COSMETICS.
Skin cosmetics; Toilet vinegars; Vinaigre de Bully; Vinaigre
de toilette à la rose; Vinaigre de toilette à la violette 324
Vinaigre de toilette héliotrope; Vinaigre de toilette orange;
Vinaigre de toilette; Aromatic vinegar; English aromatic
vinegar 325
Toilet vinegar; Washes; Virginal milk (Lait virginal);
Rose milk (Lait de rose) 326
Almond milk (Lait d'amandes amères) 327
Lily milk (Lait de lys); Perfumed glycerin with rose odor;
Perfumed glycerin with fruit odor; Perfumed meals and
pastes; Farin de noisette (nut meal) 328
Farin d'amandes amères (almond meal); Pate d'amandes
au miel (honey almond paste); Poudre de riz à la rose 329
Poudre de riz héliotrope; Poudre de riz orange; Poudre de
riz muguet 330
Poudre de riz ixora; Poudre de riz bouquet; Cold creams
and lip salves; Cold cream; Vaseline cold cream 331
Glycerin cream; Crême de concombre; Glycerin gelée;
Glycerin jelly 332
Cream of roses; Boroglycerin cream; Recamier cream;
Preparations for chapped hands 333
Wash for the hands; Nail powder; Lip-salves 334
Paints; Pulverulent paints (powders); "Blanc fard" or
"Blanc français" 335
Mixtures for powders; Coloring substances for powders;
Powder for coloring intensely red; Solid paints; Ordinary
red paint (rouge) 336
Fine red paint (rouge); White paint; Preparation of paints 337
Red stick-paint (stick rouge); Moulding the rouge into sticks 339
White stick-paint; Rouge en feuilles; Liquid paints; Liquid
rouge 340
White liquid paint; Fat paints 341
Crême de Lys; Crême de rose 342
INDEX 343
A PRACTICAL TREATISE
ON THE
MANUFACTURE OF PERFUMERY.
CHAPTER I.
HISTORICAL NOTICE OF PERFUMERY.
Nature has implanted in man the instinct of finding the odor
accompanying decay and putrefaction insufferable, of fleeing from it,
and of going in quest of fragrant odors. Hence, in ancient times,
perfume substances were highly esteemed, and an offering of them was
considered a sign of the most profound reverence and homage. The early
nations of the Orient especially used perfume substances in such
profusion that the consumption of them by the finest lady of to-day
must be called a comparatively moderate one. This may, however, be
readily explained, for, on the one hand, the majority of plants which
produce the most agreeable perfumes in larger quantity are indigenous
to the Orient; and, on the other, the excessive exhalations from the
human body, caused by the hot climate, forced the people to search for
means to remove, or at least to cover, the disagreeable odor arising
therefrom.
Since fragrant odors were agreeable to human beings, it was believed
that they must be welcome also to the gods, and, to honor them, perfume
substances were burned upon the altars. Besides, as an offering to
the gods, perfume substances were extensively used by many nations,
especially by the Egyptians, for embalming the dead, the process
employed by the latter having been transmitted to us by the ancient
authors Herodotus and Diodorus.
Furthermore, a desire for ornamentation and to give to the face and
body as pleasing an appearance as possible, is common to all mankind.
To be sure, the ideas of what constitutes beauty in this respect
have varied at different times and among the various nations. But,
independent of the savage races, who consider painting and tattooing
the body and face an embellishment, and taking into consideration only
the earliest civilized nations, it is astonishing how many arts of the
toilet have been preserved from the most ancient historical times up
to the present. "In the most ancient historical times, people perfumed
and painted, frizzed, curled, and dyed the hair as at present, and, in
fact, the same cosmetics, only slightly augmented, which were in use
hundreds, nay, thousands, of years ago are still employed to-day."[1]
It is especially woman, who everywhere exercises the arts of the
toilet, while, with the exception of perfumes and agents for the hair,
man is but seldom referred to as making use of cosmetics. The young
girls of ancient Egypt used red and white paints, colored their pale
lips, and anointed their hair with sweet-scented oils; they dyed their
eyelashes and eyelids black to impart a brighter lustre to the glance
of the eye, and the mother of the wife of the first king of Egypt is
said to have already composed a receipt for a hair-dye.
[1] Paschkis, Kosmetik für Aerzte. Wien, 1890.
From the Egyptians, the practices of the toilet, like many other
things, were transmitted to the Jews. In Egypt, the Hebrew woman had
known the sweet-scented flower of the henna bush, and, finding it also
in Judea, it served her as a perfume. In the Bible the henna flower is
called _kopher_, in Greek _kypros_, and the Cyprian salve, mentioned by
Pliny, was prepared by boiling henna flowers in oil and then expressing
them.
Painting the face was also practised by the Hebrew women, reference
being made to it in II. Kings ix. 30, and Jeremiah v. 30, while
painting of the eyes is mentioned in Ezekiel xxiii. 40.
The number of perfume substances known to the ancient Hebrews was but a
limited one, they consisting, besides the above-mentioned henna flower,
chiefly of a few gum-resins, especially bdellium, olibanum and myrrh.
In ancient times olibanum was, without doubt, the most important
perfume-substance. It was introduced into commerce by the Phoenicians,
and, like many other substances, it received from them its name,
which was adopted by other nations. Thus, the Hebrews called the tree
_lebonah_, the Arabs, _lubah_, while the Greeks named it, λιβανός
and the resin derived from it, the celebrated frankincense of the
ancients, λιβανωτόςτς, Latin, _olibanum_. Regarding the mode of gaining
the olibanum, some curious ideas prevailed in ancient times. Thus,
Herodotus writes: "Arabia is the only country in which olibanum grows,
as well as myrrh, cassia, cinnamon and lederum. With the exception
of myrrh, the Arabs encounter many difficulties in procuring these
products. Olibanum they obtain by burning styrax, for every olibanum
tree is guarded by a number of small-sized winged serpents of a
variegated appearance, which can be driven away by nothing but styrax
vapors." According to Pliny, who gives a very full account of olibanum,
_Arabia felix_ received its by-name from the abundance of olibanum and
myrrh found there. He states that olibanum grows in no other country
besides Arabia, but it is not found in every part of it. About in the
centre, upon a high mountain, he continues, is the country of the
Atramites, a province of the Sabeans, from which the olibanum region is
distant about eight days' journey. It is called Saba and is everywhere
rendered inaccessible by mountains, a narrow defile, through which the
export is carried on, leading into an adjoining province inhabited by
the Mineans. In Saba itself were not more than 300 families, called the
saints, who claimed the cultivation of olibanum as a right of heritage.
When making the incisions in the trees, and while gathering the
olibanum, the men were prohibited from having intercourse with women
and from attending funerals. Notwithstanding the fact that the Romans
carried on war in Arabia, none of them had ever seen an olibanum tree.
When there was less chance of selling the olibanum, it was gathered but
once in the year, but since the increase in the demand, it was gathered
twice, first in the fall and again in the spring, the incisions in
the trees having been made during the winter. The collected olibanum
was brought upon camels to Sabota, where one gate was open for its
reception; to turn from the road was prohibited under penalty of death.
The priests took one-tenth by measure for the god Sabin, sales not
being allowed until their claim was satisfied. The olibanum could be
exported only through the territory of the Gebanites, whose King also
levied tribute.
Pliny further states that the Arabs did not steal one from another, but
for fear of loss those employed in the stores of Alexandria were forced
to go naked with the exception of a clout which was sealed. A mask and
a thick net were thrown over the head.
To us the practice of anointing the entire body, customary among the
ancients, appears very singular. Old Egyptian sculptures represent
the guests being anointed at the meal. Among the Jews we find a holy
oil with which Aaron and his sons were anointed to consecrate them to
the priesthood, Moses prescribing for this holy anointing oil, myrrh,
cinnamon, calamus, and oil from the olive tree. Other persons were
prohibited from imitating or using this holy oil. The anointing of
kings was introduced later on. Though it was prohibited to imitate and
use the holy oil, this prohibition did not refer to anointing with oil
in general.
That the Greeks also set a high value upon anointing with oil is
plainly seen from Homer. When Telemachus visited Nestor, Polycaste,
Nestor's youngest daughter, bathed him and anointed him with oil, and
when he was the guest of Menelaus, the maids of the latter performed
the same service for him, while for Ulysses returning as a beggar, the
aged Euryclea prepared a foot-bath and anointed him.
By the addition of fragrant substances to the oil, the sweet-scented
ointment, _myron_, originated. While the anointing with simple oil
evidently served as a hygienic measure after the bath, and especially
for men in the gymnasium, and before a combat, with the Greeks,
ointments were an article of luxury. In Socrates' time the use of
sweet-scented ointments had reached such an extent, that Xenophon
caused him to speak against it, but, as is the case with all such
lectures against fashion, without the slightest success. In Athens the
luxury was carried so far that the bacchanalians anointed each part of
their body with a special ointment. The oil extracted from the palm
was thought best adapted to the cheeks and the breasts; the arms were
refreshed with balsam-mint; sweet marjoram supplied an oil for the
hair and eyebrows; and wild thyme for the knee and neck. Although to
us it would be repugnant to have the entire body anointed, in Athens
it was considered beautiful to be glossy with ointments. It is said of
Demetrius Phalereus, that in order to appear more captivating, he dyed
his hair yellow, and anointed the face and the rest of his body.
From the Asiatics and Greeks the Romans also learned the use of
ointments. Pliny cannot say at what time they were introduced in Rome,
but states that after the conquest of Asia and the defeat of the King,
Antiochus, in the year 565, after the building of Rome, the censors
issued an edict prohibiting the sale of foreign ointments. However,
this edict was of no use, and the practice spread more and more,
Pliny speaking very bitterly about it. Regarding this extravagance
in ointments, Plutarch says: "Frankincense, cinnamon, spikenard, and
Arabian calamus are mixed together with the most careful art and sold
for large sums. It is an effeminate pleasure and has spoiled not only
the women but also the men, who will not sleep even with their own
wives if they do not smell of ointments and powders." Plutarch further
mentions an incident which must have created a sensation even in
luxurious Rome, as otherwise it would scarcely have been chronicled for
the benefit of posterity. Nero one day anointed himself with costly
ointments and scattered some of them over Otho. The next day Otho gave
Nero a banquet, and laid in all directions gold and silver tubes, which
poured forth expensive ointments like water, thoroughly saturating the
guests.
Directions for preparing ointments are contained in Theophrastus's
work "On Perfumes," in Dioscorides's "Medica materia," and Pliny's
"Historia naturalis." Dioscorides's receipts are the fullest. According
to Pliny, a distinction was made between the juice and the body, the
latter consisting of the fat oils and the former of the sweet-scented
substances. In preparing the ointments, the oil together with the
perfuming substances were heated in the water-bath. For instance,
rose ointment was, according to Dioscorides, prepared by mixing 5½
lbs. of bruised _Andropogon Schœnanthus_ with a little water, then
adding 20½ lbs. of oil and heating. After heating the oil was filtered
off, and the petals of one thousand roses were thrown into the oil,
the hands with which the rose leaves were pressed into the oil being
previously coated with honey. When the whole had stood for one night,
the oil was strained off and when all impurities had settled, it was
brought into another vessel and fresh rose leaves introduced, the
operation being several times repeated. However, according to the
opinion of the ancient ointment makers, no more odor was absorbed by
the oil after the seventh introduction of rose leaves. To fix the odor,
resins or gums were added to the ointments.
A process of distilling volatile oils was also known, the
odoriferous matter being caught by spreading wool over the heated
perfume-substances. The wool was afterwards subjected to pressure. This
process, of course, involved great loss and was available only for
substances containing much volatile oil.
Dioscorides also gives directions for making animal fats suitable for
the reception of perfumes. Beef-tallow, deer-fat, or the marrow of
animals was freed from all membranes, melted together with a little
salt in an entirely new vessel, and then poured into clean water, where
it was washed by rubbing with the hands, the water being frequently
renewed. Then it was boiled with equal parts of sweet-scented wine,
and after taking it from the fire it was allowed to stand over night.
