326 GERMICIDAL ACTIVITY OF EUCALYPTUS OILS, ii., 



Table vi. B. co/i communis. 



The relative activities of the two oils were very much the 

 same. One must believe that distillation had no influence upon 

 the hitherto observed higher efficiency of the steam-rectified oils. 



Superheated steam has likewise no action, as was shown by 

 an experiment in which the crude oil of E. cinerea (acidity = 12°) 

 was, with the addition of a few drops of water, sealed in glass 

 tubes and heated at 180° for an hour. Control tubes were sealed 

 at the same time. Six weeks afterwards, the tubes were opened 

 and the oils centrifugalised and examined. The heated oil was 

 found to be slightly more germicidal, but not sufficiently so to 

 warrant the idea that any tangible increase had actually been 

 obtained. 



It may be remembered that, when testing the activity of the 

 oils in solution of olive oil, E. cinerea was found, after the addi- 

 tion of acetic acid, to become more and more germicidal in course 

 of time. Small quantities of the treated oils remained, and that 

 to which the least quantity of acetic acid had been added, was 

 tested in aqueous dilution. 



