202 REPORTS ON THE STATE OF SCIENCE. — 1916. 



oils in several species of the ' peppermint ' and ' ashes ' groups. 

 Tasmanol is a liquid ; it contains a methoxy-,group and gives a 

 characteristic colour with ferric chloride. It is usually associated with 

 the ketone piperitone. The prepared oils from all the members of the 

 groups mentioned are water-white, so that a possible reason is suggested 

 for the occurrence of the two classes of Eucalyptus oils, those which 

 are colourless and those tinged yellow. 



The botanical characters of the species yielding oils which contain 

 Tasmanol are also in agreement with this chemical character; thus 

 the anthers are kidney-shaped (Renantherce) ; the lanceolate leaves have 

 the venation type 3,* the timbers are white in colour, while the per- 

 sistent portion of the fibrous barks is either that known as ' pepper- 

 mint ' or allied to this ; the kinos contain neither Eudesmin nor Aroma- 

 dendrin. 



The presence or absence of cineol in the oils appears to have no 

 directing influence, as oils equally rich in cineol may contain either 

 phenol or perhaps both. 



The second phenol, which occurs in the other large group of oils, 

 has now been isolated in sufficient quantity to demonstrate its crystal- 

 line form. The accompanying photograph shows the crystals of natural 

 size. These crystals were obtained from the phenol extracted from 

 about 60 lb. of the crude oil of Eucalyptus Woollsiana. 



It would be necessary to treat several hundreds of pounds of oil 

 of the appropriate species to obtain sufficient of this crystallisable 

 phenol to enable its chemical composition to be determined. It does 

 not, so far, appear that it contains a methoxy-group ; in this respect 

 it differs fi'om Tasmanol. 



The crystallisable phenol is associated with the aldehyde Aroma- 

 dendral in the oils of the typical ' Boxes,' the group to which Euca- 

 lyTptv.s Woollsiana belongs ; piperitone is absent ; it possibly occurs 

 also in the cineol-pinene oils from which both the ketone and the 

 aldehyde are absent or only present in traces. 



(b) The Variation in the Amount of Constituents in Eucalyptus Oils 

 in Material of Various Ages. 



Thei'e has long been some uncertainty on this point; it is now 

 recognised, however, that the various products from particular species 

 of Eucalyptus are remarkably constant from a chemical point of view, 

 so much so that botanical diagnosis is assisted by their determination. 



Differences in the amounts of the oily constituents of particular 

 species are, however, to .be expected, although in the case of Eucalypts 

 the variation is but slight, particularly when the material has been 

 collected as for ordinary distillation. This fact is now recognised 

 commercially and standards have been founded upon it. 



Eucalyptiis Smithii, the species chosen for these experiments, 

 affords results from which a very good idea can be formed of ilie extent 

 of variation to be expected in oils from trees of different ages. 



* ^Jiese types -of venation are illaatrated in the first Report. 