The next day the cold fat was again boiled in a new vessel, with
sweet-scented wine, this operation being repeated until the fat had
lost every trace of disagreeable odor, when it was brought in contact
with the perfumes.
The consumption of perfume-substances by the ancient Romans must have
been enormous. The trade of the ointment makers (_ungentarii_) was so
extensive that the large street _Seplasia_ in old Capua was entirely
taken up by it, and the business must have paid well since the prices
realized were very high. However, in ancient times the business cannot
have been very agreeable, at least not in Greece, as shown by a passage
in Plutarch's Life of Pericles: "We take pleasure in ointments and
purple, but consider the dyers and ointment makers bondsmen and
mechanics."
Red and white paints, in the form of powder as well as of paste, were
extensively used by the Roman ladies. Chalk and white lead served for
white paint, and minium and carmine for red. Lovers preferred white
paints, a pale color being more becoming to them:--
"Palleat omnis amans; hic est
color aptus amanti."--(_Ovid._)
For black paints for the eyebrows roasted ant eggs or soot were used.
The Roman ladies paid as much attention to their natural, and also
false, hair as the fair ones of to-day. They curled their hair with
heated iron instruments, and perfumed them with fragrant oil. If from
age, sorrow, or other reasons, the hair was no longer black, it was
dyed, and it seems that a considerable number of hair-dyes were known
in Rome, amongst them some which are still employed to-day, such as
green nutshells and acetate of lead.
After the Romans had seen the blonde German maidens, blonde and red
hair became the fashion. To dye the hair blonde sharp alkaline soaps
were chiefly used. However, this or some other hair-dye seems to have
been very injurious, as it caused the hair to come out. The satirists
ridiculed this as well as the wigs, which were worn by men and women to
hide baldness, or on account of the color which could not be attained
by dyes.
Depilatories were also known to the Romans, the agents employed being
called _psilothrum_ and _dropax_. They were of vegetable origin, but
it is not exactly known from which plants they were derived.
For cleaning the teeth the Roman ladies used a dentifrice which does
not seem very inviting to us. It consisted of a urine imported from
Spain (_dens hiberna defricatus urina_). To perfume the breath or to
hide its bad odor, mouth-washes, perfumed with saffron, roses, etc.,
were used, or myrrh, mastic from Chios or perfumed pastilles were
chewed.
We know but little regarding the use of perfumeries and cosmetics in
the Middle Ages. In the wars during the migrations of the nations,
but little thought was very likely given to them, but as soon as the
nations became again settled and made sufficient progress in culture,
the taste for perfumes and other pleasures of life no doubt returned.
Our knowledge in this respect is limited to what is contained in the
works of physicians of the first centuries. Later on we find receipts
for cosmetics in the writings of Arabian physicians, such as Rhazes
(end of the 9th to the commencement of the 10th century), Avicenna
(end of the 10th to the commencement of the 11th century), and Mesuë
(11th century). To the 11th century also belong the works of the
celebrated Trotula, "_De mulierum passionibus_," "_Practica Trotulae
mulieris Salernitanae de curis mulierum_," and "_Trotula in utilitatem
mulierum_," all of which contain receipts for cosmetics. In the
14th century the most celebrated surgeon of the Middle Ages, Guy de
Chanlios, did not consider it beneath his dignity to devote a section
of his "Grande Chirurgie" to cosmetics. However, it was only in the
16th century that perfumes and cosmetics came again into prominent
notice in Italy, which at that time was the country of luxury and art.
Giovanni Marinello,[2] a physician, in 1562 wrote a work on "Cosmetics
for Ladies," which he dedicated to the ladies Victoria and Isabella
Palavicini. In the preface the author expresses the opinion that it
is only right and pleasing to God to place the gifts bestowed by him
in a proper light and to heighten them. He then proceeds to give
perfumes for various purposes, aromatic baths to keep the skin young
and fresh, means for increasing the stoutness of the entire body and
of separate limbs, and others for reducing them. He further recommends
certain remedies for making large eyes small, and small ones large.
The chapter on the hair is very fully treated. To prevent the hair
from coming out, rubbing with oil, and then washing with sorrel and
myrobalan is recommended. For promoting the growth of the hair, the
use of dried frogs, lizards, etc., rubbed to a powder, is prescribed.
Means for making the hair long and soft and curly are also given, and
others recommended for eyebrows and eyelashes. As depilatories lime
and orpiment are prescribed. Paints are also classed among general
cosmetics. Their use became at this time more and more fashionable, and
not only the face, but also the breast and neck were painted.
[2] Gli ornamenti delle donne, tratti dalle seriture d'una Reina
greca, par M. Giovanni Marinello in Venetia.
Catherine of Medici and Margaret of Valois introduced these arts
of the toilet into France. That country soon became the leader in
this respect, and for many years the greatest luxury in perfumes
and cosmetics prevailed there. The golden age for these articles
lasted from the commencement of the seventeenth to the middle of
the eighteenth century, during which time the _mouche_ or beauty
patch also flourished. "There were at that time hundreds of pastes,
essences, cosmetics, a white balsam, a water to make the face red,
another to make a coarse complexion delicate, one to preserve the fine
complexion of lean persons and again one to make the face like that
of a twenty-year old girl, an _Eau pour nourir et laver les teints
corrodés_ and _Eau de chair admirable pour teints jaunes et bilieux_,
_etc._ Then there were _Mouchoirs de Venus_, further bands impregnated
with wax to cleanse and smooth the forehead; gold leaf was even heated
in a lemon over a fire in order to obtain a means which should impart
to the face a supernatural brightness. For the hair, teeth and nails
there were innumerable receipts, ointments, etc. However, of special
importance were the paints, chemical white, blue for the veins, but,
chief of all, the red or rouge, mineral, vegetable, or cochineal. The
application of rouge was at that time no small affair, it was not only
to be rouged, but the rouge had also to express something--_Le grand
point est d'avoir un rouge qui dise quelque chose_. The rouge had to
characterize its wearer; a lady of rank did not wear the rouge like a
lady of the court, and the rouge of the wife of the bourgeois was not
like either of them nor like that of the courtesan. At court a more
intense rouge was worn, the intensity of which was still increased on
the day of presentation, it being then _Rouge d'Espagne_ and _Rouge
de Portugal en tasse_. It may seem incredible, but for eight days a
violet paint was used and then for a change _Rouge de Serkis_. Ladies,
when retiring for the night applied a light rouge (_un demi rouge_),
and even small girls wore rouge, such being the decree of fashion. The
ladies dyed their eyebrows and eyelashes, and powdered their hair, both
natural and false, for, about 1750, they commenced wearing wigs and
chignons. Powdering was done partially for the purpose of dying the
hair after dressing, and partially for decoration; white, gray, red and
fiery red powders were in vogue."
To that time fashion also ordained an ever-varying routine in the
employment of perfumes; so that the royal apartments were one day
fragrant with the scent of the tuberose and the next with that of amber
and cloves; and so on consecutively, each succeeding day bringing a
change of the reigning odor. In that luxurious age the personal use of
perfumes was not confined to the fair sex, but the effeminate gallants
of the day gloried in perfuming themselves with the favorite scents of
their mistresses or of prominent belles; so that the allegiance was
recognized, not as in more chivalrous times by the knight wearing the
colors of the fair one who had enslaved him, but by his smelling of the
particular odor which she had consecrated to herself.
Philip Augustus, in 1190, granted a charter to the French perfumers,
who had formed a guild. This charter was, in 1357, confirmed by
John, and in 1582 by Henry III., and remained in force until 1636.
The importance of the craft in France is shown by the fact that
under Colbert the perfumers or "_parfumeurs-gantiers_," as they were
called, were granted patents which were registered in Parliament.
In the seventeenth century Montpellier was the chief seat of the
French perfumery industry; to-day it is Paris, and over fifty
millions of francs' worth of perfumery are annually sold there. The
_parfumeurs-gantiers_ had the privilege of selling gloves of all
possible kinds of material, as well as the leather required for them;
they had the further privilege of perfuming gloves and selling all
kinds of perfumes. Perfumed leather for gloves, purses, etc., was at
that time imported from Spain. This leather was very expensive and
fashionable, but on account of its penetrating odor its use for gloves
was finally abandoned.
In England perfumes were not in general use before the reign of
Queen Elizabeth, when they soon became fashionable. Elizabeth had
an especially finely developed sense of smell and nothing was more
repugnant to her than a disagreeable odor. She had a cloak of perfumed
Spanish leather, and even her shoes were perfumed. Perfumed gloves were
also fashionable. The city soon imitated the practices of the court,
and that an extravagant use was made of perfumeries and cosmetics is
plainly seen from the works of the authors of that time, as well as
from an act of Parliament passed in 1770. By the latter it is ordained
that any woman, no matter of what age or rank, be she maid or widow,
who deceives a man and inveigles him into matrimony by the use of
perfumeries, false hair, _Crépons d'Espagne_ (a paint), corsets, hooped
petticoats, shoes with high heels, and false hips, shall suffer the
penalty of the law for procuring, and the marriage shall be null and
void.
CHAPTER II.
THE PERFUME-MATERIALS FOR THE MANUFACTURE OF PERFUMERY.
Most of the perfume-materials employed by the perfumer are derived from
the vegetable kingdom; a few are of animal origin, whilst some are
artificially prepared.
Of animal substances only four are used, namely: _musk_, _castor_
or _castoreum_, _civet_, and _ambergris_; the separation of their
characteristic odoriferous substances has, however, not yet been
accomplished. The odor of plants is generally due to volatile
substances called _volatile_ or _essential oils_. Their occurrence is
not limited to special parts, they being found in the flower, seed,
wood, bast, bark, leaves, and root. However, in every plant the oil
occurs chiefly in certain organs, and it even happens that the oil
differs with the part of the plant whence it is derived. The odors
exist already formed in the living plant, or else are generated, as in
the instance of bitter almonds, by some reaction between the elements
which takes place during fermentation or distillation.
From the strength of the odor of a plant no conclusion can be drawn as
to the quantity of volatile oil present. If this were the case, the
hyacinth, for instance, would contain more oil than the coniferae,
whilst in fact it contains so little that it can be separated only
with the greatest difficulty. The odor does not depend on the quantity,
but on the quality of the oil; a plant may diffuse but little odor and
still contain much volatile oil. Of the various families of plants, the
_labiatae_, _umbelliferae_, and _coniferae_ are richest in volatile
oils.
In every climate plants diffuse odor, those growing in tropical
latitudes being more prolific in this respect than the plants of colder
regions, which, however, yield the most delicate perfume. Although
the East Indies, Ceylon, Peru, and Mexico afford some of the choicest
perfumes, Central Europe is the actual flower garden of the perfumer,
Grasse, Cannes, and Nice being the principal places for the production
of perfume-materials. Thanks to the geographical position of these
places, the cultivator, within a comparatively narrow space, has at his
disposal various climates suitable for the most perfect development
of the plants. The _Acacia Farnesiana_ grows on the seashore, without
having to fear frost, which in one night might destroy the entire crop,
while at the foot of the Alps, on Mount Esteral, the violet diffuses a
much sweeter odor than in the hotter regions, where the olive and the
tuberose reach perfect bloom. England asserts its superiority in oils
of lavender and peppermint. The volatile oils obtained from plants
cultivated in Mitcham and Hitchin command a considerably higher price
than those from other localities, this preference being justified only
by the delicacy of their perfume. Cannes is best suited for roses,
acacias, jasmine, and neroli, while in Nimes, thyme, rosemary, and
lavender are chiefly cultivated. Nice is celebrated for its violets,
while Sicily furnishes the lemon and orange, and Italy the iris and
bergamotte.
