367 



One distinguishing feature with the oil of Eucalyptus Macarthuri is the 

 presence of crystallised eudesmol, a subtsance absent in the oils of both Darwinia 

 and Callitris. 



The following constants are those for a fair sample of the crude oil of 

 Eucalyptus Macarthuri: 



Specific gravity at 15 C. = 0-9174. 



Optical rotation a D -). 0-69. 



Original ester = 68-4 per cent. 



Ester after acetylating (cold saponification) ... 81-02 per cent. 



Refractive index at 20 C = 1-4721. 



Soluble in ij volumes 70 per cent, alcohol. 



In the course of these researches it was found that the acetic acid ester of 

 geraniol was entirely saponified in the cold by two hours' contact with alcoholic 

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

 and leaf oils of Eucalyptus Macarthuri the naturally formed ester varies between 

 60 and 77 per cent., but this variation represents largely the oscillation between 

 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 amount of 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 

 as high as 77 per cent. In one sample containing 74-9 per cent, ester, only 6 per 

 cent, of free 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 of this Eucalypt 

 the ratio ;^ e S io ' has ranged between 80-100 and 90-100. 



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

 Callitris Tasmanica, the ^r^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 

 ^S^mioF 1 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 of the mechanism of 

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



It is characteristic, however, of the Eucalypts generally, for the perfumery 

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

 very young seedling leaves the chief oil constituent of the species is in evidence. 



The time of year also appears to have some influence on the ester formation 

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

 material, so that the oil distilled commercially from cultivated plants of 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 

 naturally, 



