3 88 



and the purified crystalline sulphite compound decomposed by sodium carbonate. 

 At that time of the year phellandrene was not detected, and cuminal was 



almost absent. 



The constants for aromadendral from E. hemiphloia at that time were : — 

 Specific gravity = 0-9477; rotation a B - 1^6-6°, and refractive index at 20° = 

 1-5086. The oxime melted at 84 85° C, the naphthocinchoninic acid at 247 O., 

 and the acid at no° C. In the light of the present investigation it is apparent 

 that a little cummal was present also, and this is indicated by the figures given 

 above. The analysis, however, gave insults closely agreeing with those required 

 for a C IO H I4 aldehyde, and the acid was also in agreement with the C 10 H J4 2 

 molecule. 



As the total amount of aldehydes extracted at that time only amounted 

 to 3-3 per cent., it is evident that cryptal was not included. 



The C IO H M aldehyde occurring in Eucalyptus oils was originally named 

 aromadendral (Proc. Roy. Soc, N.S.W., Dec. 1900), derived from the name 

 aromadendron given to the genus by Dr. \Y. Anderson, the surgeon of Captain 

 Cook's second and third expeditions. 



The constants for aromadendral from the oil of E. rostvata prepared from 

 the crystallised sulphite compound were : — Specific gravity at 20° C. = 0-9534 ; 

 optical rotation <7 D — 70-72; refractive index at 20 = 1-5066. The oxime melted 

 at 84-85 ° C. It is thus apparent that a little cuminal was present here also. When 

 aromadendral shall have been separated in a pure condition, it seems probable 

 that the refractive index will be about 1-5 and the specific gravitv about 0-95 

 at 20 C. 



Citral. 



This constituent, found in some Eucalyptus oils, is one of the olefine terpene 

 aldehvdes, and because of its close relationship to geraniol is sometimes named 

 geranial ; it can be obtained artificially from geraniol by careful oxidation with 

 the ordinarv chromic acid mixture. Citral is evidentlv formed in the oils of 

 some species of Eucalyptus by natural oxidation of the geraniol, and this is 

 very well shown with those of E. Australiana, E. phellandra, &c. 



In the Nerrigundah, or South Eastern part of New South Wales, the oil 

 of E. Australiana contains geraniol in the free condition, and also as an ester, 

 but only to a small extent. In the Burraga district of the same State, about 

 200 miles from the first locality, some of the geraniol, common to this species, 

 has oxidised naturally to citral, and this feature is so characteristic that the 

 secondarv lemon odour of the oil of E. Australiana from the Burraga district is 

 usually a sufficient test by which to indicate the locality where the oil had been 

 distilled. 



Geraniol is such a common constituent in Eucalvptus oils that it might 

 perhaps be expected that citral would often occur, but this is not so, and only 

 very occasionally has it been found in the oils of the Eucalypts. The species, the 

 oil of which contains citral in greatest abundance, is E. Staigeriana, a 

 Queensland tree. (See under that species in this work.) 



Citral has a distinct lemon odour, so that its presence in a Eucalyptus oil 

 can usually be detected, and as it boils at a high temperature '228-230° C. at 

 atmosphere pressure) it is possible to largely concentrate it in the higher boiling 

 portions. Citral, similarly with most aldehydes, can be isolated by agitating the 



