_Oleum Aurantii florum_; _Oil or Essence of Neroli_; F. _Essence de
Néroli_; G. _Neroliöl_.
=Botanical Origin=—_Citrus vulgaris_ Risso. (See page 124.)
=History=—Porta, the Italian philosopher of the 16th century referred
to (p. 118), was acquainted with the volatile oil of the flowers of
the citron tribe (“_Oleum ex citriorum floribus_”), which he obtained
by the usual process of distillation, and describes as possessing
the most exquisite fragrance. That distilled from orange flowers
acquired a century later (1675-1685) the name of _Essence of Neroli_
from Anne-Marie de la Trémoille-Noirmoutier, second wife of Flavio
Orsini, duke of Bracciano and prince of Nerola or Neroli. This lady
employed it for the perfuming of gloves, hence called in Italy _Guanti
di Neroli_.[491] It was known in Paris to Pomet, who says[492] the
perfumers have given it the name of _Neroli_, and that it is made in
Rome and in Provence.
=Production=—Oil of Neroli is prepared from the fresh flowers of the
Bigarade or Bitter Orange by the ordinary process of distillation with
water, conducted in small copper stills. The flowers of all the allied
plants are far less aromatic. The water which distills over with the
oil constitutes, after the removal of the latter from its surface, the
_Orange Flower Water_ (_Aqua aurantii florum vel Aqua Naphæ_)[493] of
commerce. The manufacture is carried on chiefly in the south of France
at Grasse, Cannes, and Nice. The yield is about 0·6 to 0·7 per cent. of
oil from fresh flowers, as stated by Poiteau et Risso.[494] The flowers
of the sweet orange afford but half that amount of oil.
=Description and Chemical Composition=—Oil of Neroli as found in
commerce is seldom pure, for it generally contains an admixture of the
essential oil of orange-leaf called _Essence of Petit Grain_.
By the kind assistance of Mr. F. G. Warrick of Nice, we have obtained a
sample of Bigarade Neroli of guaranteed purity, to which the following
observations relate. It is of a brownish hue, most fragrant odour,
bitterish aromatic taste, and is neutral to test-paper. Its sp. gr.
at 11° C. is 0·889. When mixed with alcohol, it displays a bright
violet fluorescence, quite distinct from the blue fluorescence of a
solution of quinine. In oil of Neroli the phenomenon may be shown most
distinctly by pouring a little spirit of wine on to the surface of
the essential oil, and causing the liquid to gently undulate. The oil
is but turbidly miscible with bisulphide of carbon. It assumes a very
pure, intense, and permanent crimson hue if shaken with a saturated
solution of bisulphide of sodium. Examined in a column of 100 mm. we
observed the oil to deviate the ray of polarized light 6° to the right.
[491] Menagio, _Origini della Lingua Italiana_, 1685; _Dict. de
Trévoux_, Paris, vi. (1771) 178.—The town of Nerola is about 16 miles
north of Tivoli.
[492] _Histoire des Drogues_, 1694. 234. ii.
[493] Naphé or Naphore—according to Poiteau et Risso, _Hist. Nat. des
Orangers_ 1873. 211, these names perhaps originated in Languedoc.
[494] _L. c._ 211.
Subjected to distillation, the larger part of the oil passes over at
185°-195° C.; we found this portion to be colourless, yet to display in
a marked manner the violet fluorescence and also to retain the odour of
the original oil. The portion remaining in the retort was mixed with
about the same volume of alcohol (90 per cent.) and some drops of water
added, yet not sufficient to occasion turbidity. A very small amount
of the crystalline _Neroli Camphor_ then made its appearance, floating
on the surface of the liquid; by re-solution in boiling alcohol it was
obtained in crystals of rather indistinct form. The redistilled oil
gave no camphor whatever.
Neroli Camphor was first noticed by Boullay in 1828. According to
our observations it is a neutral, inodorous, tasteless substance,
fusible at 55° C., and forming on cooling a crystalline mass. The
crystallization should be effected by cooling the hot alcoholic
solution, no good crystals being obtainable by slow evaporation or by
sublimation. The produce was extremely small, about 60 grammes of oil
having yielded not more than 0·1 gramme. Perhaps this scantiness of
produce was due to the oil being a year and a half old, for according
to Plisson[495] the camphor diminishes the longer the oil is kept.[496]
We were unable to obtain any similar substance from the oils of
bergamot, petit grain, or orange peel.
_Orange Flower Water_ is a considerable article of manufacture among
the distillers of essential oils in the south of Europe, and is
imported thence for use in pharmacy. According to Boullay[497] it is
frequently acid to litmus when first made,—is better if distilled in
small than in large quantities, and if made from the petals _per se_,
rather than from the entire flowers. He also states that only 2 lb. of
water should be drawn from 1 lb. of flowers, or 3 lb. if petals alone
are placed in the still. As met with in commerce, orange flower water
is colourless or of a faintly greenish yellow tinge, almost perfectly
transparent, with a delicious odour and a bitter taste. Acidulated with
nitric acid, it acquires a pinkish hue more or less intense, which
disappears on saturation by an alkali.
