- 4 3 - 



cassia flask with the addition of caustic soda liquor, in order to determine 

 in this manner the cineol volumetrically, gave no satisfactory results. 

 On the other hand, the end in view was obtained by the observation 

 that the cineol - resorcinol is soluble in a concentrated solution of 

 resorcinol, and that its crystalline separation can be prevented, if from 

 the first an excess of resorcinol solution is employed. In this manner 

 it is possible to abstract the total cineol from the oil in question, 

 and to retain it in solution in the form of the resorcinol addition - 

 product, but for this purpose a highly - concentrated (5O°/ ) resorcinol 

 solution is required, whilst with less strongly concentrated solutions 

 (even 40 to 45%) no quantitative separation takes place. The 

 quantity of the oil not consisting of cineol is ascertained by volume 

 and thus the cineol - content determined. 



The determination is carried out as follows: 10 cc. of the oil con- 

 taining cineol are mixed in a cassia flask of 100 cc. capacity with so 

 much 50% resorcinol solution that the flask is filled for about 4 /s- 

 The mixture is shaken thoroughly for 5 minutes, and the oil-portions 

 which have not entered into reaction are brought into the neck of 

 the flask by adding resorcinol solution, and their volume determined. 

 By subtracting this volume from 10 the cineol - content of the oil is 

 obtained, which is then expressed in per cent, by volume by multipli- 

 cation with 10. 



Oils very rich in cineol are suitably diluted beforehand with an 

 equal volume of turpentine oil, as otherwise the cineol-resorcinol might 

 crystallise out and cause the whole liquid to solidify, preventing so the 

 determination. In this case the result must of course be multiplied 

 with 2 . 



The volume of the oil remaining behind should not be read off 

 too soon; the resorcinol solution should first of all be completely or 

 almost completely cleared, and by occasionally turning and tapping 

 the cassia flask, care should be taken that any oil-drops adhering to 

 the walls of the vessel rise to the surface. 



In order to test the reliability of the method we have prepared 

 various mixtures and ascertained their cineol - content in the manner 

 just described. We reproduce the results in the following table: — 



1 . 25 vol. °/ cineol +75 vol. °/ turpentine oil ; found 2 7 °/ 



2. 33 » ». +67 » » » 34 » 

 3- 5o » „ +50 „ „ „ 50 » 



4. 80 „ „ -f 2 ° » » " 8o >5 » 



5. 30 „ ,, -f~ 20 ,, „ -f- 50 vol.°/ phellandrene; found 3O°/ 



6. 50 „ „ + 2 ° » » + 30 » » » 5° » 



We have also assayed a number of eucalyptus oils for their cineol- 

 content, and in some cases also quoted the results obtained by the 

 phosphoric acid method, which clearly shows the unreliability of 

 the latter. 



