50 
PRESIDENT’S ADDRESS — SECTION R. 
change in proportion of volume. Also, the alcoholic solution must 
not alter the colour of litmus paper, nor assume a brown or violet 
colour by the addition of a drop of solution of ferric chloride, showing 
absence of phenols. 
Phellandrene — This is one of several true terpenes represented 
by the formula C 10 H lfi . It is capable of existing in two optical 
modifications, one turning the plane of polarised light to the left and 
the other to the right. It boils at about 170°. 
With many writers on eucalyptus oils it is a veritable pariah 
amongst terpenes, its presence disqualifying a eucalyptus oil. Those 
who object to its presence look upou it as a mere diluent of eucalyptus 
oil, stating that it possesses no medicinal properties that are not 
possessed by the terpenes of the cheaper oil of turpentine. At the 
same time we have no direct evidence that the terpene phellandrene 
is not a therapeutically active constituent of eucalyptus oil. Jn some 
it is entirely absent, in most it exists in greater or less quantity. It 
may be readily detected in an oil if treated with a concentrated 
solution of sodium nitrite. If a few drops of glacial acetic acid be 
added to the mixture, a copious formation of crystals of phellandrene 
nitrite (of a whitish colour) ensues. 
Aldehydes. — The pungent and irritating odour of the oils of some 
species is owing to the presence of aldehydes, and fortunately there 
is no real difficulty in removing them by rectification. These cough- 
producing substances should always be removed, and 1 have heard a 
curious reason why manufacturers retain them in tome oils. It is 
that the public like a pronounced flavour — some u fire ” in the oil, in 
fact ; hut 1 hope that the taste of the public will become enlightened, 
for these aldehydes may cause most serious results in persons 
suffering from throat, bronchial, or lung troubles, while I know of no 
compensating value whatever. 
At the same time there are some sweet-scented and non -injurious 
aldehydes — e.g citronellon, which forms so large a proportion of the 
oil of E. maculatci, var. citriodora . 
Various eucalyptus oils contain other constituents, but they are 
of minor importance. 
OTHER ESSENTIAL OILS. 
Most of the work on Australian essential oils other than 
Eucalyptus, has been done on Melaleuca . The oils of M. decussata , 
R. Br., M. ericifolia , Sin. ; M. uncinala , R. Br. ; and M. Wihoni , 
F. v. M., have been examined by Wittstein and Mueller.* M. ericifolia , 
Sm., and M. tin arid folia. Sin., have been examined polarimetrieally by 
Dr. Gladstonef, while other oils have been examined less thoroughly. 
In view, however, of recent researches into the constitution and 
properties of essential oils, it is very desirable that the Melaleuca oils 
should be examined de novo . The plants are amongst the commonest 
of the Australian vegetation, so there need be no real difficulty in 
getting supplies of various oils true to name. Schiminel and Co.J 
have published brief notes in regard to three of them, hut beyond 
* “ Wittstein’s Organic Constituents of Plants,” (Mueller’s trans., p. 152). 
f Journ. Chem. Soc., xvii., 3. + Bericht, Ajril, 1892, p. GO. 
