72 



THE GERMICIDAL ACTIVITY OF THE EUCALYPTUS 



OTLS. Part i. 



By P. G-reig-Smith, D.Sc., Macleay Bacteriologist to the 



Society. 



(With one Text-figure). 



Eucalyptus oil is generally considered to have some disinfect- 

 ing properties, but, as a disinfectant, it has gone out of fashion. 

 The reason for its scanty recognition at the present time is 

 probably to be found in the greater ease with which solutions 

 or emulsions of the coal-tar products and of other disinfectants 

 can be made. Eucalyptus oil does not dissolve or emulsify 

 readily, and, on standing, gives a floating film, all of which 

 militate against its use. Added to this, there is the uncertainty 

 about its activity. It finds a place in certain ointments, such as 

 Unguentum Eucalypti and the paraffin-preparation recently 

 devised for spraying burns; but, in these, its action as a cuta- 

 neous stimulant is probably more considered than its value as a 

 bactericide. Again, in ailments of the respiratory system, Euca- 

 lyptus oil is used in combination, as, for example, with menthol. 

 The popular idea is that it acts as a disinfectant, but the medical 

 opinion is that it acts as an indirect expectorant. 



The chemistry of the Eucalyptus oils has been extensively 

 investigated by Baker and Smith, who possess a large number of 

 oils of undoubted botanical origin, and, in view of the uncertainty 

 of the disinfecting action of the oils, it seemed opportune to 

 examine their activity while the material was available. The 

 possibility of finding a trade oil of good quality, with a high 

 disinfecting power, was worthy of some investigation; and, upon 

 consulting Mr. H. G. Smith, he kindly offered to supply me with 

 specimens from the material collected by Mr. Baker and himself. 



The Eucalyptus oil of the text-books upon Materia Medica is 



