CLEANING INFECTED TEST-TUBES 19 



5. Run rectified spirits through the pipette and drain 

 as completely as possible. 



6. Place the pipettes in the hot-air oven (vide page 

 31), close the door, open the ventilating slide, and 

 run the temperature slowly up to about 80 C. Turn 

 off the gas and allow the oven to cool. 



Or 6a. Attach each pipette in turn to the rubber 

 tube of the foot bellows, or blowpipe air-blast, and 

 blow air through the pipette until the interior is dry. 



Glassware that has already been used is regarded as 

 infected, and is treated in a slightly different manner. 



Infected Test=tubes. 



1. Pack the tubes in the wire basket of the auto- 

 clave (having previously removed the cotton-wool 

 plugs, caps, etc.), in the vertical position, and before 

 replacing the basket see that there is a sufficiency of 

 water in the bottom of the boiler. Now attach a 

 piece of rubber tubing to the nearest water tap, and 

 by means of this fill each tube with water. 



2. Disinfect completely by exposing the tubes, etc., 

 to a temperature of 120 C. for twenty minutes (vide 



Page 37)- 



(If an autoclave is not available, the tubes must be 

 placed in a digester, or even a large pan or pail with a 

 tightly fitting cover, and boiled vigorously for some 

 thirty to forty-five minutes to ensure disinfection.) 



3. Whilst still hot, empty each tube in turn and 

 roughly clean its interior with a stiff test-tube brush. 



4. Place the tubes in a bucket or other convenient 

 receptacle, fill with water and add a handful of Sapon 

 or other soap powder. See that the tubes are full and 

 submerged. 



5. Fix the bucket over a large Bunsen flame and 

 boil for thirty minutes. 



6. Cleanse the interior of the tubes with the aid of 

 test-tube brushes, and rinse thoroughly in cold water. 



