— 5i — 



This confirms on the whole Mossler's statement that oils rich 

 in eucalyptol have a low, oils poor in eucalyptol a high bromine 

 number. But the method has not been found useful in practice, as 

 it is not safe to estimate the eucalyptol-content direct from the bromine 

 number; for example, oil IV has, in spite of the higher cineol-content, 

 a higher bromine number than oil V, whilst according to Mossier the 

 reverse should be the case. Mossier further established that the action 

 of the bromine on most essential oils shows constant values after six 

 hours; only those oils which, besides adding, substitute much 

 bromine show a pronounced increase of the bromine entering into 

 reaction, when extending the time for reaction; but the values agree 

 completely if the action is allowed to continue for equal times. We 

 found that this view does not apply to eucalyptus oil, with which 

 Mossier unfortunately made no experiments in this direction. After 

 allowing the bromine to act for 20 hours we obtained the bromine 

 numbers, for oil IV 1*89,4, for oil V 267,8, and for oil VI 77, numbers 

 which do not speak for a uniform bromine-action. In view of the 

 varying composition of eucalyptus oils, this behaviour is readily understood. 

 With regard to the general applicability of Mossler's method, 

 we express our opinion in another place 1 ). 



A sample of an oil from Eucalyptus citriodora Hook, of Indian 

 origin, which we received from London, resembled exactly the 

 Australian oils in its properties and composition. We determined the 

 following constants for this oil: d^o 0,8686; «p -j- o°2o'; soluble in 

 5 and more vol. 70 per cent, alcohol; citronellal content 9i,8°/o 

 (determined by acetylation). 



In a treatise on the eucalyptus species, G. Smith 2 ) recommends 

 that more attention should be paid to the cultivation of these trees, 

 and that the results which we possess of the scientific examination of 

 eucalypts and their oils should be utilised for the purpose of cultivating 

 special species more for special objects. 



Recent phyto-chemical researches have led to important results in 

 this direction. Although a large number of chemical substances are 

 present in the eucalyptus oils, there exists a certain regularity in their 

 distribution among the individual species, and it is even possible from 

 the venation of the leaf to draw conclusions as to the principal 

 constituents of the oils 3 ). These groups are chiefly distinguished in 

 this manner. The oil of the first group whose leaves have a thick 

 midrib and marginal veins ending close to the edges of the leaf, 



x ) Comp. the present Report, under Analytical Notes. 



*) Journ. Soc. chem. Industry 26 (1907), 851. 



■') Comp. Report April 1902, 41; April 1906, 30. 



