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 Pharmacopoeia 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 500 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 transferred to a small Buchner funnel, 5 cm. in diameter, upon which is placed a closely fitting filter paper. The non-combined portion is then rapidly sucked away by the aid of the filter pump. The thus dried cake is then transferred to a piece of fine calico, the calico folded over and the cake spread with a spatula to cover an area of about 6 cm. by 8 cm., finally folded into a pad, which is placed between several layers of absorbent paper and the whole strongly pressed for three minutes. The cake is then broken up with a spatula on a glazed tile or on glass, transferred to a measuring flask with graduated neck, decomposed with warm water, the cineol lifted into the neck of the flask, cooled, and when the separation is complete the volume measured. If the original oil were diluted a correction is, of course, necessary. We have obtained very concordant results with the same sample of Eucalypus oil and now use the method constantly. In order to test the range of accuracy with this method, using pure cineol, and mixtures of cineol and the phellandrene fraction of Eucalyptus radiata and E. dives, the following tabulated results were obtained. The cineol content in the mixtures employed had the following range, 80, 66.6, 60, 40, 33.3, and 20 per cent. The more satisfactory results were obtained when the mixtures richest in cineol were diluted. To secure good results the acid should be added slowly, the mixture made very cold, and the petroleum ether rendered quite cold before adding to the cake.

* The cineol remaining from these determinations had specific gravity at 150 = 0.929; rotation aD - 0.2°; refractive index at 200 = 1.4607.

† The cineol from these determinations had specific gravity at 15° = 0.929; rotation nil; refractive index at 200 = 1.4589.

A more perfect separation by the rapid method is thus shown,