Eticcxlyptus-Oils of Victoria. 

 Table VIII. 



205 



The colour of the original oil appeared almost all in the first 

 fraction 160 - 170°. The result here is as before to show clearly 

 enough that we are dealing with a mixture of substances, the 

 change in the specific rotation from a fairly large positive value 

 at 160 - 170° to a small negative one at 177 - 179° being specially 

 noticeable as accompanying an increase of density. As the oil 

 was chosen as a typical Cineol-oil, the best method of determining 

 how far a separation had been accomplished was to test for 

 Cineol iu each fraction according to the method of Wallach {Ann. 

 der Chem., 227, p. 280) ; in every case the characteristic unstable 

 splendid prismatic crystals of Cineol di-bromide were formed, 

 readily decomposing on exposure to the air. 



Dry hydrogen chloride also produced in each of the well-cooled 

 fractions white crystals of the unstable Cineol di-hydrochloride. 

 From the results it will.be seen, as in the first type of oil, that we 

 are dealing with a mixture, in which fractionating eflects only a 

 limited separation. 



On account of tl)e difiiculty of separating the two ciiief 

 constituents of Eucalyptus-Oils by fractional distillation, it seemed 

 to be advisable to use the measurements of the physical constants 

 to obtain at least an approximate estimate of the proportions in 

 which they are present. For instance, in the case of the density, 

 if we assume that an oil is composed of /^ parts by weight of a 

 mean Terpene of density •SSd, and /o parts of Cineol of density 