The odors exhaled by our own domestic plants have been but little
studied, but the southern as well as many northern districts of the
United States are well adapted for the cultivation of quite a number
of species of plants which might be made to yield highly valuable
articles of commerce. Among the plants which might furnish oils for the
perfumer's use are, for instance, the wall flower, the Lilly, lilac and
mignonette.
VOLATILE OILS.--The volatile oils are either fluid (actual volatile
oils) or solid (varieties of camphor) or solutions of solid
combinations in fluid. The latter, on exposure to low temperatures,
separate into two portions, one solid, called _stearoptene_, and the
other liquid, called _elæoptene_. The boiling point of the volatile
oils is considerably higher than that of water, but when heated with
water they pass over with the vapors. Upon paper, fluid volatile oils
produce grease spots, which differ, however, from those caused by fat
oils in that they gradually disappear at an ordinary temperature,
and rapidly by gentle heating. Most volatile oils are insoluble, or
only with difficulty and sparingly soluble, in water, but they impart
to the latter their odor and taste. They are readily soluble in
alcohol, ether, chloroform, bisulphide of carbon and petroleum-ether,
and miscible in every proportion with fats and fat oils. By their
solubility in alcohol they differ from most fat oils. When freshly
prepared many volatile oils are colorless, but soon turn yellow;
some, however, show a distinct color even when fresh. They ignite
with greater ease than fat oils and burn with a fierce smoky flame
depositing a large amount of carbon. They exhibit a great tendency to
absorb oxygen from the air and to gum, the influence of light promoting
the process. In specific gravity they range from about 0.75 to 1.17,
most of them being specifically lighter than water. Most bodies, under
otherwise equal conditions, show always exactly the same specific
gravity, the variations being so slight that they may be justly
ascribed to errors of observation. However, one and the same volatile
oil frequently shows such variations in specific gravity, that we are
forced to ascribe this phenomenon to alterations in the constitution
of the oil itself. For the exact determination of the specific gravity
of a volatile oil, it should, therefore, be subjected to examination
immediately after its preparation from the plant or vegetable
substance, which should be as fresh as possible. The influence of
light upon volatile oils is best shown by the following interesting
experiment: If certain volatile oils are distilled in a vacuum or over
burnt lime in a current of carbonic acid, it is no longer possible
to distinguish, for instance, oil of lemon from oil of turpentine;
however, by again exposing the oils to the air, they reacquire their
characteristic odor.
According to their elementary composition the volatile oils may be
divided into three principal divisions:--
1. Volatile oils free from oxygen, terpene (camphene), or hydrocarbons.
2. Oxygenated volatile oils.
3. Volatile oils containing sulphur.
On account of the facility with which most of the volatile oils absorb
oxygen, oils originally free from oxygen are frequently a mixture of
hydrocarbons and combinations containing oxygen. The volatile oils
varying so much in their physical as well as their chemical properties,
a suitable classification of them has thus far been unsuccessful.
Most of the volatile oils contain a liquid hydrocarbon, _terpene_,
which is characterized neither by special taste nor odor, nor is
the peculiarity of a volatile oil dependent on it. In the direct
distillation of a volatile oil, for instance, lemon oil, this
hydrocarbon (citrene), passes first over and can, therefore, be readily
separated from the constituents on which depend the peculiarity
of lemon oil, and which distil over at a higher temperature. The
specific character of an oil is generally due to the portion of the
oil containing oxygen. Hence, manufacturers have endeavored to free
several of the volatile oils, used for perfumery and the preparation of
food, from the worthless terpene and at the same time to obtain them
in a concentrated form. Carvol is, for instance, caraway oil freed
from carvene (terpene). These concentrated oils are not only purer and
more agreeable in odor and taste and more readily soluble in dilute
alcohol, but, being more concentrated, an equal volume of them goes
much further than ordinary volatile oil. In the price lists these oils
are designated as _extra strong_, _patented_, _concentrated_, _highly
concentrated oils_ or _essences_.
All the terpenes occurring in the various oils are combinations
having the formula C_{10}H_{16}, or polymeric with it, C_{15}H_{24},
C_{20}H_{32}, etc. These terpenes exhibiting certain deviations in
regard to their properties, odor, specific gravity, and boiling
points, nearly as many terpenes as there are volatile oils have been
distinguished. It is, however, very likely that these deviations
may be traced back to fortuitous circumstances, for example, to
the admixture of foreign substances occurring together with the
terpenes, and that, by a more accurate examination, the number of
terpenes entitled to be considered pure chemical combinations will be
considerably reduced. By Wallach's labors, the identity of several
terpenes formerly considered distinct, has already been established,
whilst many others have been found to possess properties in common.
According to the nature and quantity of the odoriferous substances
contained in the plants, various methods, namely, _expression_,
_distillation_, _extraction_, _maceration_, and _absorption_, are
employed for the purpose of obtaining them.
_Expression._--This is only practicable when the substances are
especially rich in oil and of sufficient softness, as in the case with
the peel of the orange, citron, lemon, etc. In such instances the
material is simply placed in a linen cloth and subjected to a strong
pressure until it ceases to yield oil. The press may be of any size
according to the quantity to be expressed. For small quantities it
generally consists of an iron vessel, having a small opening at the
bottom so that the oil may flow out. The material is placed upon a
perforated bottom inside of the vessel and covered with a well-fitting
iron plate, that can be pressed down by means of a screw. Though the
material is fairly exhausted by such a press, for large operations it
is advisable to make use of a hydraulic press, which is constructed and
managed in exactly the same manner as those used for the expression of
fixed oils.
By expression a turbid milky fluid is obtained, which consists of
the volatile oil and aqueous substances. The latter are a solution of
various extractive substances and salts in water. This fluid, as it
runs from the press, is received in tall, narrow, glass vessels and
brought into a cool place for clarification. This frequently requires
several days, three distinct layers being generally distinguished. On
the bottom is a mucous layer consisting of cell substances carried
along by the liquid bodies. Over this is a clear fluid consisting
of a solution of extractive substances, vegetable albumen, and
salts, and upon this floats the volatile oil, being specifically the
lightest body, which, by its greater refractive power, can be clearly
distinguished from the aqueous fluid.
The oil is separated by bringing all that has been expressed into a
bottle provided near the bottom with a lateral neck closed by a cock.
After separating the oil from the aqueous fluid, the latter is allowed
to escape by opening the cock.
The oil obtained in this manner is still impure, and requires further
treatment to remove small vegetable fibres, invisible to the naked eye,
which float in them, and cause them to be somewhat opaque and slightly
opalescent. By their subsequent decomposition they would also give the
oil a disagreeable odor.
There are two methods of obtaining the oil entirely clear, viz.,
filtration and distillation. Filtration is the cheaper process, but
requires special precautions to exclude the air as much as possible to
prevent the oil from undergoing injurious changes. By arranging the
filtering apparatus so that the oil always comes in contact with only
the same quantity of air, the injurious action of the oxygen is reduced
to a minimum. It is self-evident that the apparatus should not be
placed in the sun, but in a semi-dark, cool place.
[Illustration: FIG. 1.]
A filter of simple construction, and performing excellent service, is
shown in Fig. 1. It consists of a large glass bottle, _F_, hermetically
closed by a doubly-perforated cork. The neck of the glass funnel _T_,
the upper rim of which is ground smooth, is placed in one of the holes,
and a glass tube, _r_, bent at a right angle, is fitted into the second
hole. A thick wooden lid, with a rubber ring on the lower side, is
placed upon the funnel, thus closing it air-tight. In the centre of the
lid is fitted a glass tube, _r´_, also bent at a right angle, which is
connected with the tube _r_, by a rubber hose, _k_. After the funnel
has been provided with filtering paper and the oil to be filtered, the
lid is placed upon it, and must not be removed, except for the purpose
of pouring more oil into the funnel. The air in the bottle _F_ is
displaced by the oil dropping into it, and escapes through _r_, _k_ and
_r´_ into the funnel, and thus only the air in the bottle and funnel
can act upon the oil.
The other method for the complete purification of expressed oil is
by rectification or distillation with water. For this purpose the
oil, together with a little water, is brought into one of the stills
described later on, and the oil distilled over. It is sometimes
difficult to obtain the last portion of the oil, especially with a
still heated by direct fire, and it is therefore preferable to combine
it with a fresh quantity of the same oil to be distilled.
_Distillation._--There are at present two methods in use. The one is
founded upon the direct action of the heat, the other upon the use
of steam. The first was formerly in general practice, and is still
largely employed in France and England, and to a limited extent in
this country. It is, however, very deficient in many respects. As the
stills must necessarily be of small capacity, only small quantities
can be distilled at one time, and the oils very rarely possess the
peculiar odor due to them, and sometimes the odor is even altered.
In mixing too little water with the materials to be extracted, there
is danger that empyreumatic oils will be formed; a large quantity of
water, on the other hand, is of disadvantage, in so far as in case
the perfume-materials contain little oil, only a perfumed water, but
no oil, will be obtained. In order to avoid these inconveniences, or,
at least, to do away with some of them, another plan was devised. The
materials to be distilled were spread upon sieves, which were suspended
in the upper part of a still, so that they might be penetrated from
below. It is true no scorching is possible in this case, as was in the
other process when the heating was continued after all the water had
evaporated, and the oil retains its proper color, but by this method
only small quantities can be extracted at a time. The still generally
used for distillation with direct heat resembles so much an ordinary
whiskey still as to need no further description here.
[Illustration: FIG. 2.]
For the accurate determination of the percentage of volatile oil a
vegetable substance will yield, or to obtain the oil from very costly
raw materials, the small glass apparatus, Fig. 2, is used. The flask
_A_, with a capacity of up to 5 or 6 quarts, serves for a still. In
the tube _t_, shaped like the neck of a bottle, is inserted by means
of a cork, a funnel tube, _l_, reaching to the bottom of the flask.
The neck of the flask passes into the cooling pipe, which lies in a
so-called Liebig cooler. This consists of a wide-glass tube, _C_, into
the lower end of which, at _h_, flows cold water from the reservoir
_D_, displacing the heated water at _g_. The lower end of the cooling
pipe is connected with the neck-shaped tube _v_, under which stands the
vessel for the reception of the distillate. To prevent the cracking of
the flask, which might readily happen with the use of direct heat, it
is placed in a vessel filled with sand or water.
[Illustration: FIG. 3.]
A very good small apparatus for the distillation of volatile oil is
shown in Fig. 3. It is known as a siphon still. It consists of a
double-walled boiler, surmounted by a still-head, which is provided
with a mechanism for keeping the contents of the boiler in motion. This
stirring apparatus consists of a perpendicular shaft, bearing a frame
work of iron, curved so as to correspond to the interior shape of the
still, and on the outside carrying a chain which scrapes over the inner
surface of the still while the stirrer is being turned. This may be
done either by hand or by steam. The still having been charged with
the material to be extracted, is filled up with water to within a few
inches of the top of the body of the still, and the latter is heated by
admitting steam. The vapors arising are conducted to a cooler situated
at a higher level than the still itself, and the condensed liquid
is collected in a receiver, where the oil and water separate. This
receiver is provided with two faucets, one near the top and the other
near the bottom. If the oil passing over is heavier than water, the
excess of the latter is removed by the upper faucet; if the oil swims
on the water, the lower faucet is regulated so as to allow the water
to escape in about the same ratio as it enters the receiver. In either
case the condensed water is made to run back into the still, and the
loss of oil is, therefore, greatly reduced.
Sometimes a single-walled still is used, and distillation carried on
with direct steam. This method is, however, not suitable where the
presence of water is necessary, for instance, in the production of oil
of bitter almonds.
A simple way of converting an ordinary still into use with steam is
shown in Fig. 4. For the helmet of the still _A_ is substituted a
cylindrical vessel, _B_, with an opening in the bottom. The materials
to be distilled are brought into _B_, and rest upon a wire bottom
to prevent particles from falling into _A_. From the upper portion
of _B_ a pipe, _R_, leads to the condenser. As may be seen from the
illustration, the still _A_ serves only for the generation of steam.
