— 162 — 



for every expert knows that the observance of definite conditions is in- 

 dispensable in most chemical determinations. In the case of the four oils 

 mentioned above the practice of determining the solidifying -point has 

 proved its efficacy so thoroughly that one can only express the wish that 

 as much might be said of all other tests for the valuation of essential 

 oils. Mr. Umney's suggestion that this test should be abandoned in favour 

 of the much less accurate method of determining the melting-points of 

 these oils should therefore be decidedly rejected. 



In the case of otto of rose it is not, strictly speaking, the solidifying 

 point that is determined, but merely the temperature at which paraffin 

 crystals begin to separate out when the oil is cooled down slowly. In 

 our opinion there is here also no reason for changing this mode of de- 

 termination, which is quite useful in practice, in favour of the one desired 

 by Mr. Umney. 



A reaction for the higher alcohols (i. e. amyl alcohols, 8jc.) recommen- 

 ded by Komarowsky *) is based upon the fact that these alcohols, in ethyl- 

 alcoholic solution with concentrated sulphuric acid and salicylic aldehyde, 

 assume an intense red colour. H. Kreis 2 ) has recently shown, however, 

 that this reddening is also caused by other bodies. Kreis was testing 

 essential oils of lemon and orange for the presence of the higher alcohols 

 and in the course of this work obtained an extraordinarily strong reaction, 

 which, as afterwards became evident, was caused by the terpene-bodies 

 which were present. The examination of a series of terpenes and essen- 

 tial oils for their behaviour towards salicylic aldehyde and sulphuric acid 

 gave the following results: intense reactions were obtained with pinene, 

 limonene, phellandrene, terpineol, menthol, cineol, citral, citronellal, car- 

 vone, thujone, oils of anise and staranise, oil of balm, oil of sage, and 

 oil of tansy. Fenchone, menthone, and camphor gave no reaction, but 

 only a yellow tinge, as with pure ethyl alcohol. Pulegone gave a faint 

 reddish-brown, but no characteristic coloration. With concentrated sulphuric 

 acid, the bodies which had given a red colour only yielded pale brownish- 

 yellow solutions, while in the case of fenchone, menthone and camphor 

 the sulphuric acid remained almost colourless. 



For the quantitative determination of linalool and other similar alcohols 

 which readily give off water, Jeancard and Satie 3 ) recommend that the oil 

 in question should be diluted before acetylation with a neutral agent, 

 a process which has already been proposed some years >argo by Boulez 4 ) 

 and was discussed in these Reports at length at the time 5 ). Jeancard and 



i) Chem. Ztg 28 (1903), 807, 1086. 



2 ) Ibidem 34 (1910), 470; also comp. v. Fellenberg, Ibidem 791. 



3 ) Americ. Druggist 56 (1910), 42; quoted from Journ. Soc. chem. Industry 29 (1910), 296. 

 *) Corps gras industries 33 (1907), 178; Bull. Soc. chim. IV. 1 (1907), 117. 



5 ) Report April 1907, 119. 



