# - 45 - 



= 62,28 p. c; for a Java oil with a so-called total geraniol content of 

 84,50 p. c. he found 63 p. c. citronellal and 35,56 p. c. geraniol = 98,56 p. c. 

 It is worthy of note that the sum total of citronellal and geraniol found 

 in the Java oil considerably exceeds the total geraniol content. 



When the method was submitted to a control-test it was discovered 

 that, with an increasing citronellal-content, the solubility of the oil which 

 does not react with bisulphite (especially of the geraniol), becomes so 

 great as to make the values given by the method for oils of high 

 citronellal-content much too high, the reason being that the oil which has 

 been dissolved in the liquor is taken into the calculation as citronellal. 

 We found, for instance, that in a mixture of 20 g. citronellal and 5 g. 

 geraniol, after treatment with 100 g. bisulphite solution and 100 g. water 

 and warming, the entire geraniol had dissolved clearly and that in 

 cooling only a very small proportion of oil was separated out, and when 

 we extracted the cooled-down solution with ether, only about 80 p. c. of 

 the geraniol used was recoverable. 



It was further shown that one hour's heating on the water-bath is 

 quite sufficient to bring about the separation of oil and water. 



Experiments by Boulez' method have afforded us the following values 

 with 1 hour's heating: — 



the Ceylon oil mixture 17 p. c. citronellal and 42,5 p. c. geraniol = 59,5 p. c. 



„ Java oil mixture . 55 „ „ „ 41,9 „ „ =96,9 „ 



Ceylon oil I 7 „ „ ,,51,0 „ „ = 58,0 „ 



n i) 11 ,, v u 44,0 „ „ = OU,0 „ 



Java oil 54 „ „ „ 24,8 „ „ = 78,8 „ . 



With the Java oil mixture a citronellal-content of 60 p. c. and more 

 was repeatedly ascertained. As the unchanged oil can only be very 

 imperfectly recovered from the liquor, even with ether, this method, as 

 already stated, is unsuitable for oils with a high citronellal-content, that 

 is to say for Java citronella oils, but on the other hand it may be found 

 very serviceable for the examination of Ceylon citronella oil. 



From what has been said above the conclusion may be drawn that 

 the separate determination of both geraniol and citronellal in citronella 

 fc oil is possible. For the former the phthalic anhydride method is the only 

 one which is of any value, as in al the other methods, in addition to 

 geraniol, the other alcohols which are present in the oil are also estimated 

 at the same time. For determining the citronellal-content the oximation- 

 method is suitable, and it is probable that the phenylhydrazine method 

 recommended by Kleber may also be applicable for this purpose, but with 

 regard to the latter further experiments are necessary. In the case of 

 Ceylon citronella oils the citronellal-content may be ascertained by the 

 method of Boulez. 