The latter, in passing through _B_, heats the contents and absorbs the
liberated oil, the combined vapors passing into the condenser.
[Illustration: FIG. 4.]
This simple modification of the ordinary still affords some advantage,
the principal being the avoidance of the condensation of a large
quantity of water. This in itself would not amount to much, but it has
to be taken into consideration that, though volatile oils are only very
sparingly soluble in water, they are nevertheless soluble in it to
such a degree as to impart to it their characteristic odor and taste.
Such aromatized water can be utilized in the manufacture of liqueurs
and perfumery, but to the manufacturer who restricts himself to the
production of volatile oils alone, this represents a loss, and it is
therefore necessary for him to condense as little water as possible.
And this object can only be attained by the use of direct steam.
A simple apparatus for the purpose is shown in Fig. 5. The still _b_,
provided with a helmet, rests free upon a suitable support. To prevent
cooling, it is surrounded with a wooden jacket, _M_. The material to be
extracted rests upon a perforated bottom, beneath which enters the pipe
_HD_, which conducts the steam from the boiler. For the more uniform
distribution of the steam, it is recommended to let this pipe end in
a perforated coil. The water condensed in the apparatus itself is
discharged through the short pipe _H_, placed in the lowest part of the
still.
[Illustration: FIG. 5.]
An improved apparatus for distilling dry substances by steam has
been patented in Germany by Messrs. Schimmel & Co., of Leipzic. The
tall conical column at the left (Fig. 6) is the still. About eight
inches from the bottom is a perforated diaphragm or false bottom,
upon which the material to be distilled is placed by introducing it
through the still-head. A perforated coil below the diaphragm projects
steam upwards through the mass, which is occasionally agitated from
without by means of a horizontal stirring apparatus indicated by the
two crosses. Any condensed water which may run back is converted into
steam by the heating coil at the bottom. Meanwhile, the mass itself is
heated by a long coil lining the body of the still and carrying steam
at a high pressure. Whatever of volatile oil is carried forward by the
steam passes through the still-head into the cooler on the right, where
both oil and steam are condensed, and from where they flow through a
small funnel tube into three successive receivers, which are arranged
like Florentine flasks, and which retain the volatile oil that has
separated. From the last receiver the water, which is still impregnated
with oil, enters another reservoir, shown in the illustration only by
dots, and from there it flows into a small globular still situated
underneath; in which, by means of steam, nearly all the oil still
retained is again volatilized with the steam of the water and both
again conducted to the cooler.
[Illustration: FIG. 6.]
Attempts have been made to effect the distillation of volatile
oils without the use of steam by means of hot air, but comparative
experiments have shown that less oil is obtained. With the use of
steam, the vegetable substances swell up by the absorption of water,
and thus afford a free passage to the oil, liberated from the sacs
containing it. With the use of hot air, on the other hand, the surface
of the plant is completely dried and shrivels to a hard solid mass,
which offers considerable resistance to the process of distillation.
This injurious effect of hot air can be somewhat overcome by thoroughly
moistening the plants to be distilled, and allowing the hot air,
before entering the still, to pass through a pipe filled with sponges
constantly kept wet. But this process offers no advantages over that by
steam. The apparatus required is far more complicated; and, besides,
a ventilator has to be provided for forcing the hot air through the
apparatus.
_Separation of the oil and water._--As previously mentioned the
specific gravity of most volatile oils is less than that of water. This
behavior is utilized for the separation of the oil and water, by means
of a so-called Florentine flask (Fig. 7). It consists of a glass flask
provided near the bottom with a pipe, _a_, rising vertically to near
the neck _c_ of the flask where it is bent downwards as shown in the
illustration. The mixed liquid of water and oil drips from the cooling
pipe into the flask, and the water _w_, being specifically heavier,
separates from the oil floating on the top, and gradually ascends in
the pipe _a_, finally flowing over at _d_. Oils specifically heavier
than water are caught in receivers provided with a discharge-pipe near
the mouth of the flask as shown in Fig. 8.
[Illustration: FIG. 7.]
[Illustration: FIG. 8.]
The oil delivered from the receivers is, however, still mixed with
some water, dirt, etc., and for their separation is allowed to stand
quietly for some time. The final separation is effected either by
simply pouring off the oil, especially if larger quantities have to be
handled, or with the assistance of a separator-funnel (Fig. 9). This
consists of the glass-funnel _T_ secured to the stand _G_, and provided
with a close-fitting lid, _P_. The fluid is poured into the funnel, the
lid placed in position, and the whole allowed to rest until the water
_W_ is completely separated from the oil _O_. The oil is then separated
from the last drops of water by carefully opening the faucet _H_.
Most volatile oils are obtained by distillation, but this method is
not practicable for separating the odoriferous principle of many of the
most sweet-scented and delicate flowers, partially because the flowers
contain too little oil, and partially because the oil would lose in
quality if obtained by distillation.
[Illustration: FIG. 9.]
_Extraction._--For obtaining the volatile oils by extraction various
solvents such as ether, bisulphide of carbon, etc., may be employed.
Carefully rectified petroleum-ether is very suitable for the purpose.
It completely evaporates at about 122° F., and when sufficiently
purified does not possess a disagreeable odor. The process of
extraction is briefly as follows: The material to be extracted is
treated in a digester with petroleum-ether or one of the above-named
solvents. The solution is then drawn off and the solvent evaporated
in a still. The recondensed solvent flows immediately back into the
digester and further extracts the material contained therein. The
operation is repeated until nothing soluble remains. In practice some
difficulties are, however, connected with this process since, besides
the volatile oils, resins, and coloring and extractive substances are
dissolved, which have to be removed, as well as the last traces of the
solvent, as otherwise the oil would acquire a foreign odor. Further
the solvents mentioned are very volatile and inflammable, requiring
the greatest precautions as regards fire. For these reasons the
extraction process is not suitable for many purposes, and though at
first great hopes were entertained in regard to it, its use is limited
to substances with a large content of volatile oil.
[Illustration: FIG. 10.]
For extraction on a small scale, the apparatus, Fig. 10, is a very
suitable one. It is especially adapted for manufacturers of perfumery,
who wish to extract fresh flowers. It consists of a cylindrical vessel,
_C_, of tin plate, provided on the bottom with the stop-cock _a_ and
the pipe _b_. The lid _D_ fits into a gutter, _R_, running around the
edge of _C_, and is hermetically closed by water in _R_. The cylinder
is filled with the vegetable substance to be extracted, and sufficient
petroleum-ether or bisulphide of carbon to cover it, poured in. The lid
is then adjusted, the gutter _R_ filled with water and the apparatus
allowed to stand quietly for forty minutes. To remove the fluid from
the cylinder, the faucet _o_ in the lid is first opened, and then the
stop-cock _a_; the fluid escapes at _b_, and is caught in a well-closed
vessel. The operation may be repeated once or twice, or the vegetable
substance is pressed out by means of a wooden plate, and the apparatus
filled anew. The faucet _h_ serves for emptying the gutter _R_.
[Illustration: FIG. 11.]
Extraction being finished, the cock _o_ is opened, and then the cock
_a_, and the fluid allowed to run into the flask of the distilling
apparatus (Fig. 2). For working on a large scale, the flask is,
however, too small, and is suitably replaced by a bottle-shaped tin
vessel, _F_ (Fig. 11), the conical cover _D_ of which is secured by
means of the rubber ring _R_ and iron screw-clamps, _S_. A bent glass
tube fitted into the cover is connected with the cooling-pipe of the
apparatus shown in Fig. 2. But the oils prepared by extraction are not
sufficiently purified by mere rectification, as traces of the solvent
adhere tenaciously to them, which can only be removed by passing a
current of air through the oil. But contact with air has an injurious
effect upon the delicacy of the odor. For expensive oils a current of
air should therefore never be used, but one of pure carbonic acid.
Fig. 12 shows a suitable apparatus for the purpose. The large bottle
_A_, filled half full with pieces of white marble, is closed with
a doubly-perforated cork; through one of the holes is inserted a
funnel-tube, and through the other a short tube bent at a right angle.
The latter is connected with another tube which reaches to the bottom
of the vessel _B_, in which is also inserted a tube open in the bottom,
and a short tube bent at a right angle. Alongside _B_ stands another
vessel, _C_, arranged in the same manner. The tube leading from _C_ is
connected with a tin pipe, _D_, with a rose-like expansion on its lower
end. This pipe is inserted in the glass balloon containing the volatile
oil. Finally, a pipe leads to the flask _F_, filled with water.
[Illustration: FIG. 12.]
To put the apparatus in operation, strongly diluted hydrochloric acid
is poured through the funnel-tube upon the pieces of marble in _A_,
which causes the development of a current of carbonic acid. But as the
latter carries along water and hydrochloric acid, it has to be freed
from them before coming in contact with the volatile oil. The vessels
_B_ and _C_ serve for the purpose. _B_ is half filled with water,
while _C_ contains strong sulphuric acid. In _B_ the hydrochloric acid
carried along with the current of carbonic acid is retained, while the
water is fixed on the sulphuric acid in _C_. The current of carbonic
acid passing out from _C_ is perfectly pure, and enters the volatile
oil through the fine perforations in the pipe _D_. It absorbs the
traces of solvent still adhering to the oil, and finally passes out
through the water in the bottle _F_.
Volatile oils obtained by extraction, and purified by a current of
carbonic acid, will keep for years without undergoing alteration, if
placed immediately in hermetically closed vessels and stored in a dark
place. Oils purified by a current of air always become somewhat thickly
fluid by storing, and partially lose their fine odor, which is due to
the oxygen absorbed during the process.
For the extraction of oil on a larger scale, the apparatus shown in
Fig. 13 is very suitable. It consists of two principal parts, the
actual extracting vessel _E_, and the still _B_. The extracting vessel
_E_ sits in a vat containing cold water, _W_, the arrangement being
such that the heated water can be removed and replaced by cold. The
still _B_ sits in a boiler, _K_, filled with hot water.
The apparatus is charged as follows: The conical head _C_ of the
extracting vessel _E_ is unscrewed and its connection at _H_ with the
pipe _R_ loosened. The extracting vessel is then charged with the
vegetable substance, the head _C_ replaced, and the connection with the
pipe _R_ restored. The cocks _H_{2} and _H_{4} are then opened, and
the required quantity of solvent is brought into the still. Both cocks
are then closed, and the cocks _H_ and _H_{1} opened. The water in the
boiler is then heated until the contents of the still commence to boil.
The vapor of the solvent ascends through the pipe _R_; on entering the
extracting vessel _E_ it is condensed, and after falling as a spray
upon the material to be extracted, finally returns impregnated with
volatile oil to the still _B_. Here the solvent is revaporized, and
passes again through the material in the extracting vessel, while the
extracted oil remains in the still. During the boiling of the solvent
the extracting vessel must be suitably cooled by the constant admission
of cold water.
[Illustration: FIG. 13.]
When extraction is finished, the cocks _H_ and _H_{1} are closed, and
the cock _H_{2}, which is connected with a cooling worm, is opened.
The solvent is then evaporated, and regained by condensation. The oil
is discharged, from the still through a pipe in the bottom provided
with the cock _H_{3}.
The apparatus may also be so arranged that the still _B_ is connected
with two extracting vessels which are used alternately, while the
contents of one are being extracted the other is emptied and refilled.
[Illustration: FIG. 14.]
For working on a very large scale, Heyl's extracting apparatus, shown
in Fig. 14, is very suitable. It consists of a battery of four or more
cast iron or sheet iron cylinders, _A_{1} to _A_{4}, communicating
with each other and surrounded by steam jackets. The extracting
vessels are so arranged that they can be emptied by tilting, which is
rather inconvenient, as all the pipes have to be unscrewed. In each
cylinder close above the bottom is a perforated plate covered with
fine wire-gauze, upon which the material to be extracted is placed.
