EUCAI* YPTUS. 283 



EUCALYPTUS OILS. 



BY S. M. WOODBRIDGE, PH. D. 



Chemical authorities in technical works and encyclope- 

 dias have always divided the oils from the products of 

 growth in two classes : 



1. Fixed or fatty oils, and 



2. Essential or volatile oils. 



The fixed or fatty oils are described as follows : Char- 

 acterized by their ability to communicate to paper and like 

 substances a permanent translucent grease-spot, and the}' 

 cannot be volatilized except by ' ' destructive distillation ' 

 at high temperatures. 



The essential or volatile oils are described as not being 

 oleaginous to the touch and make no permanent grease- 

 spot ; they are distilled at various temperatures, unchanged. 



Accepting these definitions as true, and it does not 

 appear -that they have ever been questioned, it is difficult 

 to see how the oils of the various Eucalypti can be defined 

 under either of the above classes. Of a large variety that 

 have been tried all are unctious to the tou:h but leave no 

 permanent grease-spot on paper nor does it require a 

 "destructive distillation" to volatilize the greater portion 

 of them, although the last portions of all of them that 

 have been tried, require a "destructive distillation; " 

 neither, on the contrary, do they volatilize at ordinary 

 temperature nor volatilize at all unchanged, but a variety 

 of products come over at different temperatures far above 

 the boiling point of water, each of which has very different 

 characteristics from the oil and from every other product 

 obtained. 



