Commercial and scientific notes on essential oils. 43 



lavender immediately after collection, c) fresh cultivated lavender immediately after 

 collection. The mean of a large number of analyses of the oils obtained gave the 

 following results: — 



-Ot. 



Density 

 at 15°. 



Solubility 

 in 70 per cent, alcohol. 



«D. 



Esters 

 as linalyl acetate. 



a 



0.894 



5 vols, with difficulty 



5° 45' 



56.4 per cent. 



b 



0.889 



3 „ 



7° 20' 



50.8 „ „ 



c 



0.887 



3 „ 



7° 50' 



52.1 „ „ 



The three oils were submitted to distillation with a current of steam under reduced 

 pressure, giving the subjoined results: — 



(a) essential oil 79, resinous residue 21 per cent. 



(c) „ „ 96, „ „ 4 „ 



The resinous residues hat little odour, but gave the following percentages of 

 ester: -(a) 65.4, (b) 62.3, (c) 62.6. 



The authors conclude from these results that the figures representing the total 

 ester content are misleading and that it would be necessary to deduct the ester content 

 of the inodorous resinous residues, when the real percentages of ester would be: — 

 (a) 42.7, (b) 45.8, (c) 49.6 1 ). 



It further results from the experiments that lavender which has been piled up to 

 await distillation always gives a false titration, as resins with high ester content are 

 formed by oxidation at the expense of the essential oil. According to Lautier Fils, 

 the essential oils drawn from such flowers possess neither body nor fineness, although 

 they are pure and have high titration figures for esters. They say that the value of 

 lavender oil depends upon its "body" and upon its "bouquet", which had nothing to 

 do with the percentage of esters, and that oils from the Alps with only 26 per cent, 

 of esters were often far more valuable on account of their "bouquet", than other 

 products with 45 per cent. 2 ). 



The authors come to the following conclusions, which do not contain anything 

 new: — Bouquet and body are two distinct factors. The body is approximately in- 

 dicated by the ester titration. Absence of artificial esters must be ensured, in order 

 that the titration figures should be genuinely indicative of value and purity. — There 

 is no clear answer, however, to the question put in the beginning. 



We would say that these investigations do not alter the fact that, generally speak- 

 ing, the value of lavender oils depends upon the percentage of. esters. The more 

 careful and appropriate the distillation of the lavender oil, the higher the percentage 

 of esters and the less damage is done to the bouquet. 



The paper from the Roure-Bertrand Fils Laboratories 3 ) contains extensive, though not 

 altogether new details regarding the distillation, composition, analysis and adulteration 

 of lavender oils. The best lavender oils are obtained, if due attention is given to the 

 following points: — 1) When distilling by direct heat, the flowers ought not to be 

 soaked in water beforehand. The still must not be filled with too much water, as an 

 excess of water diminishes the yield of oil and impairs its quality. 2) The distillation 



*) The authors seem to have overlooked that a second steam distillation must needs cause a further 

 saponification of esters and an alteration of the oil. It is not stated whether the distillation was carried out 

 under ordinary pressure or in vacuo. — 2 ) This has been pointed out already by Birckenstock. Comp. Gilde- 

 meister and Hoffmann, The Volatile Oils, 2 nd edition, vol. Ill, p. 428. — 3 ) Perform Record 12 (1921), 344. 