The cylinder is filled to the top, and, after placing a similar plate
upon it, the upper opening is closed by a lid suspended to a crane. The
cylinder, as well as the lid, is provided with a broad flange, between
which is placed a hemp tissue firmly pressed together by 12 clamps to
serve for packing. After filling the cylinders with the material to be
extracted and arranging the packing, the solvent (bisulphide of carbon)
is conducted from a reservoir through the principal pipe, _B_, to the
extracting vessels, and is introduced into _A_{2} by opening the cock
_C_{2}, which communicates with the pipe _B_. The bisulphide of carbon
passes through the bent pipe _D_{1}, enters through the cock _E_{2},
below the false bottom of the cylinder _A_{2}, and, after penetrating
the mass and filling the cylinder, runs through the cock _C_{2} of
the bent pipe _D_{2}, and the cock _E_{3} into the cylinder _A_{3},
reaching the fourth cylinder in the same manner through the cock
_C_{3}, the pipe _D_{3}, and the cock _E_{4}. From the last cylinder
it passes as a thoroughly saturated oil solution into a reservoir, in
which a vacuum has been created to promote the circulation of the fluid
in the entire apparatus. After a quantity of oil solution corresponding
to the contents of the cylinder _A_{4} has arrived, the cock _G_{4}
is closed and the cock _C_{4} opened, whereby the cylinder _A_{4} is
connected with _A_{1} by the bent pipe _D_{4} and the cock _E_{1}.
After the exhaustion of the contents of the cylinder _A_{2}, which
is recognized by means of the glass tube _H_{2} placed on _D_{2} by
the fluid running off being colorless, the cocks _C_{1} and _E_{2}
are closed, and _C_{2} and _E_{3} opened, whereby the solvent runs
into _A_{3}, and from there to _A_{4} and _A_{1}; _A_{2} being
omitted. To effect this omission, and at the same time not to prevent
the introduction of bisulphide of carbon, _C_{1}, _C_{2}, _C_{3},
and _C_{4}, are so-called two-way cocks, which, when placed in one
position, connect the principal pipe _B_ with the branch pipes _D_, but
interrupt a further flow through the principal pipe _B_; while in the
other position they close the pipes _D_ and open the principal pipe _B_.
The cylinder _A_{2} is, however, still filled with the solvent and
material saturated with it. To remove the solvent, the discharge cock
_K_{2} on the bottom of the cylinder is opened, which communicates
with the discharge pipe _J_, through which the bisulphide of carbon
is conducted into a reservoir. The discharge is promoted by opening
the cock _M_{2}, connected with the pipe _L_, and the admittance of
compressed air, which displaces the liquid solvent. After the flow
of the latter has ceased, the steam cocks on the jacket _O_{2} and
the cylinder _P_{2} are opened under constant admission of air and
simultaneous introduction of steam through the pipe _N_ into the upper
part of the cylinder.
The solvent (bisulphide of carbon) converted into vapor by the heat,
is conducted together with the aqueous vapor, by the admission of air
through the cock _K_{2}, the pipe _J_, and a cooling pipe placed
between the extracting vessels and the reservoir, and collected in a
reservoir to be re-used.
On account of the great volatility of bisulphide of carbon,
considerable loss would, however, be incurred by the above-mentioned
admission of air. To avoid this, the reservoir serving for the
reception of the condensed bisulphide of carbon and aqueous vapor
is closed, and connected by a pipe with a long, narrow, horizontal
cylinder half filled with oil, and provided with a fan-shaft. The
vapors of bisulphide of carbon entering the cylinder from the reservoir
are absorbed, together with the air by the oil, the surface of which is
constantly agitated by the fan-shaft, while the air, rendered entirely
inodorous, passes out at the other end. The bisulphide of carbon is
finally separated from the oil by distillation and again used.
After the cylinder _A_{2} is sufficiently steamed, it is emptied and
again charged with material and connected with the cylinder _A_{1};
while the other cylinders undergo the same manipulations described
above.
[Illustration: FIG. 15.]
The saturated oil solution is subjected to distillation, which is
readily effected in Heyl's apparatus, Fig. 15. The lower part of the
still _A_ of boiler plate is surrounded by the steam-jacket _B_, into
which steam is admitted through _C_ and the condensed water discharged
through _D_. The concentrated oil solution runs from a reservoir,
standing at a higher level through the pipe _E_ into the still, the
admission of a sufficient quantity being indicated by the gauge _F_.
The bisulphide of carbon brought to the boiling point (114° F.) by the
steam introduced into the jacket, vaporizes quickly; the vaporization
being still more accelerated by revolving the stirrer _H_, by means of
the crank _G_. The vapors of bisulphide of carbon escape through four
openings in the upper part of the still, into a capacious worm, the
lower part of which enters, under water, a reservoir.
Notwithstanding the volatility of bisulphide of carbon, the oil retains
a portion of it so tenaciously that a complete separation cannot
be accomplished by the introduction of steam into the jacket _B_.
Hence, in order to vaporize the last traces of the solvent, air is
introduced into the oil through the pipe _K_, the lower end of which is
perforated. After completed distillation the oil is discharged through
_L_.
_Maceration or infusion._--This process is employed for flowers with an
inconsiderable content of volatile oil or whose odoriferous substance
would suffer decomposition or alteration by distillation. The process
is founded on the affinity of odoriferous substances for fatty bodies
which, when impregnated with them, are called _pomades_. These are
afterwards made to yield the aroma to strong alcohol, so that finally
there is obtained a solution of the volatile oil in alcohol from which
the pure oil is obtained by distilling off the alcohol. The fat used,
olive oil, lard, etc., should be entirely neutral, _i. e._, free from
every trace of acid. The fats are purified by treating them several
times in the heat with weak soda-lye and then washing carefully with
water until the last traces of the lye are removed, and the fat shows
no alkaline or acid reaction.
With the use of olive oil the so-called "_Huiles antiques_" are
obtained, which are merely solutions of volatile oils in the fixed oil.
By the use of lard, etc., the genuine _pomades_ are obtained, which are
directly used as expensive articles of perfumery, but in the factories
serve as a starting point for the preparation of volatile oils.
The old process of maceration, which is still in use in some parts
of France, is as follows: A certain quantity of fat is placed in an
enameled iron or porcelain pan provided with a water or steam bath.
When the fat is melted, the freshly gathered flowers from which the
aroma is to be extracted are thrown in and left to digest for from
twelve to twenty-four hours, the fat being kept fluid and stirred
frequently. When the flowers are completely exhausted, the fat is
strained from them into fresh pots, in which it is again macerated with
fresh flowers as before. This operation is repeated ten to fifteen
times until the pomade has acquired the desired strength.
Experience, however, has shown that volatile oils prepared by this
process possess a finer odor the shorter the time the flowers remain
in contact with the fat. Piver has devised an apparatus which reduces
the time of maceration to the shortest period possible. The kettle to
the left, Fig. 16, supplies the fat heated to the proper temperature,
which circulates slowly through the macerating tank, in which a
constant temperature of 149° F. is maintained by means of a steam pipe.
The macerating tank is divided into compartments, in which baskets
containing the vegetable substance to be extracted are suspended. The
basket on the left contains the substance which has passed through
all the compartments; it is from time to time removed, filled with
fresh substance, and then attached to the right, the other baskets
being moved to the next compartment to the left. In this way the fresh
substance has to traverse each compartment from right to left, while
the fat flows slowly from left to right, and saturated with the perfume
of the substance collects in the tank on the extreme right.
[Illustration: FIG. 16.]
Maceration is employed for the flowers of the orange (_citrus
aurantum_), of the mock orange (_Philadelphus coronarius_), of the
acacia (_acacia Farnesiana_), of the violet (_viola odorata_), of the
mignonette (_réséda odorata_), etc.
The process of _absorption_, or "_enfleurage_," as it is called by the
French, is chiefly made use of for procuring the odoriferous principle
of very delicate flowers, the delicious odor of which would be greatly
modified, if not entirely spoiled, by the application of heat. The
older apparatus employed for the purpose consists of a number of
shallow wooden frames of about 15×18 inches, inclosing at half their
depth a sheet of glass. The edges of the frame rise about an inch above
each surface of the glass, and, being flat, the frames stand securely
upon one another, forming often considerable stacks. These frames
are called "_chassis_," those just described being termed "_chassis
aux vitres_," or "_chassis aux pomades_," to distinguish them from a
different form, which is used where oil has to be submitted to the
process of absorption. The process in the case of pomade is as follows:
Each sheet of glass is uniformly coated with a thin layer of purified
grease, care being taken that the grease does not come in contact with
the woodwork of the frames. The flowers are then thinly sprinkled, or
rather laid, one by one, upon the surface of the fat, where they are
allowed to remain one or two days, when they are removed and replaced
by fresh ones. The operation is thus continued for twenty-five or
thirty days, until the fat is saturated with aroma. The frames charged
with fat and flowers are stacked one upon the other, forming, in fact,
a number of little rectangular chambers.
For _perfuming oils_ a metal sieve, Fig. 17, is substituted for the
glass plate. Upon the sieve a piece of thick cotton cloth saturated
with oil is laid, and upon this the flowers are scattered, and left
there until fresh ones have to be substituted. The operation is
repeated until the oil is sufficiently impregnated with aroma, when
the cloth is subjected to pressure and the expressed oil filtered.
[Illustration: FIG. 17.]
This process is very tedious, requiring much labor and a long time for
the impregnation of the fat or oil, but, notwithstanding its faults, it
is still pursued to a great extent, some French firms using 3000 such
frames during the season.
With the apparatus, shown in Fig. 18, the process of absorption can,
however, be conducted with very little expense of labor and time.
It has the further advantage that the flowers do not come in direct
contact with the fat, whereby a saving of the latter is effected, and
it is less liable to rancidity.
The apparatus consists of a tall wooden box provided with doors which
can be hermetically closed. In the box are placed upon brackets a
number of glass plates, _g_, so arranged one above the other that, for
instance, those with uneven numbers are on the left side, leaving an
open space to the right, while those with even numbers are arranged on
the right side with an open space to the left.
From the bottom of the box a pipe passes into a sheet-iron cylinder,
_K´_, filled loosely with flowers, and provided with lateral openings,
_O_ and _O´_. From the lid of the box _K_ ascends a pipe, _e_, which
is connected with a small ventilating apparatus kept in motion by a
clockwork and weights. This ventilator when in motion sucks a current
of air through the apparatus. The air enters the cylinder _K´_ at _O_,
and after ascending through the flowers and becoming impregnated with
the vapors of the volatile oil enters through the opening _O´_ into the
box _K_ and, in passing in the direction indicated by arrows, over the
plates coated with fat, yields its aroma to them.
[Illustration: FIG. 18.]
Another apparatus for the same purpose, devised by Piver, is shown
in Fig. 19. The fat is converted into thin macaroni-like threads
and brought upon wire gauze stretched in frames. The flowers to
be extracted are piled upon tinned metallic plates, and the trays
containing the fat and the flowers are placed in an air-tight chamber
arranged as shown in the illustration. The air in the chamber is made
to circulate to and fro by the working of a bellows with which the
apparatus is provided, whereby the fat is caused to absorb the odor of
the flowers very rapidly and is less liable to rancidity.
[Illustration: FIG. 19.]
The absorption process is employed for the flowers of the jasmine
(_jasminum oderatissimum_), the mignonnette (_réséda odorata_), the
violet (_viola tricolor_), the tuberose (_polianthes tuberosa_), etc.
_Storage of volatile oils._--In storing volatile oils, they should
be carefully protected from light and air. Some oils become darker
on exposure to light, while others, for instance, lemon oil, become
colorless. Most volatile oils, as previously mentioned, absorb oxygen
from the air with avidity and combine chemically with it. Thinly-fluid
oils become perceptibly more thickly-fluid and finally even rigid,
the product of oxidation being a resinous body. Some volatile oils
containing aldehydes are converted, by the absorption of oxygen, into
acids, cinnamic acid being, for instance, formed in cinnamon oil, and
benzoic acid in oil of bitter almonds.
