356 



investigation thai the name Eucalyptol was derived, it being given to the 

 portion of the oil distilling at about 175 C. ; and although, in the light of 

 subsequent research his results were not strictly correct, yet the facts therein 

 submitted are interesting and valuable, particularly for the following reasons :— 



1. He mentions that he obtained the oil from both green and dry 



leaves, and also from material from Melbourne, and that the oil 

 distilled under these different conditions was always similar, 

 thus indicating the practical constancy of constituents in the oil 

 of identical species of Eucalyptus. 



2. On passing hydrochloric acid gas into the oil, he obtained a 



crystalline mass, the liquid portion becoming of a beautiful 

 blue-violet colour. Although Cloez did not follow the matter up, 

 it is now known that this colour reaction was due to the presence in 

 the oil of the sesquiterpene (aromadendrene). This blue-violet 

 colour is always obtained when this sesquiterpene is treated with 

 the halogen acids. 



Homever (Arch. Pharm. (3) v., p. 293), soon after Cloez's research came 

 to very different conclusions on examining 3 kilos of a Eucalyptus oil, the 

 specific gravity of which was 0-8762 at 12° C. This oil had probably been 

 distilled from E. dives or E. radiata, species which were, at that time, looked upon 

 as forms of E. amygdalina. This is probably the first time that a difficulty was 

 experienced in arranging results by different observers on Eucalyptus oils, and 

 was due to the products having been obtained from species belonging to 

 distinct groups of these trees. 



The correct placing of Eucalyptol chemically was due to E. J alms (Ber. 

 17, 2941), who isolated it fairly pure (specific gravity 0-923 at 16 C. and B.P. 

 I76-I77°C), from the compound it forms with dry hydrochloric acid gas. He 

 also showed its analogy with cineol, and that its formula was C IO H l8 0. 



M. R. Voiry (Compt. Rend. 1888, p. 1419) describes a method for the 

 preparation of pure Eucalyptol (cineol) by freezing it out of the oil. He also 

 states that from the oil of E. globulus were obtained both acetic and formic acids, 

 and shows that both butyric and valeric aldehydes also occur. 



Although these aldehydes, which are very irritating when inhaled, are 

 present in most crude Eucalyptus oils, yet, like the other constituents, they occur 

 in varying amounts, being most pronounced in those cineol-pinene oils in which 

 the corresponding esters occur in greatest quantity, such for instance as those 

 of E. cinerea, E. goniocalyx, E. Maideni, &c. 



The presence of both ethyl and amy] alcohols was determined by 

 Bouchardat and Olivier (Bull. Soc. Chim. in. 9, p. 429) in the lower-boiling 

 portions of Eucalyptus oil. To these may now be added methyl, iso-butyl and 

 normal butyl alcohols which have been determined during these investigations. 



Numerous articles dealing with the special study of several of the 

 constituents of Eucalyptus oils are here appended ; such are those relating to 

 cineol, geraniol, terpineol, piperitol, eudesmol, the monohydric alcohols, the 

 cyclic (aromatic) aldehydes, citral, citronellal, piperitone, the phenols, the free 

 acids, the various esters, the terpenes (such as pinene, phellandrene, terpinene), 

 the sesquiterpene, and the paraffin stearoptene. 



The remaining constituents, also enumerated in the following list, usually 

 occur in small amount, although some of them are quite of frequent occurrence, 

 as, for instance, cymene, and the lower-boiling aldehydes. Although these 

 constituents are not here treated separately, they will be found enumerated 

 under the particular species in the oil of which they occur. 



