20 GLASS APPARATUS IN COMMON USE 



7. Drain off the water and immerse tubes in a large 

 jar containing water acidulated with 2 to 5 per cent, 

 hydrochloric acid. Allow them to remain there for 

 about fifteen minutes. 



8. Remove from the acid jar, drain, rinse thoroughly 

 in running water, then with distilled water. 



9. Invert the tubes and allow them to drain com- 

 pletely. 



Dry the tubes and polish the glass inside and out 

 with a soft cloth, such as selvyt. 



Infected flasks, plates, and capsules must be treated 

 in a similar manner. 



Flasks which have been used only in the preparation 

 of media must be cleaned immediately they are finished 

 with. Fill each flask with water to which some soap 

 powder and a few crystals of potassium permanganate 

 have been added, and let boil over the naked flame. 

 The interior of the flask can then usually oe perfectly 

 cleaned with the aid of a flask brush, but in some cases 

 water acidulated with 5 per cent, nitric acid, or a large 

 wad of wet cotton-wool previously rolled in silver sand, 

 must be shaken around the interior of the flask, after 

 which rinse thoroughly with clean water, dry, and 

 polish. 



Infected Pipettes. 



1. Plunge infected pipettes immediately after use 

 into tall glass cylinders containing a 2 per cent, solu- 

 tion of lysol, and allow them to remain therein for 

 some days. 



2. Remove from the jar and drain. Boil in water 

 to which a little soap has been added, for thirty 

 minutes. 



3. Rinse thoroughly in cold water. 



4- Immerse in 5 per cent, nitric acid for an hour or 

 two. 



