I - 43 - 



of strong formic acid), gives insufficient results, and it will therefore 

 probably be necessary to abandon this method. According to it, the 

 mixtures and oils referred to above yielded the following results: — 



Ceylon oil mixture 11 p. c. citronellal 



Java oil mixture 15,5 „ „ 



Ceylon oil I (so-called total geraniol 61,7) 20,2 „ „ 



„ II ( „ „ » 52,6) 16,9 „ 



Java oil 24,1 „ „ 



Citronellal (80 p. c.) 28,0 „ 



Geraniol 11,15 „ Ci Hi 8 O. 



The value found for geraniol explains also why, when citronellol is 

 estimated by this method (comp. Gildemeister, Die dtherischen die, 2 nd edition 

 Vol. I, 600), the citronellol-values are somewhat too high. 



On the other hand, the method recommended by us 1 ) for the separate 

 estimation of geraniol with phthalic anhydride proved to be very serviceable 

 indeed; only, the assumption that the proportion of citronellal which is 

 present in the oil can be ascertained by the simple subtraction of the 

 geraniol-content from the content of acetylisable constituents is incorrect, 

 for the recognised methods of estimating citronellal invariably give much 

 lower values than those of the difference in question. In concluding we 

 will again refer to this matter. 



The method is carried out as follows: — 



About 2 g. phthalic anhydride and 2 g. of the oil under examination 

 are heated on the water-bath for 2 hours with 2 cc. benzene in an acetylation 

 flask. The mixture is then left to cool and is shaken for 10 minutes with 

 60 cc. aqueous seminormal potash-solution. During this manipulation the 

 flask is stoppered with a ground glass stopper. At the end of this time 

 all the anhydride is converted into neutral potassium phthalate and the 

 acid geraniol ester into its potash-salt. The excess of alkali is now 

 titrated back with seminormal sulphuric acid. By deducting from the 

 quantity of alkali which corresponds to the phthalic acid used in the 

 experiment, the quantity consumed in the reaction, the equivalent in alkali 

 of the geraniol which has been combined with the phthalic acid is obtained, 

 and from this result the percentage of geraniol is calculated. 



The experiments with phthalic anhydride gave: — 



for the Ceylon oil mixture . 47,9% geraniol 



» » Java „ „ 41,1% 



„ Ceylon oil I (so-called total geraniol 61,7%) 34,4 % . 



n n II ( „ „ „ 52,6%) 29,6% 



n Java „ ( „ „ „ 83,8 %) 26,6 % 



Java oil after 4 weeks 27,6% 



*) Report October 1899, 19; April 1900, 14. 