=Uses=—Oil of Neroli is consumed almost exclusively in perfumery.
Orange flower water is frequently used in medicine to give a pleasant
odour to mixtures and lotions.
=Adulteration=—The large variation in value of oil of Neroli as shown
by price-currents[498] indicates a great diversity of quality. Besides
being very commonly mixed, as already stated, with the distilled oil
of the leaves (_Essence de Petit Grain_)[499], it is sometimes reduced
by addition of the less fragrant oil obtained from the flowers of
the Portugal or Sweet Orange. In some of these adulterations we must
conclude that orange flower water participate: metallic contamination
of the latter is not unknown.
[495] _Journ. de Pharm._ xv. (1829) 152.
[496] Yet we extracted it from an old sample labelled “_Essence de
Néroli Portugal—Méro._”
[497] _Bulletin de Pharm._, i. (1809) 337-341.
[498] Thus in the price-list of a firm at Grasse, Neroli is quoted as
of _four_ qualities, the lowest or “commercial” being less than half
the price of the finest.
[499] We have been informed on good authority that the Neroli commonly
sold contains ⅜ of Essence of Petit Grain, and ⅛ of Essence of
Bergamot, the remaining ⁴/₈ being true Neroli.
Other Products of the genus Citrus.
=Essence or Essential Oil of Petit Grain=—was originally obtained by
subjecting little immature oranges to distillation (Pomet—1692); but
it is now produced, and to a large extent, by distillation of the
leaves and shoots either of the Bigarade or Bitter Orange, or of the
Portugal or Sweet Orange. The essence of the former is by far the
more fragrant, and commands double the price. Poiteau and Risso[500]
state that the leaves of the Brigaradier with bitter fruit are by far
the richest in essential oil among all the allied leaves; they are
obtained in the lemon-growing districts of the Mediterranean where
the essence is manufactured. Lemon-trees being mostly grafted on
orange-stocks, the latter during the summer put forth shoots, which
are allowed to grow till they are often some feet in length. The
cultivator then cuts them off, binds them in bundles, and conveys them
to the distiller of _Petit Grain_. The strongest shoots are frequently
reserved for walking-sticks. The leaves of the two sorts of orange are
easily distinguished by their smell when crushed. Essence of Petit
Grain, which in odour has a certain resemblance to Neroli, is used in
perfumery and especially in the manufacture of Eau de Cologne.
According to Gladstone (1864) it consists mainly of a hydrocarbon
probably identical with that from oil of Neroli.
=Essential Oil of Orange Peel=—is largely made at Messina and also
in the south of France. It is extracted by the sponge-, or by the
_écuelle_-process, and partly from the Bigarade and partly from the
Sweet or Portugal Orange, the scarcely ripe fruit being in either
case employed. The oil made from the former is much more valuable
than that obtained from the latter, and the two are distinguished in
price-currents as _Essence de Bigarade_ and _Essence de Portugal_.
These essences are but little consumed in England, in liqueur-making
and in perfumery. For what is known of their chemical nature, the
reader can consult the works named at foot[501].
=Essence of Cedrat=—The true Citron or Cedrat tree is _Citrus medica_
Risso, and is of interest as being the only member of the Orange tribe
the fruit of which was known in ancient Rome. The tree itself, which
appears to have been cultivated in Palestine in the time of Josephus,
was introduced into Italy in about the 3rd century. In A.D. 1003 it
was much grown at Salerno near Naples, whence its fruits were sent as
presents to the Norman princes[502].
[500] _Loc. c._, edition of 1873. 211.
[501] Gmelin, _Chemistry_, xiv. (1860) 305. 306: Gladstone, _Journ.
of Chem. Soc._ xvii. (1864) 1: Wright (and Piesse) in _Yearbook of
Pharmacy_, 1871. 546; 1873. 518; _Journ. of Chem. Soc._ xi. (1873)
552, &c. We may moreover point out the existence of a crystallized
constituent of the oil of orange peel from the island of Curaçao. It
was noticed as long ago as the year 1771 by Gaubius: “Sal aromaticus,
nativus, ex oleo corticum mali aurei Curassavici,” in his book,
“Adersariorum varii argumenti, lib. unus.” Leidae, 1771. 27.
[502] Gallesio, _Traité du Citrus_, 1811. 222.
At the present day, the citron appears to be nowhere cultivated
extensively, the more prolific lemon tree having generally taken its
place. It is however scattered along the Western Riviera, and is also
grown on a small scale about Pizzo and Paola on the western coast of
Calabria, in Sicily, Corsica, and Azores. Its fruits, which often weigh
several pounds, are chiefly sold for being candied. For this purpose
the peel, which is excessively thick, is salted and in that state
shipped to England and Holland. The fruit has a very scanty pulp[503].
Essence of Cedrat which is quoted in some price-lists may be prepared
from the scarcely ripe fruit by the sponge-process; but as it is more
profitable to export the fruit salted, it is very rarely manufactured,
and that which bears its name is for the most part fictitious.