Art. XVI. — Preliminary Survey of Eucalyphis-Oils of 

 Victoria. 



By W. Percy Wilkinson. 



[Communicated by C. E. Blackett, Esq., F.C.S., &c., 

 14tli December, 1893]. 



Only of recent years have the Eucalyptus-Oils, both in their 

 purely chemical and commercial aspects, been receiving the atten- 

 tion they deserve, considering that large tracts of the continent 

 of Australia are covered with forests of the Eucalypts, including 

 more than 134 species (Baron F. von Mueller, 2nd Systematic 

 Census of Australian Plants, Part I., 1889; Eucalyptographia, 

 1879-1884), many of which yield much volatile oil. Hitherto the 

 oils have been investigated almost exclusively in Europe, where 

 however only limited varieties of the oils have been accessible ; 

 so it seemed to me that, as a detailed examination of certain 

 typical oils was being carried out by European chemists, the 

 most advantageous woi'k to begin on in Australia would be a 

 general preliminary examination of the oils from as many 

 distinct Eucalypts as possible. Accordingly eighty -seven samples 

 were gathered (practically all in Victoria), some from the 

 Botanic Garden Museum, some from the Pharmaceutical Society's 

 Museum, and the rest directly from the distilleries, which during 

 the last few years have increased greatly in number. It was an 

 essential part of the inquiry to ascertain the botanical source of 

 as many of the oils as possible, and in a number of cases it has 

 been with great kindness determined by Baron F. von Mueller, 

 our distinguished Government Botanist, on specimens submitted 

 to him. For the purposes of a general preliminary examination 

 it was desirable to select a few definite physical properties 

 capable of exact measurement for defining and differentiating the 

 oils, and the density, specific rotation, refractive index and 

 specific refractive energy were chosen as most suitable \ the 

 boiling points of the oils were not taken, as their range is small, 

 and because the boiling points of mixtures such as these oils is not 

 a satisfactory physical constant. The only chemical test applied 



o2 



