The nitrosite from the laevo-rotatory phellandrene is strongly dextro- 

 rotatory, while, that from dextro-phellandrene is laevo-rotatory, but both are 

 similar in appearance and melt at the same temperature. They have been 

 shown by Wallach and Beschke (loc. tit.) to form two isomeric nitrosites, which 

 may be separated by crystallising from acetone and alcohol ; the laevo-a-phcl- 

 landrene-a-nitrosite melting at 112-113 C, and the laevo-a-phellandrene- 

 /3-nitrosite at 105 C. ; the dextro forms melted also at the same temperature. 



Tcrpinenc in Eucalyptus Oils. 



The occurrence of this terpene in the oils of certain Eucalypts was first announced 

 by one of us, in a paper read before the Royal Society of New South Wales in 

 December, 191S. It had been isolated from the oil of E. megacarpa, a West 

 Australian species, forwarded to the Technological Museum for investigation by 

 Mr. C. E. Lane-Poole, the Conservator of Forests for that State. 



The oil of this Eucalypt consists principally of terpenes, and in addition 

 to the terpinene, pinene and limonene were both detected, and their character- 

 istic chemical combinations prepared. 



Limonene rarely occurs in Eucalyptus oils, and it may be that terpinene 

 will be found more frequently associated with that terpene in the oils of species 

 growing in the northern and north-western portion of Australia, and at present 

 uninvestigated. The formation of terpinene from terpineol through the 

 terpene terpinolene is thus of special interest, because dipentene can also be formed 

 from terpineol, and it is now known that this alcohol is a common constituent 

 in the oils of many Eucalyptus species. 



The pinene and limonene in the oil of E. megacarpa were both laevo- 

 rotatory, and it is possible that dipentene was present also. The cineol content 

 was 30 per cent., and from the aggregate of results it appears that about 10 per 

 cent, of terpinene was present also. 



Terpinene can be formed artifically by the action of alcoholic sulphuric 

 acid on many of the terpenes and terpene derivatives, as well as from terpineol, 

 geraniol, dihydrocarveol, and cineol. This formation is thus interesting in this 

 connection, as besides cineol, pinene, and limonene, geraniol was also present as 

 an ester in the oil of E. megacarpa. 



Terpinene was first recognised as a sepaiate terpene by Wallach [Ann. 

 (230) 254], but has so far been detected in only a very few essential oils, such 

 as those of Marjoram, Dill, and Coriander. It has been suggested that in these 

 cases its presence may have been brought about by the influence of heat during 

 distillation, but this opinion cannot now be supported in so. far as it relates 

 to Eucalyptus oils. 



Terpinene has not, so far, been regenerated from its solid derivative in a 

 pure form, so that its physical properties cannot be definitely stated, but from 

 the results of various observations the following may be given : — Boiling point, 

 171-181 C. ; specific gravity, 0-842 at 22° C. to 0-848° at 18°; refractive index, 

 1-4719 to 1-4789. 



