80 PROCEEDINGS OF SECTION' B. 



specific gravity at 16°C. was 0-8708 ; rotation, rt^,— 43-1° ; re- 

 fractive index, 1-4871, and it commenced to distil at about 175°C. 

 The principal constituent was found to be laevo-rotatory limonene, 

 the rotation thus being in the opposite direction to that of the 

 limonene in lemon oil; the amount of citral was 16 per cent, 

 which is considerably more than occurs in lemon oil. When the 

 oil was rectified by steam distillation the distilled product was but 

 slightly coloured, had a pleasant lemon oil odour, and in specific 

 gravity and other characters closely approached those of ordinary 

 lemon oil. always with the exception that the hmonene is laevo- 

 rotatory instead of dextro-rotatory. The specific gravity of the 

 steam-distilled product (77 per cent.) at -7!° =0-859 ; rotation 

 rt„ — 51-5^; refractive index at 22°C.=1-4771 ; citral, 16-5 per 

 cent, by the sodium bisulphite method. (The quantitative deter- 

 mination of the citral by this process acts very satisfactory, and 

 the readings were quite sharp.) The solubility in alcohol is very 

 good. 1 volume being soluble in 6 volumes 80 per cent, alcohol 

 by weight. 



Numerous friends kindly undertook to test the comparative 

 value of the essence made with the rectified oil of E. Staigeriana, 

 against the best lemon essence obtainable, the identity of the 

 Eucalyptus product being unknown to them at the time. For 

 flavouring puddings, jellies, and similar articles many reported in 

 favour of the Eucalyptus essence, while others failed to detect any 

 difference. As a flavouring agent for lemonade it is perhaps equal to 

 any essence obtainable, and this is also the case with lemon syrup. 

 Aerated lemonades made with it were found verv satisfactory. The 

 crude oil does not answer so satisfactorily, because the geranyl- 

 acetate present gives to the gas a slight aromatic odour, but when 

 the crude oil is rectified this odour cannot be detected. 

 The residue left on rectifying the oil should also be a valuable 

 product when properly prepared, owing to the geranyl-acetate and 

 geraniol it contains. 



The world's demand for lemon oil is very considerable, the 

 yearly export from Sicily alone being about 1,500,000 lb. at a 

 wholesale value of, say, about 3 lire per lb. The commercial possi- 

 bilities for the oil of Eucalyptus Staigeriana are thus most pro- 

 mising, and the cultivation of the plant is worthy of every con- 

 sideration. Another Mjnrtaceous plant. Leptospermum Liver sidgei, 

 also yields an oil rich in citral. ^ 



3. — Citronellal Oils. 



The only Australian Myrtaceous plant so far known which 

 yields an oil containing the aldehyde Citronellal in quantity is 

 Eticalyptus citriodora. This tree grows plentifully in the neigh- 

 bourhood of Gladstone, in Queensland, and is there worked for 

 its oil by distillation. It has been cultivated in several of the 

 other States, in India, and other places. The oil distilled from 



1 See Proc Roy. Soc. N.S.VV., 1905, p. 124. 



