— 52 — 



at the time of our experiments (Report April 1910, 154) because we regarded 

 it as a matter of course that the oil should be saponified for at least one 

 hour. But as Parry lays stress upon the fact that according to his ex- 

 perience geranyl acetate is completely saponified after half an hour we 

 may further add that this does not apply to isopulegyl acetate, into which 

 citronellal is converted by acetylation. This we have also ascertained by 

 experiment. With a freshly-prepared and carefully purified isopulegyl 

 acetate a constant ester value of 281,9 = 98,7 °/o ester was only obtained 

 after one hour's saponification. When heated for a longer period the 

 value was not increased, whereas after half an hour's saponification the 

 ester value was only 276,3 == 96,7 °/o ester. 



We certainly cannot acquit the English chemists of the charge of 

 not having paid sufficient attention to our recent publications, especially 

 to those relating to the acetylation of citronella oil, and when the Editor of 

 The Chemist and Druggist asserts that the acetylation-method of the English 

 chemists is also based upon experiment, we ask where the experiments 

 with mixtures of known geraniol- and citronellal-content which are said 

 to have been made by English chemists are published? For only by 

 such experiments is it possible to solve the question: not by acetylation- 

 tests with citronella oils. In the interests of the subject itself, and in 

 spite of Mr. Umney's indignation, we shall continue deeply to regret the 

 in our view arbitrary deviations on the part of the English chemists from 

 our acetylation-method. It is to be hoped that in further discussions on 

 the subject Mr. Umney will adopt a controversial style which is more 

 becoming and to the point, as we should otherwise feel compelled to 

 refrain from replying to his publications. In order to set his mind at 

 ease we declare once more that we are, and always have been, very 

 sympathetic indeed towards the geraniol-test as such, and that our sole 

 reason for advocating Schimmers simple and stricter test is because 

 we doubt the possibility of a general commercial application of the 

 geraniol-test for the present (comp. Report April 1911, 45). If, however, 

 Messrs. Umney and Parry should refuse to understand us, and should 

 persist in distorting our statements, we can only admit that we are 

 powerless to prevent it. 



Two slight misunderstandings should not be passed unnoticed. The 

 Editor of The Chemist and Druggist appears to believe that in the acety- 

 lation of citronella oil the objective is the evaluation of the esters in the 

 oil, whereas in point of fact the purpose of the acetylation is to determira 

 the geraniol- and citronellal-content. And against Kleber's view that 

 warming of the ready washed-out acetylated oil on the water-bath with 

 sodium bisulphate is superfluous, to say the least, Parry quotes the ace- 

 tylation-method described in the new edition of our book The Volatile Oils 

 (p. 594), in which it is stated, inter alia, that for the purpose of decom- 

 posing the excess of acetic anhydride the acetylation-mixture should be 



