— 44 — ( 



The phenylhydrazine method recommended by Kleber for the estimation 

 of citral and citronellal (comp. Report April 1912, 75) gave the following values 

 for citronellal after 1 hour's reaction: — 



Ceylon oil mixture .... 12,4 and 13,5 °/o 

 Java „ „ .... 47,3 °/o 



Ceylon „ II 7,5 and 9,3 °/o 



)ava „ 36,4°/o 



After about 4 weeks the experiments were repeated, the reacting of 

 the phenylhydrazine solution being extended to l 1 / 2 hours: — 



Ceylon oil mixture 14,8% 



Java „ „ 41,4% 



Ceylon „ I 8,4% 



n H 10,0% 



Java „ ....... .v 41,3% 



„ „ after % hours 33,2 °/o 



„ „ „ 1 hour 35,7%. 



From the above it would appear that in mixtures of a high percentage 

 the citronellal after 1 hour had not yet combined completely with the 

 phenylhydrazine, but on the other hand it is also possible that a partial 

 conversion into isopulegol takes place. This may be surmised inter alia 

 from the fact that the 4 weeks' old Java oil mixture, in spite of having 

 been left standing l 1 /* hours, did not give higher, but on the contrary 

 lower values with the phenylhydrazine solution than it did at first after 

 1 hour's standing. The experiments on this subject are being continued, 

 regard being had to the constants of the citronellal used and to the time 

 of action of the phenylhydrazine. 



Another method for estimating geraniol and citronellal in citronella 

 oils has been worked out lately by M. V. Boulez, who has kindly given 

 us some particulars of it in writing. He proceeds as follows: 25 or 50 g. 

 oil are shaken up in an Erlenmeyer flask with 100 or 200 g. of bisulphite 

 solution saturated with neutral sulphite, and left standing for 2 to 3 hours 

 until the aldehyde has been completely bound. 100 or 200 g. water are 

 then added and the mixture is heated several hours in a reflux condenser 

 with frequent stirring, until a complete separation has been effected between 

 the oil -layer and the aldehyde compound, which latter has dissolved in 

 the form of a sulphonic acid. The oil is now isolated in a separator, weighed 

 and acetylated. The loss of oil corresponds with the quantity of citronellal 

 which is present in the oil, and the geraniol-content is shown by acetylating 

 the undissolved oil. The bisulphite solution is said to be also serviceable 

 for the separation of other aldehydes. 



For a Ceylon oil with a so-called total geraniol content of 62,07 p. c. 

 Boulez found the following values: citronellal 18 p. c, geraniol 44,28 p. c. 



