258 ODOROGRAPHIA. 



boiling under 200° C, which amounted to about 4 per cent., 

 showed none of the characteristic reactions of Cineol (Eucalyptol), 

 and it must therefore be assumed that this body is not present in 

 the oil of E'ucaly2^tus maculata var. citriodora. The well rectified 

 oil is colourless, and has a pleasant melissa-like odour. 



It is considered that the oils of E. Bcdleyana, E. microcorys and 

 E. maculata var. citriodora are very similar in composition. 

 Citronellon has been found in E. dealbata. 



E. microcorys, Mueller, called the "Sallow wood" of 

 ISTorthern New South Wales, is found in the Coast districts to 

 Cleveland Bay. The yield from the fresh leaves is nearly 2 per 

 cent., sp. gr. 0-896, boils at 160° to 200° (Staiger). 



E. Staigeriana. The " Lemon-scented Iron Bark " of the 

 Palmer Elver, Queensland. The leaves are obtainable from 

 Maytown ; they possess an odour very like that of scented verbena. 

 Staiger says the odour of the oil is so exactly like that of oil of 

 verbena that it would be difficult to distinguish it by its odour 

 alone, although it differs in its lower specific gravity, which is 0-871 

 or when freed from moisture 0-880*, that of verbena being 0-890.-|- 

 The oil, when fresh, contains from O'l per cent, to 0-3 per cent, of 

 water, which can easily be removed by calcic chloride. An 

 important constituent of oil of E. Staigeriana is Cit7'al C^q H^g 0, 

 an aldehyde that is of very frequent and extensive occurrence in 

 essential oils, and especially occasions the characteristic aroma of 

 lemon oils and oils having a lemon-like and verbena odour, such 

 as those of Andropogon Citratus (Lemon-grass), Bachhausia 

 Citriodora, and the fruit of Tetranthcra citrata. The elementary 

 arrangement of Citral is doubtful, but the fact that geraniol 

 is converted into citral by oxidation, and citral itself into geranic 

 acid, suggests that it is also a chain compound with the corres- 

 ponding formula : — 



'\ 



\H-CH,-CH = CH-a(CH3) = CH-CH0 

 CH3 



* Pliarm. Journ. [8], xvii., p. 142. 

 + Ibid [3], X , p. 212 