To prevent evaporation, as well as the above-mentioned effects of
light and air, the volatile oils should be preserved in not too large
glass bottles kept as full as possible, and closed with a good cork,
over which it is best to tie a piece of bladder. The bottles should be
stored in a cool, shady place. The preservation of the oils is assisted
by the addition of 0.5 to 1 per cent. of anhydrous alcohol.
CHAPTER III.
TESTING VOLATILE OILS.
Volatile oils are much adulterated, the adulterations consisting
chiefly in mixing an expensive oil with a cheaper one and with alcohol;
more rarely with chloroform and fat oils. To these adulterations, which
have been common for many years, has recently been added the previously
mentioned hydrocarbon called terpene or camphene, which is separated in
the preparation of concentrated oils.
For the recognition of the quality of a volatile oil, serve first of
all its physical properties, especially its color, odor and taste.
The specific gravity varies too much and is not always a sufficient
criterion. Reagents can only be employed with a few oils. The chemical
detection of adulterations is rendered especially difficult by the
fact, that most of the volatile oils form a mixture of terpenes with
other combinations, in which the separate constituent parts do not
appear in fixed, but in changeable proportions, and in which the
constituents themselves suffer alteration by storing, air and light.
_Odor and taste_ are so characteristic for every volatile oil as to
suffice in most cases. For testing as to odor, bring a drop of the oil
to be examined upon the dry palm of one hand and for some time rub
with the other, whereby the odor is more perceptibly brought out. To
determine the taste, vigorously shake one drop of the oil with 15 to 20
grammes of distilled water and then test with the tongue.
An adulteration with _fat oil_ (poppy oil, castor oil) may be
recognized as follows: Place a drop of the suspected oil upon blotting
paper and expose it to the heat of the water bath. If it evaporates
completely and no stain is perceptible, the oil is pure. But frequently
a transparent stain remains with old oils without their being
adulterated, which is due to the resin formed by the absorption of
oxygen and remaining dissolved in the oil. In this case a transparent
ring is generally formed by the concentration of the resin on the
edges of the stain. If no tangible results are obtained by this test,
pour a few cubic centimeters of the oil upon a watch-crystal and
heat it very slowly upon a piece of sheet-iron, until all the odor
has disappeared. If the watch-crystal becomes empty in a short time,
nothing but volatile oil was present; but if a viscous residue remains,
this may consist either of fatty oil or resin, or of both. Treat the
residue with strong alcohol; if it dissolves it may be resin or castor
oil. Dilute the solution with much water; a white flocculent turbidity
indicates resin; the separation of an oily liquid, after standing,
castor oil. If the residue remains undissolved, it consists of a fatty
oil, generally oil of almond or olive.
The presence of castor oil can be accurately determined by bringing
the residue from the watch-crystal into a test-tube by means of a
glass-rod, and compounding it with a few drops of nitric acid. A
strong development of gas takes place, after the cessation of which,
solution of carbonate of soda is added as long as there is any sign
of effervescence. If the added oil was castor oil, the contents of the
test-tube will show a peculiar odor due to œnanthylic acid formed by
the action of nitric acid upon castor oil.
Another method of establishing the presence of fat oil consists in
mixing the suspected oil with eight times its quantity of 90 per
cent. alcohol (specific gravity 0.823). If the oil is unadulterated a
clear solution is formed; if it contains fat oil, the latter remains
undissolved. The presence of castor oil, which of the fat oils is
chiefly used for adulteration, is, however, not shown by this method,
it being also soluble in alcohol.
A permanent stain upon the paper may, however, also be formed by fresh
oils obtained by expression from the respective parts of the plant.
Thus, lemon oil obtained by expression from the peel, and which has
a far more agreeable odor than that produced by distillation, always
leaves behind a slight grease-stain.
_Detection of alcohol or spirit of wine._--Independent of the alcohol
added to assist the preservation of some oils, adulteration with
alcohol frequently occurs, especially in expensive oils. With a content
of not more than 3 per cent. of alcohol, it suffices to allow one to
two drops of the suspected oil to fall into water. In the presence of
alcohol, the drop becomes either immediately surrounded with a milky
zone, or it becomes turbid or whitish after being for some time in
contact with the water. Dragendorff's test is based upon the fact
that oils, which are hydrocarbons, suffer no change by the addition
of sodium (ten drops of oil and a small chip of sodium), while oils
containing hydrocarbons and oxygenated oils cause with sodium a slight
evolution of hydrogen gas, and suffer but a slight change during the
first five to ten minutes of the reaction. If, however, the oil is
adulterated with alcohol, not only a violent evolution of hydrogen gas
takes place, but the oil in a short time becomes brown or dark brown,
thickly fluid or rigid.
The detection of alcohol by means of fuchsine, which has been
frequently recommended, requires special precautions. It must first
be ascertained that the oil is free from acids and water; if such
is not the case, they must be removed by means of caustic potash.
After settling, bring, by means of a dry pipette, about five cubic
centimeters of the oil into a dry test-tube about ten millimeters
in diameter, without moistening the walls of the upper half of the
tube. Then bring, by means of a paper gutter, a few milligrammes of
coarsely-powdered fuchsine into the dry part of the obliquely held
tube, at a distance of one centimeter from the oil. Now heat gradually
over a lamp until the tube begins to tarnish. With pure oil no
evaporation is observed, but if the oil contains only 0.1 per cent.
of alcohol, every speck of fuchsine will, after heating to boiling
and setting aside, be surrounded by a stain produced by the alcoholic
solution. The chief requirement for this test is that the oil be free
from water. If such is not the case, vapors will be observed, which
condense in the upper portion of the test-tube, and dissolve fuchsine,
and, after flowing back, sink below the oil with a crackling noise. If
the oil contains alcohol, the condensing vapors dissolve fuchsine with
greater ease, and in flowing back mix without crackling.
Hager's tannin test is very reliable. Bring into a test-tube 5 to 10
drops of the oil to be examined, add a piece of tannin the size of a
pea, shake so that the tannin is moistened by the oil, and let the
whole stand at a temperature of 59° to 68° F. In most volatile oils
tannin is insoluble, and, if the oil is pure, floats for days on the
surface without change. If, however, the oil contains alcohol, the
tannin absorbs the latter, according to the quantity present, in 3 to
48 hours, and forms with it a more or less transparent, viscous, tough,
or smeary mass resembling a soft resin, which settles on the bottom,
and adheres so firmly to it, as well as to the sides of the tube, that
it cannot be moved by shaking. The mass may be examined as to its
consistency with a knitting needle. Traces of moisture in the oil are
not detrimental to the test, the tannin mass separating in the form of
a hyaline mass only in few oils, and if this mass is tested with the
knitting needle it will be found not tough or smeary, but hard, and may
sometimes be divided into small grains. With oil of bitter almonds,
cassia oil, and some oils of clove, as well as volatile oil containing
an acid, the tannin test is not available. The first two oils even
dissolve tannin, and large quantities of it, if they contain alcohol.
The above-mentioned oils may, however, be rendered fit for the
tannin test by mixing them with double their volume of benzine or
petroleum-ether, and allowing the mixture to stand for two or three
days. If, however, the oils contain much alcohol, the tannin is
dissolved. The use of powdered tannin is not advisable, because it
generally deposits in a thin layer on the bottom, and its alteration
is not so perceptible. If, for practical reasons, a content of 0.5 per
cent. anhydrous alcohol might be accepted as permissible in a volatile
oil, the tannin test would have to be so modified as to mix 10 drops
of the oil with a piece of tannin the size of two peas, and allow the
whole to stand for one hour. In this time the above-mentioned content
of alcohol would yield no result.
_Detection of chloroform._--An adulteration with chloroform, if
moderate, cannot always be detected by the odor and taste. In most
cases, chloroform will considerably increase the specific gravity of
the oil. Bring into a test-tube 15 drops of the suspected oil, 45 to 90
drops of alcohol, and 30 to 40 drops of dilute sulphuric acid. After
thorough shaking, add 2 or 3 shavings of zinc sheet and heat until a
vigorous evolution of hydrogen takes place. After again shaking, set
the whole aside, and heat again when the evolution of gas becomes
weaker. This heating and gentle shaking of the fluid is several times
repeated. After 20 to 25 minutes, compound the fluid with an equal
volume of cold distilled water, shake vigorously and filter through a
paper-filter moistened with water. Strongly acidulate the filtrate with
nitric acid and compound with nitrate of silver solution. If chloroform
is present, turbidity or a precipitate of chloride of silver appears.
_Detection of benzine._--An adulteration with benzine can be readily
detected only in oils specifically heavier than water. The separation
of benzine is effected by distillation from a small glass flask in the
water bath. The distillate together with an equal volume of nitric acid
of 1.5 specific gravity is gently heated in a test-tube. A too vigorous
reaction is modified by cooling in cold water, and a too sluggish
action quickened by gentle heating (dipping in warm water). If the
mixture has a yellow color, dilute it with water, shake with ether,
mix the decanted ethereal solution with alcohol and hydrochloric acid,
add some zinc and place the whole in a lukewarm place to convert the
nitrobenzol formed into aniline. After evolution of hydrogen is done,
neutralize with potash lye, shake, take off the layer of ether, let the
latter evaporate and add to the residue a few drops of calcium chloride
solution. If benzine is present, a blue-violet color reaction takes
place.
Adulterations with alcohol, chloroform, and benzine are quantitatively
determined by bringing a weighed quantity of the oil into a glass flask
so that it occupies about four-fifths of the volume of the flask. Place
upon the flask a cork through which has been passed a glass-tube bent
at a right angle and provided with a cylindrical glass vessel serving
as a receiver and heating in the water bath. If the distance from the
level of the oil to the angle of the glass tube in which it inclines
downwards, amounts, for instance, to 4.72 inches, and the neck of the
flask up to its angle is 2.75 inches high outside of the direct effect
of the heat of the water bath, only the above-mentioned adulterants
distill over, while the vapor of the volatile oil condenses at a
height of 2.75 inches and flows back into the flask. The distillate
is weighed and examined as to its derivation. First add one cubic
centimeter of it to two or three cubic centimeters of potassium acetate
solution of specific gravity 1.197 and shake moderately. If a clear
mixture results, alcohol alone is present. If, however, the mixture
is not clear, and the distilled fluid sinks down and collects on the
bottom of the test-tube, chloroform is very likely present, and if
it remains floating upon the acetate solution, benzine. Next bring
two to three centimeters of the distillate into a test-tube and add
a piece of sodium metal, the size of a pea. If violent foaming, _i.
e._, an evolution of gas, takes place, alcohol is certainly present,
and possibly also chloroform and benzine towards which sodium is
indifferent. However, in the presence of benzine, the sodium solution
would be colorless, and in the presence of chloroform, yellowish
and turbid. In case the sodium produces no reaction and alcohol is,
therefore, not present, add an equal volume (two to three cubic
centimeters) of anhydrous alcohol, and after moderately shaking allow
the solution of the sodium and the evolution of gas to proceed, whereby
benzine produces a nearly colorless, turbid fluid, and chloroform a
yellowish, milky one. Now dilute the fluid with an equal or double
volume of water, shake and allow the mixture to stand quietly. In the
presence of benzine a colorless, turbid layer collects on the bottom
of the fluid, while that collecting in the presence of chloroform is
yellowish. In the latter case, _i. e._, in the presence of chloroform,
the aqueous filtrate yields with lead acetate solution a white
precipitate (lead chloride and lead hydroxide). The adulterant having
thus been recognized, further particulars are learned from the specific
gravity of the oil as well as of the distillate.
Adulterations with _terpenes_ or _terpene-like fluids_, such as are
gained in the preparation of concentrated or patent oils, are difficult
to recognize. They may be detected by the specific gravity, the
terpenes being, as a rule, specifically lighter, their specific gravity
varying between 0.840 and 0.870.
