21 
content of sesquiterpene, dissolve clear, or at most with a very slight 
turbidity, in 8 1 to 83 per cent, alcohol, v^hilst with oils which have 
been mixed with only very small quantities of petroleum, the turbidity 
does not diminish even when 85 per cent, alcohol is used. 
But along with the gradual decline in the price of citronella oil 
there was a great increase in the number of insoluble oils which were 
submitted to us for examination, and we found that even the somewhat 
stronger alcohol recommended by Parry did not regularly suffice for 
solution. The oils differed from unadulterated oils barely in specific 
gravity, but little in rotatory power, most in the index of refraction 
which was essentially lower than otherwise. Now, when in a specially 
striking case a rather large sample was placed at our disposal, we 
determined the physical constants of the portion insoluble in 80 per cent, 
alcohol. We found: dj50 0,8411; a-^ — 11° 21'; n^go^ 1,46872. The 
separated insoluble oil did not dissolve in 10 volumes 90 per cent, 
alcohol, but made a cloudy solution wdth about 8 volumes 95 per cent, 
alcohol. In order to obtain further data, a part of the original oil 
was carefully fractionated with water vapour; for the two fractions first 
passing over we ascertained the following constants: 
^15° «D ^D20° 
I 0,8145 — 19^6' 1,44 741, 
II 0,8278 — 21^24' i,4537i» 
whilst a pure Ceylon citronella oil taken for comparison, and reduced 
into fractions of equal quantity, gave the following figures for the more 
volatile portions: 
I 0,8599 —50^44' 1,47058, 
II 0,8608 —48^46' 1,47156. 
It follows that to the citronella oils which do not pass the solubility- 
test, a comparatively highly volatile body, of very low specific gravity, 
and an exceptionally low index of refraction, has been added. It is 
open to doubt, whether it is here a question of adulteration with 
a fraction of petroleum or petroleum ether, or of the addition of resin 
spirit. Parry and Bennett who simultaneously with us made similar 
observations on adulterated citronella oil, and who have already- 
published these ^), are inclined to believe that it is a question of 
adulteration with resin spirit, without, however, giving proofs, which in 
any case it would be very difficult to supply. In a short time we 
shall have an abundance of material for examination, and we hope 
then to be able to clear up this question to some extent. 
^) The Chemist and Druggist 62 (1903), 88. 
