49 





^5° 



«D 



Solubility 



Resorcinol 

 method 



Phosphoric acid 

 method 



I. 



2. 



0,9185 

 0,9186 



+ i°i3' 



+ o° 





7i°/ byvol. 

 82°/ „ 



5 1 and 62 °/ by vol. resp. 



3- 



4- 

 5- 

 6. 



7. 

 8. 



9- 



0,9142 

 0,9241 

 0,9158 

 0,9204 

 0,9221 

 0,914 



0,923 



+ o° 4 o' 



+ 2°2 5 ' 



- o°45' 

 -f o°io' 

 -f o°26' 

 + 4°55' 



+ 8° 5 o' 



soluble in 2 to 3 vol. and 

 more 70 percent, alcohol 



soluble in about 7 and more 



vol. 70 percent, alcohol 

 makes a cloudy solution 

 with 6 to 8 and more vol. 



8i°/ » 

 8o°/ „ 

 80,5 °/ „ 



85°/o .1 

 86°/ ,, 



77°/ „ 

 7o°/ * 



40 „ 5 l0 /o » 



10. 



0,928 



+ o° 4 i' 



70 per cent, alcohol 



soluble in 2 and more vol. 



70 per cent, alcohol 



94°/o .; 





11. 

 12. 



0,867 

 0,863 



—43° 40' 

 -6o°25' 



( soluble in 0,5 and more 

 <! vol. 90 per cent, alcohol 

 with opalescence 



29 °/ ,. 



2I°/o » 





In the case of oil No. 5 the eucalyptol was again separated off 

 from the resorcinol solution in order to test its purity, and the specific 

 gravity, rotation, and refractive index determined. It was inactive, 

 and had di 5 o 0,9275 and d d20° i>46o3I. If it is considered that 

 pure eucalyptol has a specific gravity of 0,928 to 0,930, the above 

 result shows that apart from eucalyptol only such small quantities of 

 other constituents of the oil pass over in solution, that they are of 

 no consequence for the practical value of the method. The degree 

 of purity of the eucalyptol separated off was also determined by 

 fixing the solidifying point, which (as we have convinced ourselves) 

 is also very useful for estimating the value of eucalyptol, as slight im- 

 purities already suffice to reduce the solidifying point considerably. Whilst 

 according to our observations pure eucalyptol congeals at about -}- 1 ° x ), 

 the above product separated from the resorcinol solution showed the 

 solidifying point — 4,6°, a result which may be characterised as quite satis- 

 factory if the unavoidable impurities dissolved mechanically are taken into 

 consideration. It should still be mentioned that the solidifying point 

 is determined in the usual manner 2 ). We cool the pure eucalyptol 

 below the freezing point to about — 5 ; in the case of less pure pre- 

 parations it is sometimes necessary to cool even below that temperature. 

 In this case also solidification must sometimes be started by inocul- 

 ation with a little solid eucalyptol. 



x ) In one case we determined the melting point of pure eucalyptol at about 

 -[- 1,5°; the previous statement that pure eucalyptol melts at — i°, is therefore 

 incorrect and should be amended. 



2 ) Gildemeister and Hoffmann, The Volatile Oils, p. 176. 



4 