The detection of _adulterations with volatile oils of a lower quality_
is very difficult, if not led to it by the odor and taste. Many methods
for establishing such adulterations have been proposed, of which the
following are the most important:--
I. _Test with iodine._--This test is based upon the fact that some oils
violently detonate with iodine, while others develop heat and vapors,
and others again remain indifferent. For this test pour upon about 0.19
gramme of dry iodine in a watch-crystal 4 to 6 drops of the oil to be
examined.
1. A vigorous reaction (detonation) with considerable increase in the
temperature and emission of vapors takes place with the following
oils: oils of bergamot, lemon, lavender, nutmeg, orange peel, spike,
turpentine, wormwood.
2. Such a reaction as mentioned under 1, does not take place with oils
of bitter almonds, copaiba, calamus, clove, peppermint, rose.
3. Moderate heating and slight vapors are developed with oils of
anise-seed, fennel, camomile, curly mint, marjoram, rosemary,
sassafras, thyme.
When an oil of the second series becomes heated with iodine and evolves
vapors, it may first of all be adulterated with cheaper oils. This may
also be the case when an oil of the third series reacts violently with
iodine and evolves vapors with strong heating. Formerly the iodine test
was highly valued; it has, however, been shown to be unreliable since
it is frequently dependent on the age of the oil.
In place of iodine, Rudolph Eck recommends a very dilute alcoholic
iodine solution, which is not discolored by oils of turpentine, while
other oils discolor it. Dissolve a drop of the oil to be examined in
3 cubic centimeters of 90 to 100 per cent. alcohol, and add a drop of
the iodine solution. The latter is not discolored in the presence of
an oil of turpentine. There are also, however, several volatile oils,
which do not discolor the iodine solution. Mierzinski mentions the
following: All cold-expressed oils from the _Aurantiaceæ_, further
oils of coriander, caraway, galanga, rue, sassafras, rose, rosemary,
anise-seed, fennel, calamus, neroli, angelica, wormwood. Hence, this
reaction cannot be relied upon.
II. _Hoppe's nitroprusside of copper test._--This test sometimes gives
good results, but only with hydrocarbons absolutely free from oxygen
and oxygenated oils. It is, therefore, not suitable for oils derived
from the _Aurantiaceæ_. The process is as follows: Add to a small
quantity of the oil to be examined in a perfectly dry test-tube, 2 to
5 milligrammes of pure nitroprusside of copper previously thoroughly
dried and finely pulverized, shake vigorously and gradually heat to
boiling. After boiling for a few seconds allow to cool. If the oil
is free from oil of turpentine, or another oil containing no oxygen,
the precipitate formed is brown, black, or gray, and according to the
quantity of the reagent added and the original color of the oil, the
supernatant oil will be differently colored and appear more or less
dark. If, however, the oil is adulterated with oil of turpentine,
the precipitate formed shows a handsome green or blue-green color,
while the supernatant oil retains its original color or at the utmost
acquires a very slightly darker one. The longer the oil is allowed to
stand after settling, the more distinct and beautiful the color of the
oil and of the precipitate appears. For the establishment and certain
recognition of very small quantities of oil of turpentine in oxygenated
oils, it is best to first add very little of the nitroprusside of
copper to the oil to be tested, and a larger quantity only after being
convinced either of the purity or adulteration of the oil. This is done
to be able, on the one hand, better to judge the reaction, if the oil
is pure, and, on the other, if it is adulterated, to establish such
adulteration with certainty and to approximately estimate the quantity
of oil of turpentine present. The less nitroprusside of copper is used,
the better small quantities of oil of turpentine can be detected.
Nearly all volatile oils free from oxygen show the same behavior
towards nitroprusside of copper; they decompose it, which is not the
case with oxygenated oils. The behavior of the latter is shown in the
following table:--
-------------+---------------+---------------+------------------+-------------
| | Proportion of | Color of the oil |
Name of | Color of the | nitroprusside | after | Color of the
the oil. | oil. | of | the experiment. | precipitate.
| |copper to oil. | |
-------------+---------------+---------------+------------------+-------------
Caraway |clear as water | 1 : 1000 parts|slightly | dirty gray.
| and colorless | | yellowish |
Fennel |pale yellowish | 1 : 1000 " |brownish-yellow | black.
Dill |pale | 1 : 1000 " |becomes first | "
| reddish-yellow| | colorless, then |
| | | yellowish | "
Anise-seed |pale yellow | 1 : 1000 " |yellow |
| | | " |
Camomile | | | |
(green) |yellowish | 1 : 1000 " |brownish-yellow | ash-gray.
Lavender |pale yellow | 1 : 1000 " |wine-yellow | slate-gray.
" | " | 1 : 100 " |brown-yellow | "
Mint (curly) |colorless | 1 : 1000 " |wine-yellow | first gray,
| | | | then black.
Peppermint | " | 1 : 1000 " |yellowish | black.
" | " | 1 : 100 " |brownish-yellow | "
Balm |yellow | 1 : 1000 " |dark wine-yellow | "
Marjoram |colorless | 1 : 1000 " |yellowish | "
" | " | 1 : 100 " |brown-yellow | "
Sage |slightly | 1 : 1000 " |wine-yellow | dark green.
| yellowish | | |
" | " | 1 : 100 " |brown-yellow | dark green,
| | | | then nearly
| | | | black.
Thyme (field)| " | 1 : 1000 " |brownish-yellow | slate-gray.
" | " | 1 : 100 " |dark brown-yellow | nearly black.
Wormwood |yellow-brown | 1 : 1000 " |dark brown | black.
Tansy |pale yellow | 1 : 1000 " |red-brown | dirty brown.
Milfoil |dark | 1 : 1000 " |first pale blue, | gray-brown.
| azure-blue | | then dark green |
Cajeput |colorless | 1 : 1000 " |brownish-yellow | black.
Clove |slightly | 1 : 2000 " |rose-red and clear| slate-gray.
| yellowish | | |
" | " | 1 : 1000 " |violet-red and | "
| | | clear |
" | " | 1 : 500 " |cherry-red | "
| | | and opaque |
" | " | 1 : 100 " |dark cherry-red | "
| | | and opaque |
Cassia |brownish-yellow| 1 : 1000 " |brownish-red to | black.
| | | hyacinth-red |
" | " | 1 : 100 " |dark brown-red | "
Sassafras |yellowish | 1 : 1000 " |yellowish-brown | "
Star anise |pale yellow | 1 : 1000 " |dark wine-yellow | "
Valerian |pale greenish | 1 : 100 " |brownish-yellow | "
Rue |slightly | 1 : 100 " |brown-yellow | ash-gray.
| yellowish | | |
Bergamotte |yellowish | 1 : 1000 " |dark yellow | "
" | " | 1 : 100 " |brownish-red | "
-------------+---------------+---------------+------------------+-------------
If these oxygenated oils are mixed with oils free from oxygen, for
instance, oil of turpentine, they show exactly the same behavior as
oils free from oxygen; the nitroprusside of copper is not decomposed
and retains its gray-green color. If, for instance, oil of cloves is
mixed with oil of turpentine, the red coloration by nitroprusside of
copper does not appear.
III. _Hager's alcohol and sulphuric acid test._--Bring into a test-tube
of about 0.5 inch diameter, five to six drops of the oil to be tested
and twenty-five to thirty drops of pure concentrated sulphuric acid,
and mix the two fluids by shaking, whereby either no heating takes
place or a scarcely perceptible one, or the heating is strong or very
vigorous and in some cases increased to the evolution of vapors. The
mixture is either clear or turbid. After complete cooling, add to the
mixture eight to ten cubic centimeters of 90 per cent. alcohol, and
after closing the tube with the finger, shake vigorously. The mixture
now shows a different color, is clear or turbid, and the deposit formed
after standing for one day is also differently colored and either
soluble or insoluble in boiling alcohol.
The mixture of oil, sulphuric acid and alcohol is perfectly clear
and transparent with oils of bitter almonds, fennel, clove and rose;
with anise-seed oil and star anise-seed oil only the alcoholic layer
over the mixture of sulphuric acid and oil is clear. The mixture of
oil, acid and alcohol is slightly turbid or nearly clear with oils
of valerian, peppermint and field thyme. With most of the other
volatile oils occurring in commerce, the mixture is more or less milky
turbid. Heating of the oil and acid mixtures does not take place with
pyrogenous oils (petroleum, benzine) or only to a very slight degree,
as with oils of peppermint and mustard.
IV. _Hager's guaiacum reaction_[3] serves for the detection of oil of
turpentine in a volatile oil. By pouring upon as much guaiacum, freshly
powdered, as will lie upon the point of a small knife, in a test-tube 1
cubic centimeter (25 drops) of spike oil, and heating nearly to boiling
over a petroleum lamp, the oil after being removed from the flame and
allowing the undissolved resin to settle, shows a _yellow_ color. By
now pouring upon an equal quantity of guaiacum in another test-tube 25
drops of spike oil and 5 drops of rectified oil of t from the flame
shows a _dark violet color_. Various other oils behave in the same
manner as spike oil, and hence a content of oil of turpentine can be
readily detected in them. Other oils do not exhibit this behavior; but
this can be remedied by adding, in testing for oil of turpentine, a few
drops of an oil of the first class.
[3] Hager, Chemische Reactionen zur Nachweise des Terpentinoels in den
aetherischen Oelen, etc. Berlin, 1885.
The guaiacum reaction is an ozone reaction and with reference to this,
the volatile oils may be divided into three classes:--
_a. Oils inclining to the formation of ozone._--Foremost of these is
oil of turpentine, especially when rectified. Oils of tansy, rue, mint,
juniper, zedoary, etc., show considerably less inclination.
_b. Oils which, especially when heated, directly incite the oil of
turpentine to form ozone, and to color guaiacum violet or blue._--Such
oils are many kinds of oil of citronella, oils of spike, calamus,
cedar, etc.
_c. Oils with a content of oil of turpentine, which remain indifferent
towards guaiacum._--To such oils, if to be tested for oil of
turpentine, with the assistance of the guaiacum reaction, a few drops
of an oil of the second class have to be added.
V. _Hübl's iodine method._--Mr. C. Barenthin has applied Hübl's iodine
method for fixed oils to the examination of volatile oils. He uses the
following solutions:--
1. Fifty grammes iodine and 60 grammes of mercuric chloride in a liter
of alcohol freed from fusel oil, and let stand for 12 hours.
2. Twenty-four grammes of hyposulphite of sodium in a liter of water.
3. A ten per cent. solution of iodide of potassium. Dissolve 0.1 to
0.2 gramme of the volatile oil in 10 cubic centimeters of chloroform,
and add first 15 cubic centimeters of the iodine-mercuric chloride
solution; let stand three or four hours, and, in case the mixture gets
discolored, add a few more centimeters of solution. Now add 10 to 15
cubic centimeters iodide of potassium solution, dilute with 150 cubic
centimeters of water, and titrate with hyposulphite till the mixture
remains clear for about a minute. The iodide of potassium solution
must be added before the water, and the relative proportions between
this solution and the iodine-mercuric chloride solution must be 15
to 20 cubic centimeters. The quantity of iodine solution consumed is
calculated to iodine for 100 parts and the figure thus obtained is
designated as the "iodine number."
Barenthin has in this manner determined the iodine number of several
volatile oils; other experimenters, however, for instance, Kremel and
Davies,[4] have found different numbers for the same oils, so that
this method requires further thorough examination before it can be
classed as available.
[4] Pharm. Centralh. 1888, S. 482 u. 555; 1889, S. 133.
VI. A. Kremel has endeavored to utilize _titration or saponification
with alcoholic potash lye_ for the examination of volatile oils. In his
experiments he was guided by the following points: A series of volatile
oils contains partially free organic acids, like oils of bitter almonds
and cinnamon, and partially aldehydes or other combinations. Now it
seems not impossible, that up to a certain limit, the quantities of
these combinations in the separate volatile oils remain constant, thus
presenting the opportunity of testing the respective oils as to their
quality and purity by saponification. In some cases these combinations
are the chief bearers of the specific odor, and hence the determination
of the "_saponification number_" becomes of double value. It is, of
course, self-evident that not every volatile oil can be saponified, and
Kremel admits that, even where saponification takes place, it is not in
every case a sure test.
