portion which came ovei between [70 [go 1 beinj u ed for the absorption, 

 and the result calculated for the original oil Iso in this connection C. F. 



Bennett, "Perfumery and Essential Oil Record," Oct., i«,u. 



With the heavj cineol Eucalyptus oils oi thi I 1 class, in which 



only a \'i\ small portion distils below 1 this modified method may 



succeed in concentrating the cineol, bul with thi ineol oils in which a 



considerable fraction 1- obtained boiling below 170 < a good deal ol cineol 

 comes over in thai portion, and it does nol seem possible, by direcl distillation 

 nt oils ol this class, to prevent much cineol distilling over with the pinene 

 in this way. 



With a Large number ol Eucalyptus oils in which cineol 1- onlj present in 

 small amount and other constituents soluble in resorcinol not a1 all pronounced, 

 the process acts very well, and cineol as low as 5 per cent, ran be determined in 

 this way. Such oils are those consisting largely ol pinene, as E. dextropinea, 

 /•.'. Itzvopinea, &c, and many of the phellandrene bearing oils, such as E. oreades, 

 ! Delegatensis, E. stellulata, &c. 



The method was also found useful for comparative purposes, as, Eot 

 instance, in the investigation of the nils oi E. Smithii from various tonus oi 

 growth Proc. Row Soc, N.S.W., Aug., 1915 . Those results are also published 

 in this work. The oil of this species contains a very small amount oi substances 

 other than cineol absorbable by resorcinol, and this is also the case with that of 

 E. polybractea and a lew others of the richer cineol class. 



The resorcinol method may be considered a useful one for determining 

 the cineol in a number of Eucalyptus oils, and may be satisfactorily employed lor 

 that purpose, but is more particularly applicable with those for which the 

 phosphoric acid method is useless. Like all other known methods it is not of 

 universal application, owing to the great diversity of constituents in Eucalyptus 

 oils, and it thus becomes necessary to discriminate when choosing the method 

 to be employed. The resorcinol process is also useful in assisting the investigation 

 of undetermined Eucalyptus oils. 



Unfortunately many constituents which occur in varying amounts in 

 Eucalyptus oils are absorbed by 50 per cent, resorcinol, equally with cineol, and 

 this is the case with the alcohols, as geraniol, terpineol, eudesmol, amyl, butyl, 

 &c. ; the aldehydes as aromadendral, citral, citronellal, butaldehyde, &c. ; the 

 lower esters as amyl-acetate, butyl-butyrate, &c. ; piperitone and other bodies 

 containing oxygen. 



It is thus evident that the resorcinol method cannot be expected to give 

 accurate results with all Eucalyptus oils, particularly those in which the 

 constituents enumerated above occur in quantity, and it is difficult, if not 

 impossible, with the oils of many Eucalyptus species to prepare a traction in 

 which the whole of the cineol is concentrated, and at the same time for it to be 

 comparatively free from other absorbable constituents. It these are known, 

 however, they can be separately determined, and allowed for, and in this way 

 the cineol results might be made fairly accurate. 



Illustrations oi this procedure are given under /•.'. dives, E. piperita, and 

 other species in which the amount of piperitone in the [taction boiling below 

 Ego C. was separately determined and allowed for. 



As illustrating the difficulties in this connection the following analyses are 

 given, and the four oils investigated are quite representative oi the cineol Eucalyptus 

 oils at present found on the market. The data have been obtained from the 

 rectified oils distilling below [go c C, in order that the results with the rapid 

 phosphoric acid and resorcinol methods might be compared, and the amount oi 

 absorbable constituents, other than cineol, indicated 



50068— -■ \ 



