— 37 — 
ripeness of the fruit, and it reaches the lowest points when those 
fruits are worked up which had remained over-ripe on the trees, and 
also in the oil which has been pressed from the early-ripe spring fruit. 
Since the beginning of April last, only oils have been produced the 
rotatory power of which, in the course of time, up to June, fell from 
58^ to 55^^ and even 54^'; on the other hand, the citral- content of 
the oils increases, and the quality of the oils must be characterised 
as remarkabh^ fine. 
The discussion in our last Report of the work on oil of lemon 
bv Burgess and Child, has induced the London Essence Company 
(in whose employ those two gentlemen are as chemists) to return to 
the subject^). Now there occurs in this communication the statement, 
that both citronellal and phellandrene are certainly not present in 
normal oils of lemon, whilst the presence of citronellol, or one of its 
esters, is very probable. As citronellal has been detected in lemon 
oil not once, but several times, and that by various observers, and 
as the presence of phellandrene has been observed repeatedly in our 
laboratories, the above statement is in the first place somewhat 
remarkable, the more so in face of the absence of all information as 
to what might have led the earlier investigators to their erroneous 
observations? So long, therefore, as strict proof to the contrary is 
not produced, or the cause of the error cannot be disclosed, — so 
long will citronellal and phellandrene have to be included in the con- 
stituents of lemon oil, whether the chemists of the London Essence 
Company have detected these bodies in the oil, or not. 
Furthermore, exception is taken to our statement that, according 
to Burgess and Child, octyl and nonyl aldehydes have a pronounced 
influence on the production of the aroma of lemon oil. The fact 
that we refrained from literally quoting the statements by Burgess 
and Child, makes it already evident that we only wished to lay 
stress on the presence of these two aldehydes in lemon oil, but w^e 
did not in the least wish to assert that they have a special influence 
on the strength or fineness of the aroma of lemon oil. That the 
alcohols and esters also are not without importance for the aromatic 
effect, is a matter which we do not by any means desire to deny. 
With regard to the citral-content, we see no reason why we 
should alter the opinion expressed by us, that, according to Burgess 
and Child, lemon oil contains 4 to 7 per cent citral. It is fairly 
probable that a somewhat smaller proportion will be found by a 
modified process, than if the determination were made with lemon 
oil itself; for the rest, the determination of the "citral" -content in 
^) The Chemist and Druggist 60 (1902), 812. 
