336 GERMICIDAL ACTIVITY OF EUCALYPTUS OILS, H., 



Table xv. B. coli communis. 



Dilutions bactericidal at 20°. 



"" =or weaker. 



Both these oils are good disinfectants; they are the best of the 

 crude oils that have been examined; the reason for their excel- 

 lence is to be found in the presence of the aldehydes, aromaden- 

 dral and citronellal. Indeed, from the work that has been done, 

 it is clear that a comparatively high germicidal activity can only 

 be expected in those oils containing substances of an aldehydic 

 nature. The pinenes and sesquiterpene are, inferentially. pool- 

 disinfectants; cineol is moderate, phellandrene and the ketone 

 piperitone are better, and the aldehydes are the best. 



Subsidiary Notes. 

 a. The races in the stock culture. — During the research, the 

 stock culture of B. coli communis was plated to see if it had 

 retained its purity. The plates showed a pure culture. One of 

 the colonies was picked out and used. As it appeared to be 

 much more sensitive to the action of the Eucalyptus oils than 

 the stock culture, a direct test was made, using the 2nd hour oil 

 of E. australiana. 



