EUCALYPTUS. 255 



per cent, being geranioL* Oil of E. maculata, var. 

 citriodora possesses the characteristic property of being soluble in 

 4 to 5 parts of 70 per cent, alcohol.f 



Citronellon is an aldehyde possessing some analogy to Citral 

 (which see) but distilling at a lower temperature. It is the chief 

 constituent of oil of Andropogon xY«?y?z/.s ( citronella) (see 1st series), 

 and was isolated from that oil by Dodge,:|: who ascribed to it the 

 formula C^q H^g O. By treatment with sodium amalgam, it can 

 be converted into Citronellyl alcohol, C\o H^^ 0. By oxidation it 

 yields citrondlic acid C-^^ H^g 0^. 



In the above-mentioned paper by Dodge, he says, in reference to 

 the separation of this aldehyde from oil of citronella : — "When the 

 oil is shaken with a saturated solution of sodium bisulphite, after 

 ten minutes the liquid solidifies with considerable evolution of 

 heat. On standing, the mass becomes yellow on the surface, owing 

 to oxidation of other constituents of the oil. The bisulphite 

 compound is readily obtained pure l)y thinning with ether or 

 chloroform, filtering and washing with the same solvents, in which 

 the precipitate is practically insoluble. Alcohol does not work so 

 well. The bisulphite precipitate is readily decomposed by acids, 

 alkalies, sodium carbonate, or hot water, which regenerate the 

 iildehyde." As regards the isolation of the aldehyde, he says : — 

 "The washed bisulphite compound, freed from ether by short 

 exposure to the air, was gradually added to a warm solution of 

 sodic carbonate and kept warm until the white precipitate had 

 disappeared. The supernatant oil was then separated and dried. 

 On distillation, the greater part boiled from 200^-210^ C, leavinci: 

 a thick residue which did not react very readily with phenyl- 

 hydrazine. This indicated an alteration of the aldehyde due to the 

 heat of distillation. To avoid this difficulty, the oil liberated from 

 the bisulphite compound was immediately distilled in a current of 

 steam ; a plan which succeeded admirably, a pure w^hite oil passing 

 over, and a small quantity of dark-coloured oil remaining in the 

 flask." Operating upon a larger quantity he details the process as 

 follows : — Two litres of citronella were distilled ; the first portion 

 of the distillate, 1100 c. c, was divided into four parts of about 



* Bericht, Oct., 1893. 



t Ibid. 



X Am. Chem. Journ., xi., pp. 456 and 469, 



