CONSTITUENT OF PEPPERMINT ODOUR IN EUCALYPTUS OILS. 139 



oil of E. hcemastoma, they say, that probably this contains 

 menthone. There appears to be but one constituent in Eucalyptus 

 oils having this peppermint odour. We have distilled the oil from 

 the leaves of E. hcemastoma from two localities and failed to detect 

 this peppermint constituent in the oil. This species grows plenti- 

 fully in New South Wales, and is known as " White or Scribbly 

 Gum." Mr. Smith, the author of this species, named E. hcemastoma 

 in 1797, no doubt from trees growing at Sydney, in the neighbour- 

 hood of which it occurs plentifully, and as the characteristic con- 

 stituents of identical species of Eucalyptus appear to be constant, 

 there can be no doubt that the oil referred toby Schimmel & Co. 

 was not obtained from E. hcemastoma, but from another species. 



The question of constancy of chemical constituents in oils of the 

 same species of Eucalypts will be fully discussed in the forthcom- 

 ing work by Mr. R. T. Baker and myself. 



Now that this peppermint constituent has been isolated it is 

 found not to be menthone, as it has a much higher specific gravity, 

 a higher boiling point, has probably no rotation, and the crystalline 

 product obtained on reduction by sodium in alcoholic solution is 

 not menthol, but quite a distinct substance and most probably 

 new. Its taste and odour also differ from menthone. Jn boiling 

 point and specific gravity it more closely resembles pulegone, but 

 the same differences present themselves as with menthone. We 

 are indebted to Messrs. Schimmel &, Co. of Leipzig for samples of 

 both menthone and pulegone, that firm having presented to the 

 Technological Museum a very fine collection of the several con- 

 stituents occurring in essential oils. It is probable that the 

 peppermint constituent found in Eucalyptus oils is a new ketone, 

 and in the second part of this paper I purpose dealing more fully 

 with its chemical reactions and peculiarities. 



Experimental. 



Purification of the constituent. 

 The fraction 227° - 240° C. was frequently agitated for about 

 three weeks with a saturated solution of sodium bisulphite, adding 



