SCIENTIFIC NOTES ON ESSENTIAL OILS. : 19 
Even for artificial oils, density and ester values are abnormal to such an extent 
that from them alone the peculiar composition of the oils may be judged. Based on 
the ester v., the ester, calculated for linalyl acetate, would be 141 p.c. and 202 p.c. 
respectively, figures which are quite impossible and from which it can be deduced at 
once that considerable quantities of esters are present which should not be found even 
in artificial oils. Further examination revealed the fact that in both samples these esters 
were not linalyl acetate, as should be the case in an artificial bergamot oil, but mostly 
bodies of no value for the odour, namely, phthalic acid esters in one sample (probably 
diethyl phthalate) and glyceryl acetate in the other. As both oils contained about 70 p.c. 
of these bodies respectively, the proof of their presence was easy, in spite of the 
smallness of the samples at our disposal. Glyceryl acetate was isolated by shaking out 
with a 5 p.c. solution of alcohol and was recognized 7.a. by the high sap. value (676), 
whereas in the other oil the acid, which did not pass over with steam in the determination 
of the acid number II (Report October 1910, p. 61), was identified as phthalic acid (m.p. 
203°; m. p. of the anhydride obtained by sublimation 130°; fluorescein reaction). 
As mentioned above, both samples contained about 70 p.c. of these esters, that 
is to say such an extent that one cannot speak of artificial bergamot oils any longer, 
but more correctly of cheap and — from the point of view of their strength — valueless 
esters which had been perfumed more or less cleverly so as to resemble bergamot oil. 
Such concoctions have, needless to say, nothing in common with a scientifically pre- 
pared artificial bergamot oil.. 
Lemon Oil. [In our last Report (page 59) we communicated a process elaborated 
by E. Bocker for the determination of hydrocarbon percentage in concentrated lemon 
oils. For this purpose the oil is first freed from citral by means of sodium sulphite; 
thereupon the other aromatic bodies are shaken out with chilled alcohol of 51 p.c. 
strength. The remaining hydrocarbons are calculated by volume, the result is compared 
with the original oil and the percentage thus determined. 
In continuing his studies on the valuation of concentrated lemon oils, Bocker') has 
arrived at the result that a juxtaposition of the percentages of citral and hydrocarbons 
respectively permits of conclusions being drawn as to whether such oils are pure or 
adulterated with citral from lemongrass oil. Experiments with two oils, mixed with 
20 p.c. of citral, however, showed that by this means only about half the amount of 
adulteration can be ascertained, but at all events the minimum of adulteration may 
be determined in this manner. On the same occasion it was once more proved by 
experiment that the citral percentage of concentrated oils is ascertained with greatest 
certainty by the neutral sodium sulphite method as indicated by Burgess. 
In his valuation Bocker starts from the observation that a lemon oil, which has 
been completely freed from hydrocarbons, contains at most 66 p.c. of citral, from which 
deduction he establishes the following table: — 
Highest permissible 
Hydrocarbons Tel percntag Hydrocarbons et centage 
0 p.c. 66° . Dp... 30 p.c. 46,2 p.c. 
5 al ee Or, OD) hes, 42,9 , 
10. ,, 59,4 40 5 39,6 ,, 
‘9-5 BOW. 5, 45 ,, BO;S~4%, 
| BABiA, BO is 33 = 
29 ” 49,5 th 
1) Journ. f. prakt. Chem. i. 90 (1914), 393. 
2* 
