109 EUCALYPTUS GLOBULUS 



the tree. When used for medicinal purposes,, the narrow, some- 

 what sickle-shaped ones, which are obtained from the full-grown 

 tree, should alone be used, as it has been shown that these are 

 more efficacious than the broader ovate leaves which are derived 

 from the young plants. The fresh leaves are also more active than 

 the dried. When fresh they have a bitterish, pungent, somewhat 

 camphoraceous taste ; and a peculiar, somewhat camphoraceous, 

 cat-like odour, which is by no means agreeable when evolved from 

 plants growing in a confined space. 



The principal constituent of the leaves is a volatile oil, which 

 may be readily obtained from them by distillation with water. 

 This oil possesses in a marked degree the taste and peculiar 

 odour of the leaves. When freshly distilled it has a yellow 

 colour, but it becomes brown and resinifies by exposure to the 

 air. According to Cloez, it is dextrogyre ; and its specific 

 gravity as estimated by Homeyer, is O8762 at about 54. Some 

 years since Cloez found that the principal constituent of this 

 essential oil was a colourless liquid, boiling at 347, and which he 

 regarded as analogous to camphor, and to which he gave the 

 name of eucalyptol. The more recent investigations of A. Faust 

 and J. Homeyer have shown that this eucalyptol of Cloez is 

 a mixture of two hydrocarbons a terpene and a cymol. They 

 subsequently stated that the essential oil of Eucalyptus Grlobulus 

 contained in addition to these two substances another terpene 

 with a higher boiling point, and a substance containing oxygen ; 

 and in a still more recent investigation J. Homeyer has found the 

 oil to be mainly composed of a terpene and cymene. He also 

 obtained from it a small quantity of another terpene boiling at 

 about 302 (the other terpene having a higher boiling point) ; 

 and an oxidised substance, which the author has termed 

 eucalyptol. 



It was formerly imagined by some that eucalyptus leaves also con- 

 tained quinia or some one or more of the other well-known alka- 

 loids of Cinchona barks. But the experiments of Broughton the 

 government quinologist of Ootacamund, entirely disprove this ; for 

 upon careful examination of the bark and leaves this chemist states 



