248 ODOROGRAPHIA. 



(a) Diluting with the fraction of amygdalina oil : — 



PARTS. PARTS. 



75 eucalyptol, 25 diluent, froze hard ... ... — 20° "5 C ( — 5° F) 



70 „ 30 „ froze — 20°-0 C (— 4° F) 



66-25 „ 32-75 „ „ _20°-5 C (— 5° F) 



62-5 „ 37-5 „ doubtful — 21°-0 C (— 6° F) 



50 „ 50 ,, would not freeze ...— 21°-0 C (— 6° F) 



(h) The results with alcohol were of a very similar character : — 



PARTS. PARTS. 



75 eiicaljpto], 25 alcohol, crystallised readily ... — 16°-5 C ( + 2° F) 



70 „ 30 „ froze — 18°-3 C ( + 1° F) 



65 „ 85 ,, froze with dit!iculty... — 19°-5 C (—3° F) 



60 ,, 40 ,, would not crystallise. 



The deductions from these experiments would seem to be that the 

 process of freezing permits of a very large proportion of the 

 eucalyptol remaining in the oil, the mother liquor of the crystals 

 containing still somewhat more than 60 per cent, of its weight of 

 true eucalyptol. So that though when combined with fractionation 

 this process is extremely useful for distinguishing between oils 

 rich and poor in this constituent, it will not serve as an accurate 

 process for estimating the amount of eucalyptol the oil contains, 

 though by making a correction for this eucalyptol in solution in 

 accordance with the above results, a better approach to accuracy 

 will be obtained." 



The essential oils of Eucalyptus wxre first brought into 

 prominent notice by Mr. J. Bosisto, of Melbourne, and are now 

 employed for a great variety of purposes. An essential oil is 

 produced in greater or less quantity by different species of 

 Eucalyptus, the properties of the oil varying with each, but data 

 determined from Australian distilled oils cannot be relied on, 

 leaves of different species being mixed in the still. 



A useful contribution to the natural history of the Eucalpti is 

 given by A. W. Howitt,* who enumerates nearly fifty species, 

 natives of Gippsland. He classifies them under a number of types, 

 giving the botanical characters of the various groups and of the 

 more important species. Howitt states that the eucalypt forests 

 have greatly increased in extent since the first settlement in 



* Trans. Royal Soc. Victoria, ii., pt. 1. 



