REFRACTIVE INDICES WITH OTHER DATA OF EUCALYPTUS OILS. 39 



and only be bestowed on a generation yet to be born ? With 

 all respect to the eminent specialists forming the scientific 

 staff of the British Museum, we feel sure that these manu- 

 scripts must contain observations which can only be fully 

 interpreted and appreciated by Australians. 



The REFRACTIVE INDICES, with other DATA, of 

 the OILS OF 118 SPECIES OF EUCALYPTUS. 



By Henry G. Smith, f.c.s., Assistant Curator, 

 Technological Museum, Sydney. 



[Read before the Royal Society of N. 8. Wales, August 2, 1905.'] 



This work has been undertaken to determine whether 

 results of value could be obtained by the investigation of 

 the physical constants of eucalyptus oils in this direction. 

 The oils worked upon have — with a few exceptions, added 

 under particular species for comparison — all been distilled 

 at the Technological Museum, from material which was 

 botanically investigated by my colleague Mr. R. T. Baker, 

 f.l.s., before distillation. All the specimens were thus 

 authentic and true to name. The whole of the oil contained 

 in the leaves was distilled over as far as possible, and not 

 the more volatile constituents only, which result can be 

 largely accomplished by regulating the method and time 

 of distillation. The richer commercial oils of E. polybractea 

 under No. 22 have been thus obtained. 



The general results, concerning most of this material, 

 have already been published by Mr. Baker and myself in 

 our work "Research on the Eucalypts and their Essential 

 Oils," Sydney 1902, so that this paper may be considered 



