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We wish to be allowed to offer a few comments upon the inter- 

 esting researches of the esteemed author: — 



Chemically, cananga oil and ylang ylang oil differ in that cananga 

 oil contains fewer esters, fewer alcohols, and more sesquiterpene. 

 According to de Jong, this is due chiefly to the influence of climatic 

 conditions upon the cananga trees. In Java also there are trees of 

 which the flowers have a somewhat different and more agreeable odour, 

 and de Jong was able to obtain flowers from these trees, which are 

 known as Canangadedes. From these flowers he obtained an oil of a 

 somewhat higher ester content, but the ester content of ylang ylang oil 

 could not even approximately be reached, because he did not change 

 the distilling process but carried out this distillation also by means of 

 water. 



It is possible that climatic conditions have something to do with 

 the matter, but in all probability the mode of manufacture is of greater 

 importance as regards the difference in the two oils. In any case it 

 may be taken for granted that the distillation process followed in Java 

 must result in an oil poor in esters and rich in sesquiterpenes. This 

 is another example of the great differences which may exist in the 

 character of essential oils according to the method of distillation by 

 which they were obtained. 



In the first place, flowers used for distilling purposes should never 

 be pounded. There are not many flowers in which such a process 

 can be applied without injuring the quality of the essential oil. In 

 the case of fleshy, juicy flowers, the pounding process may easily 

 give to the oil an additional herbaceous odour. It is true that by 

 pounding the flowers distillation is facilitated and that the yield of 

 oil is increased, but in this particular case it is at the expense of 

 the perfume of the oil. The destruction of the flowers liberates the 

 essential oil from the cellular tissues, and thereby enables those con- 

 stituents of the oil which are insoluble in water and have a high 

 b. p. — among them especially sesquiterpene — to volatilise more 

 easily, while volatilisation of such constituents from entire flowers is 

 difficult and only possible to a very slight extent. This explains the 

 higher proportion of sesquiterpenes with a high b. p. in cananga oil. 



Distillation by water in the case of this oil is also a mistake, 

 because it has a decomposing action upon the esters and because it 

 impedes the evaporation of those parts of the oil which are the most 

 readily soluble in water, especially of benzyl alcohol and of isoeugenol 



The decomposition of the esters is further increased by the long 

 duration of the distilling process, for it is impossible to distil rapidly 

 owing to the totally insufficient means of cooling. 



Again, the distillation water should not be returned to the flowers, 

 as it contains acetic acid from the destroyed esters, and, according 



