112 LABORATORY BACTERIOLOGY 



Inoculate a tube of bouillon, containing fully 7 c.c, with 6 

 loopfuls from each of these tubes, after the expiration of the 

 following periods of time : i minute, 5 minutes, 10 min- 

 utes, and 30 minutes. In making these inoculations allow the 

 loop to go to the bottom of the inoculated tube. Label each 

 inoculated tube with the strength of the disinfectant and time 

 of exposure and place it in the incubator. It should be noted 

 that the adding of \ c.c. of culture diluted slightly the strength 

 of the disinfectant. 



Note at the next exercise the condition of each inoculated 

 tube. From them the approximate strength and time for the 

 disinfectant to destroy the bacteria can be determined. When 

 this is found the more exact strength and time can be deter- 

 mined by repeating the experiment with weaker dilutions or 

 shorter exposures or both. 



