A characteristic test for this sesquiterpene is the very fine colour 

 reactions it gives with bromine, and with the halogen acids. 



The bromine test is best carried out in the following manner : 



One or two drops of the sesquiterpene are dissolved in 2 or 3 c.c. of 

 glacial acetic acid, and the vapour of bromine allowed to pass down the tube 

 until it reaches the liquid ; a crimson colour is immediately formed, which rapidly 

 passes downward and throughout the whole of the liquid ; if agitated the whole 

 becomes crimson, soon changing to violet, and in a short time to a deep indigo- 

 blue colour, which, under favourable conditions, remains for some days. This 

 test is exceedingly delicate, but the bromine should not be added in excess. 

 The reaction appears to be due to the formation of hydrobromic acid immediately 

 the bromine meets the sesquiterpene, and identical colour reactions were 

 obtained when one or two drops of hydrobromic acid were added directly to the 

 acetic acid solution, not mixing the two liquids. On heating the blue liquids, 

 they became reddish-brown, but usually recovered the indigo-blue colour 

 on standing. 



When one or two drops of concentrated hydrochloric acid were added to 

 the acetic acid solution, prepared as for the previous tests, a crimson colour was 

 obtained at once ; this soon changed to violet, and, on standing some hours, to 

 an indigo-blue colour. Here again the colours were more brilliant if the liquids 

 were not mixed by agitation. 



When one or two drops of concentrated sulphuric acid were passed to the 

 bottom of an acetic acid solution prepared as above, a bright crimson colour was 

 at once formed at the junction of the liquids ; on mixing these, the crimson colour 

 first formed, changed to a purplish-brown rather than to the violet colour formed 

 with the halogen acids. On boiling, the solution first became violet, then deep 

 crimson. 



When a few drops of phosphoric acid (specific gravity 1-75) were added to 

 the acetic acid solution prepared as above, a rose-madder colour formed at 

 the junction of the liquids ; on mixing the acids after the colour had formed, the 

 liquid changed in a few minutes to crimson, and then slowly to violet. It is 

 thus evident that the pink colour given to Eucalyptus oils when treated with 

 phosphoric acid is due to the influence of the sesquiterpene. 



In order to prepare the sesquiterpene in as pure a condition as possible, 

 300 c.c. of the crude oil of E. nova-anglica were directly distilled under reduced 

 pressure, and the fractionation repeated until finally 50 c.c. were obtained boiling 

 at 124-125 C., at 10 millimetres pressure. 



It was not easy to entirely separate the laevo-rotatory sesquiterpene 

 alcohol from the dextro-rotatory sesquiterpene, and it was necessary to finally 

 distil over sodium before an oil with a constant rotation was obtained. The 

 sesquiterpene, when thus prepared, had a slight yellowish tinge, was quite 

 mobile, had a not unpleasant odour, nor was it readily soluble in alcohol. 



The constants for the sesquiterpene were determined as follows : Boiling 

 point, under ordinary atmospheric pressure 260-265 C., and under 10 milli- 

 metre's pressure 124-125 C. ; specific gravity at 15 C. = = 0-9222 ; rotation a D 

 + 4-7; and refractive index at 20 = 1-4964. 



Molecular refraction calculated for C I5 H 24 with one double bond = 64-45 ', 

 found 64-89. It thus appears that aromadendrene contains one double linkage 

 in the molecule. 



An analysis gave the following results : 



0-1366 gram, gave 0-4388 gram. CO 2 and 0-1502 H a O. 

 Carbon 87-6 per cent, and hydrogen, 12-2 per cent. 

 C,,H 24 requires 88-3 per cent. C., and 11-77 per cent. H, 



