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lemon oil suffers from this disadvantage, that it not only indicates 
the quantity of the citral actually present, but also that of the other 
bodies of an aldehyde- or ketone-like character, which, in addition 
to citral, are present in lemon oil. For this reason, this determination 
has only a relative value. 
What we mentioned with regard to the index of refraction is no 
doubt due to a misunderstanding; we connected this statement with 
lemon oil itself, but not with fractionated oil. We therefore wish to 
correct the remarks in our April Report in so far, that we add, "that 
the individual fractions of lemon oil show an increasing index of 
refraction, and that, according to Burgess and Child, this increase 
can be utilised for the purpose of detecting possible additions to 
lemon oil". We have searched in vain in Burgess and Child's 
work for the statement (which is made in the rejoinder), that the 
refractive index of normal oil of lemon fluctuates between 1,4750 
and 1,4760; the values for pure oil mentioned in table 2 of the 
original do not all agree with this. 
Since the publication of our April Report, while continuing our 
work in connection with the detection of pinene, we have only had 
an opportunity of examining two oils, obtained from a reliable source, 
which had been pressed specially for the purposes of our examination. 
One of these (di^o 0,8595; aj) 56° 43'; UDaoO 1,47587) was pressed 
entirely from over-ripe winter lemons; the other (dj^o 0,860; aD ~(~53°3'5 
^D2oO i>47568) partly from ripe winter lemons, partly from spring lemons 
(bianchetti). As the samples were comparatively small, we only succeeded 
in obtaining a first fraction, which in both cases was still slightly dex- 
trogyre, but in which pinene could be detected respectively by its 
nitrosochloride, and its nitrolbenzylamine. 
We subsequently fractionated a considerable quantity of terpenes 
from lemon oil, in order to obtain a further knowledge of the laevogyre 
hydrocarbon therein contained. The gentlemen of the London Essence 
Company are surprised that we have been able to isolate this laevogyre 
body without having used a Young's twelve-beaded dephlegmator, 
and they show a considerable amount of interest to learn how we 
have done this. We do not, however, feel called upon to give them 
information on the apparatus used by us, which apparatus, as they 
can learn from the results of our work, must have decided advantages 
over Young's dephlegmator, even when the latter has twelve beads. 
For we have even succeeded in separating from this low -boiling 
laevogyre first fraction, further fractions, which at the boiling point of 
pinene show a decidedly higher laevogyration ( — 13° to — 14°) 
than Burgess and Child have observed, — and also another frac- 
tion boiling still a little higher, which is even stronger laevogyre 
