— 34 — 
the oil described by Burgess. Gulli, namely, found: d^go 0,851, and 
~\~ 80° 50', and for another oil also prepared from ''cedrmi'\ 
^15° 0.850, and -4- 79°. 
The author further found that the oil of sweet lemon (derived from 
Citrus Limonuin diilcis) represents an excellent adulterant of citron oil, 
for mixtures of equal quantities of common lemon oil, or sweet lemon 
oil, with oil of sweet orange, possessed properties almost identic with 
those of citron oil. But such mixtures can immediately be distinguished 
from genuine citron oil by the fact that they are perfectly clear, 
whilst citron oil soon after preparation becomes turbid, with separation 
of fine white crystals of the form of small needles. 
Dr. Gulli was good enough to send us samples of the two above- 
mentioned oils prepared by him. Unfortunately, both oils reached 
us in a turbid condition owing to crystals having separated out, and 
we are therefore unable to accept such behaviour as characteristic of 
citron oil alone. After removing the crystalline precipitate by filtration, 
we found for the cedrini oil: dj^^o = 0,8541, aD2i° = -|- 81° 7' 
and nj)2o° = i»47 48o; and for the oil of sweet lemon: =0,8579; 
aj)2t° = 64° 1 5^ and np2o° = Ij47 5^8, whilst Gulli gives for the 
latter d = 0,856 and — -|- 64° 30'. Our observations consequently 
agree fairly well. 
But the determination of the specific gravity and the rotatory 
power alone is not sufficient to distinguish genuine from adulterated 
citron oil; this is clear from a further article on this subject by the 
chemists of the London Essence Company i). In their opinion, adul- 
teration can readily be detected in the same manner as already 
proposed by Burgess and Child for lemon oil, viz., by separating 
the oil to be tested into different carefully measured fractions, and 
determining the physical constants of such fractions. For a sample 
of pure citron oil with d^50 = 0,852, a^ = -\- 80° 5' and n^^ = 1,4749, 
the authors give the following as typical values: 
Fraction OCj) n^ Aldehyde-content 
10 per cent + 85° 55^ I4730 — 
80 „ „ +86° 5' 1,4735 - 
7 4-16^30' 1,4806 53 per cent. 
The two first fractions would therefore have a higher rotatory 
power than the original oil, which would not be the case if the oil 
had been adulterated. The chemists of the London Essence Company 
also refer to the presence of crystals as being a characteristic of 
citron oil. 
^) The Chemist and Druggist 62 (1903), 57. 
