CONSTITUENT OF PEPPERMINT ODOUR IN EUCALYPTUS OILS. 137 



E. Sieberiana, and from E. coriacece and several others. If sub- 

 sequent investigation should show this constituent to have special 

 value for medicinal or other purposes, it can be obtained com- 

 mercially from the leaves of both E. dives and E. radiata, so that 

 the supply can be assured. In the oils of those species mentioned, 

 this peppermint constituent occurs with phellandrene as the 

 principal terpenc, and in many of them with an almost entire 

 absence of eucalyptol. Although occurring principally with 

 phellandrene, yet, this terpene need not necessarily be present, 

 as the peppermint constituent has been found occurring in the oil 

 of at least one species in which phellandrene is quite absent; but 

 generally, it may be stated as occurring in the oils of those species 

 which are pronounced phellandrene bearing ones, and which make 

 such a well denned group of Eucalyptus trees. 



The yield of oil obtained, on a commercial scale, from the leaves 

 and terminal branchlets of E. dives ranges from two to three per 

 cent.; the oil is usually almost colourless, owing to the small 

 quantity of free acid present. The crude oil has a low specific 

 gravity 0882 to 0-888 at 15° C, only a trace of Eucalyptol appears 

 to be present at any time, but there is always much phellandrene. 

 The optical rotation of the crude oil in a 100 mm. tube ranges 

 from — 55*7° to — 639° the higher rotation occurring during the 

 Australian spring months, the lower during the winter months. 



On rectifying a sample of the oil of E. dives distilled in October, 

 only two per cent, distilled below 172° C; between 172° and 

 200° C. 1 60 per cent, was obtained ; between 200° and 227° C. 

 13 per cent, came over, and between 227° C. and 240° C. 20 per 

 cent, distilled. The peppermint constituent occurs in greatest 

 amount in the fraction 227° to 240° C, and it was thus possible 

 to obtain it in a crude condition by ordinary distillation. 



The specific gravity at 15° C. of the fraction 172° - 200° C. was 

 0-8593, of that obtained between 200° and 227° C. 0-8936, and 

 of that between 227° and 240° C. 09318. 



1 These temperatures are corrected to the nearest whole degree. 



