364 



Process, in England, France, Germany, and America, as well as in the Australian 

 colonies. With this method available it was possible to introduce a stan- 

 dardised oil containing a guaranteed quantity of cineol, and to this end Messrs. 

 Faulding & Co. instructed their agent in England to call upon every retail 

 chemist in London, in order to explain the phosphoric acid method for testing 

 Eucalyptus oils. 



This method is convenient, and with ordinary care can be carried out 

 with fair success, particularly with Eucalyptus oils required to pass the official 

 standards, in which much cineol is now demanded. Although the method does 

 not indicate absolutely the actual amount of cineol present, yet, when undertaking 

 the work for the first edition, we found it most useful for arranging the oils of 

 the several members of the genus into groups, for the purpose of classification. 

 Unfortunately the method is not very satisfactory, for quantitative purposes, when 

 only a small amount of cineol is present, and it is necessary in such cases to 

 fractionate the oils and determine the amount of cineol in the most suitable 

 fraction. With the oils of many species the method cannot be employed, as the 

 cineol is too small in amount. 



The phosphoric acid method is official in the British Pharmacopoeia 

 and is there directed to be carried out in the following manner : " When 10 

 millilitres of the oil are mixed with 4 to 5 millilitres of syrup}' phosphoric acid 

 in a vessel surrounded by a freezing mixture, and then pressed strongly in a piece 

 of fine calico between folds of blotting paper, the pressed cake decomposed by 

 warm water in a graduated vessel yields an oily layer which on cooling to 15-5 C. 

 measures not less than 5-5 millilitres (presence of not less than 55 per cent, of 

 cineol)." 



A RAPfD PHOSPHORIC ACID METHOD, USING PETROLEUM ETHER. 



This method, which we now propose, works very well with most Eucalyptus 

 oils containing 20 per cent, of cineol or over, is quickly carried out, and thus 

 suitable for commercial analytical work. Eucalyptus oils which give a 

 compound that cannot be satisfactorily pressed by the British Pharmaco- 

 poeia method, may be readily determined in this way, and the decomposition 

 of the cineol-phosphate by long pressing particularly in hot countries is 

 prevented. 



The richest cineol oils give the best results when they are first diluted 

 with the addition of one-third the volume of freshly distilled pinene (turpentine) 

 or the non-cineol bearing portion of the more pronounced phellandrene 

 Eucalyptus oils. The method is recommended to be applied in the following 

 manner : 



If a preliminary test indicates from 60 to 80 per cent, of cineol, the oil 

 , is diluted as directed above ; if about 60 per cent, or below, it can be 



used directly. 10 c.c. of the oil to be determined are placed in a 

 suitable vessel which is stood in a bath of ice and salt, and 4 c.c. 

 of phosphoric acid are slowly added, a few drops at a time (3 c.c. 

 if below about 30 per cent.), incorporating these between each, 

 addition. 



The cineol-phosphate is then allowed to remain in the bath for 

 fully five minutes, in order that the combination may be complete. 

 A test tube containing 10 c.c. of petroleum ether, boiling below 

 50 C., is placed in the bath and when quite cold is added to the 

 cake of cineol phosphate and well incorporated with the mass, 

 using a flat-ended rod for the purpose. The mixture is at once 



