that there are no air bub- be replaced infrequently. Rubber tubing 

 bles. Apply a pinchclamp to the tubing from should be replaced when there is evidence of 

 the sodium thiosulfate solution bottle. cracking or wear. 



H. O. 607 137 



