367 



One distinguishing feature with the oil oi Eucalyptus Macarthuri is the 

 presence oi crystallised eudesmol, .1 subtsance ab en1 in the oils oi both Daru inia 

 and Callitris. 



The following constants are those foi a fair sample oi the crude oil oi 

 Eucalyptus Macarthuri : 



Specific gravity at 15° C. ... ... ... ... = 0-9174. 



Optical rotation a D ... ... ... ... ... + 0-69°. 



Original ester - 68-4 per 1 ent. 



Ester after acetylating cold saponification ... = 81-02 per cent. 



Refractive index ai 20 C. ... ... ... ... = 1-4721. 



Soluble in 1 i volumes 70 per cent, alcohol. 



In the t ourse oi these researches it was found that the acetii a< id estei oi 

 geraniol was entirely saponified in the cold by two hours' iMnt.ni with alcoholic 

 potash, the reaction being oi considerable quantitative value. In both the bark 

 and lr.it oils oi Eucalyptus Macarthuri the naturally tunned ester varies between 

 60 and yy per cent., but this variation represents largely the oscillation betv 

 the ester and the free geraniol, consequently when the free alcohol is pronounced 

 the ester is less, and when the ester is at a maximum the minimum amounl oi free 

 geraniol is present. In no instance has less than 60 per cent, of geranyl-acetate 

 been found in the oil of this species of Eucalyptus, although it sometimes reaches 

 a^ high as yy per cent. In one sample containing 74-9 per cent, ester, only 6 per 

 cent. o| tree geraniol was present. Another sample gave 65-8 per cent, ester, and 

 11-5 per cent, free alcohol. Other determinations were in agreement, and in all 

 the analyses we have so far been able to make with the oil oi this Eucalypt 

 ,1 "' ratio < "tSl£Sf B ' has ranged between 80-100 and 90-100. 



With both the New South Wales and Tasmanian samples of the oil of 

 Callitris Tasmanica, the -" e S°' was 78-100. 



It has been found by Charabot and Hebert in their experiments " on the 

 mechanism of esterification in plants," that the maximum ester content obtained 

 with geraniol and acetic acid, by their methods of working, was reached when the 

 ""total ge^of 01 equalled 67-100 ; but as shown above, this naturally formed ester 

 in the oils of these two Australian plants does not fall below 78-100; and 

 occasionally reaches 90-100. It is thus evident that the method whereby this 

 large amount of geranyl-acetate is formed naturally, is not yet known. 



The abnormal leaves which spring from the stumps of the felled trees of E. 

 Macarthuri not only give a greater yield of oil, but the oil itself also contains a 

 greater percentage of ester than does that from old leaves. A sample, distilled 

 from such, collected at Paddy's River, New South Wales, in March, contained 

 77-5 per cent, of ester saponified in the cold with two hours' contact. 



The oil from seedlings has also a high ester content, exceeding, in some cases, 

 70 per cent., while in that from the very early shoots the ester was 75 per cent. 



It is perhaps worthy of note that a predominance of this ester should be 

 found in the oil from the youngest material, and that the trend oi the mechanism of 

 ester formation should show such activitv so early in the life history of the plant. 



It is characteristic, however, oi the Hucalypts generally, lor the perfumerj 

 products peculiar to the species to be formed very early in the plant, and in the 

 very young seedling leaves the chiei oil constituent oi the species is in evidence. 



The lime oi year also appeals to have some influence on the ester formation 

 in the oil oi E. Macarthuri, but to a less extent than the age of the leai 

 material, so that the oil distilled commercially from cultivated plants oi this 

 species should show a high ester content, perhaps, as an average, not less than 

 5 per cent, in excess of that found in the leaf oil collected from old trees growing 

 rial urallv. 



