AND THEIR ESSENTIAL OILS. 33 



although both pale-coloured and specifically light, yet have 

 a specific difference, E. regnans being the more fissile. 

 Then, again, their ecology is not in accord, for each seems 

 restricted to its one particular geological formation, and 

 K. rtgnans is found near water and damp grounds or 

 sides of gullies, whilst E '. fastigata favours a dry hillside 

 locality. The two are also chemically distinct. 



Habitat. E. regnans, so far as our observations go, is 

 restricted to Victoria and Tasmania. 



CHEMISTRY. 



Essential Oil. This material was collected on Mt. Wel- 

 lington, Tasmania, in July, 1908. One sample of leaves 

 with terminal branchlets was collected at a height of about 

 2000 feet above sea-level, and another at about 2500 feet. 

 This tree is known locally in Tasmania as " Swamp Gum/' 

 The oils from both consignments were alike, showing that 

 a difference in altitude has little influence on the secreted 

 oil. The composition of the oil was also in agreement 

 with that of E '. regnans, from material kindly sent for dis- 

 tillation from Yarra Junction, Victoria, by Cuming, 

 Smith, and Company. This is shown from the appended 

 results, and is particularly marked with those derived 

 from the several fractions. The comparative absence of 

 dextro-rotatory pinene in the oil of E. regnans shows it to 

 be a species distinct from E. fastigata, irrespective of 

 botanical differences. 



The oil of E. regnans consists largely of the terpene 

 phellandrene, and contains a fair quantity of the stearop- 

 tene eudesmol. This substance was obtained in larger 

 amount than is usual, by increasing the pressure of steam 

 considerably, after the oil had distilled off in the usual 

 manner, and allowing the distillate to remain for some 

 hours in open vessels ; it could then be removed as a 

 crystalline fat-like mass from the surface of the water, 

 and purified in the ordinary way. 



The presence of eucalyptol was doubtful in the portion 

 distilling at about 176C., so that this frequent constit- 

 uent in Eucalyptus oils is only present in traces in that 

 of E ' . regnans. The ester appears to be almost entirely 

 geranyl -acetate, as it saponified readily in the cold, ani 

 the ketone piperitone is also present in small amount. A 

 considerable portion of the oil consists of high -boiling con- 

 stituents, probably a sesquiterpene largely ; and this high- 

 boiling portion soon became solid in the bottle, caused by 

 the presence of eudesmol. 