The execution of the method is as follows: Dissolve 1 gramme of
the oil to be examined in 2 to 3 cubic centimeters of 90 per cent.
alcohol freed from acid, compound the solution with a few drops of
phenol-phthalein solution, and titrate the free acid with ½ normal
alcoholic potash lye. The milligrammes of caustic potash used are
designated the "_acid number_." After having thus determined the
content of acid, add to the same solution 10 cubic centimeters of
the same potash lye, heat for ¼ hour upon the water bath, and then
titrate back the excess of potash lye with ½ normal hydrochloric
acid. In this manner the "_saponification number_" is obtained. (In
some cases when the final reaction is not plainly perceptible, it
is advisable to correspondingly dilute with water after heating the
alcoholic fluid.) The saponification number, less the acid number,
gives the "_ether_ or _ester number_."
Kremel has in this manner examined a large number of volatile oils and
partially obtained surprising results. Rose oil gives a saponification
number of 12, and geranium oils one of 40 to 50. While lavender
oils give very high saponification numbers, oil of lemons does not.
Artificial oil of bitter almonds shows higher saponification numbers
than the natural oil. By further compounding the saponified portions of
the latter with acid, a crystalline precipitate of benzoin is formed,
the quantity of which amounts to from 40 to 50 per cent. of the oil
used. Such a precipitate, but only in very small quantities, is also
formed in peach kernel oil, but not in other similar oils nor in
artificial oil of bitter almonds.
VII. F. R. Williams has recently endeavored to utilize for testing
volatile oils Maumené's test, which is based upon the increase in
temperature produced in oils by concentrated sulphuric acid, and
which gives valuable points for the examination of some fat oils. Of
course, the large quantities of oil otherwise prescribed cannot be
used. While for the examination of fat oils 50 grammes of oil are mixed
with 10 cubic centimeters of concentrated sulphuric acid in a beaker
glass wrapped around with cotton, Williams could use only six cubic
centimeters of volatile oil. They were brought into a very small beaker
glass enveloped in cotton. After reading off the temperature, twelve
cubic centimeters of concentrated sulphuric acid were added and the
whole stirred with the thermometer until the temperature no longer
rose. Numbers were in this manner obtained which might in some cases,
for instance, cassia oil, furnish guiding points for judging the purity
of the oil.
Planchon proposes the following procedure in order to recognize a
volatile oil:--
A. _The oil is specifically lighter than water._
1. The substance is solid and only melts at 347° F.: _Camphor_.
2. The oil at a temperature of over 32° F. contains a crystalline
stearoptene.
_a._ The oil is laevorotatory, the stearoptene melts at 77° F., and,
on adding sulphuric acid, a clear solution remains behind: _Rose oil_.
_b._ The oil possesses no rotatory power, the stearoptene melts at 50°
F., and, on adding sulphuric acid, two layers are formed, only one of
which is liquid: _Anise-seed oil_.
_c._ The oil is dextrorotatory, the stearoptene melts at 41° F., and,
on adding sulphuric acid, a nearly colorless fluid remains behind:
_Fennel oil_.
3. The oil is perfectly fluid and clear at above 32° F.
I. The oil explodes with iodine, emitting violet vapors.
_a._ The oil thickens in the air and readily forms resin. It requires
for its solution several volumes of alcohol: _Oil of conifers_.
_b._ The oil, on exposure to the air, does not thicken and but slowly
forms resin.
α. It is dextrorotatory.
The liquid oil dissolves santalin: _Oil of the aurantiaceæ_.
The thick oil does not dissolve santalin: _Mace oil_.
β. The oil is laevorotatory.
The oil shows an acid reaction and dissolves in equal parts of
alcohol: _Lavender oil_.
The oil shows a neutral reaction and dissolves in 12 to 15 parts of
alcohol: _Marjoram oil_.
II. The oil gives no explosion with iodine, but shows an increase in
temperature with or without emission of red vapors.
_a._ The oil shows an acid reaction.
α. The blue or green oil shows the acid reaction only
indistinctly: _Milfoil oil_.
β. The colorless or brown oil gives a turbid fluid with sulphuric
acid. It is laevorotatory: _Spanish marjoram oil_.
The oil is rendered but slightly turbid by sulphuric acid; it acquires
a red-violet color by nitric acid, has no effect upon the plane of
polarization, and has a peculiar odor: _Oil of valerian_.
_b._ The oil is neutral.
α. It dissolves with difficulty in alcohol.
β. The oil is miscible in every proportion with alcohol.
1. It is dextrorotatory.
The oil is colorless or yellowish, it thickens on exposure to the air,
and dissolves and reduces fuchsine: _Caraway oil_.
The oil is thick, yellow-brown or red-yellow, and has a peculiar odor:
_Calamus oil_.
2. The oil is laevorotatory.
It is fluid and has an aromatic odor: _Rosemary oil_.
The oil is thick and very pungent: _Cubebs oil_.
III. The oil dissolves iodine without vigorous reaction and without an
increase in the temperature.
_a._ The oil is blue and green.
It has an agreeable, camphor-like odor: _Camomile oil_.
The green oil thickens in the air and is dextrorotatory: _Wormwood
oil_.
The oil is generally green and produces no effect upon the plane of
polarization: _Cajeput oil_.
_b._ The oil is colorless or yellow-brown.
α. It separates a solid stearoptene at about 32° F.: _Rue oil_.
β. The oil remains liquid at several degrees below 32° F.
1. Dextrorotatory oils.
The oil shows an acid reaction, and gives with sulphuric acid a
somewhat turbid solution, which becomes clear by the addition of
alcohol: _Dill oil_.
The oil gives with sulphuric acid a yellow-red turbid solution, which
becomes clear and peach-blossom red by the addition of alcohol:
_Eucalyptus oil_.
2. Laevorotatory oil.
The oil showing an acid reaction becomes thick in the air and has a
characteristic odor: _Mint oil_.
The oil shows a neutral reaction and has a camphor-like odor:
_Thyme oil_.
IV. The oil does not dissolve iodine, does not heat with sulphuric
acid, and does not react upon nitric acid. The odor is empyreumatic:
_Petroleum_.
B. _The oil is specifically heavier than water._
1. The oil shows an acid reaction.
It is soluble in 30 parts of water, boils at 356° F., and smells of
bitter almonds: _Oil of bitter almonds_.
The oil has an agreeable, sweet odor and boils at from 392° to 431.6°
F.: _Wintergreen oil_.
2. The oil shows a neutral reaction.
_a._ The oil is laevorotatory.
It becomes blue by the addition of sulphuric acid: _Oil of cloves_.
_b._ The oil is optically inactive.
The thick oil gives with sulphuric acid a turbid, black-brown fluid;
the odor is agreeable: _Cinnamon oil_.
_c._ The oil is dextrorotatory.
The thick oil has an agreeable odor: _Sassafras oil_.
CHAPTER IV.
THE VOLATILE OILS USED IN PERFUMERY.
The volatile oils, as previously mentioned, may be divided into three
groups, viz: the pure hydrocarbons, oxygenated oils, and sulphuretted
oils. Chemically, this division is, however, of little value, since,
among bodies which should be classed according to it in one of the
groups, combinations are found which vary very much in a chemical
respect, and belong partially in the groups of alcohols, indifferent
bodies, acids, etc.
It is, therefore, preferred not to attempt a classification of the
volatile oils according to their chemical composition, but simply to
enumerate them in alphabetical order.
_Acacia, oil of_, commonly called _oil of cassie_. The flowers or
buds of the _acacia Farnesiana_ yield a somewhat thickly-fluid,
greenish-yellow oil of a very intense but delightful odor. The oil
may be obtained either by extraction or absorption. The acacia is
cultivated in special plantations along the _Riviera di Genova_. These
plantations being controlled by a few perfumers, the oil is not allowed
to reach the market, and does not form an article of commerce. The
green-colored _extrait d'acacia_ is a solution of the oil in alcohol.
_Almond oil_ (_bitter_) (_oleum amygdalæ amaræ_) is obtained by
submitting bitter almond cake (left after the expression of the fixed
oil from bitter almonds) to distillation with water. The volatile
oil does not exist ready formed in the bitter almond, nor in the
almond cake, but results from the decomposition of a glucoside called
"amygdalin," contained in the cake, under the influence of emulsin and
water, the emulsin acting as a ferment, into benzylic aldehyde, glucose
and prussic acid. The almond tree grows wild, but is also cultivated
in Southern Europe, Africa, Barbary, Palestine and Syria. The bitter
almonds brought from Barbary are considered the best. Besides, in
almonds, amygdalin occurs in various other plants; for instance, in
the leaves of the cherry laurel, the leaves and kernels of the peach,
the kernels of the black cherry and other varieties of _prunus_
and _amygdalus_, they all yielding, after maceration with water, a
distillate containing prussic acid and oil of bitter almonds.
Instead of the comparatively expensive bitter almonds, peach kernels
freed from their hard shells are extensively used in the fabrication
of oil of bitter almonds. The oil is prepared as follows: The press
cakes of bitter almonds or peach kernels are ground and soaked about
twenty-four hours in twice their weight of water to which one-third
their weight of salt has been added. The whole is then submitted to
distillation. The temperature of the water should not exceed 113° to
122° F. The emulsin contained in the almonds possesses only within
certain limits of temperature the power of decomposing amygdalin,
and, if heated to 176° F., becomes inoperative. Hence, if the almond
paste is quickly heated to boiling, the emulsin becomes inoperative
before all the amygdalin is decomposed, and a portion of it being
consequently lost, the yield is insufficient. The distillation of the
almond paste is effected in a current of steam.
A portion of the prussic acid formed by the decomposition of the
amygdalin adheres tenaciously to the oil. This content of prussic acid
makes the oil of bitter almonds exceedingly poisonous, while in itself
it is non-poisonous. It can be freed from the prussic acid by shaking
with ferrous sulphate (blue vitriol) solution. By then distilling
over burnt lime the originally yellow or yellowish oil is obtained
colorless. It is then thinly fluid, of a peculiar agreeable odor and
strongly nutty taste. Its specific gravity is 1.043 at 59° F., but
varies a little with age. It boils at 356° F., and dissolves in 13
parts of water, but more readily in alcohol and ether. In the air it is
rapidly converted into benzoic acid by the absorption of oxygen. It has
to be carefully protected from air and light and kept in well-closed
bottles in a dark place. The crude oil, containing from 2 to 5 per
cent. prussic acid, has generally a yellowish color.
Oil of bitter almonds may be prepared artificially in many ways. By
allowing chlorine to flow into boiling toluene, the latter is converted
into benzyl chloride:-
C_{6}H_{5}(CH_{3}) + Cl_{2} = C_{6}H_{5}(CH_{2}Cl) + HCl
└----toluene-----┘ └-benzyl chloride--┘
chlorine hydrogen
chloride
By withdrawing the chlorine and one atom hydrogen from the benzyl
chloride and introducing for it one atom oxygen, the benzyl chloride
is converted into benzaldehyde. This conversion is readily effected
by continuously boiling, best with the introduction of carbonic acid,
1 part of benzyl chloride with 1½ parts of lead nitrate and 10 parts
of water, and finally distilling the benzaldehyde off by steam. The
decomposition takes place according to the following equation:--
2[C_{6}H_{5}(CH_{2}Cl)] + Pb(NO_{3})2 =
2[C_{6}H_{5}(CHO)] + PbCl_{2} + N_{2}O_{3} + H_{2}O.
The crude benzaldehyde thus obtained is agitated with warm solution
of acid sodium sulphite, the solution formed thereby is separated
from undissolved oily particles and cooled, whereby a combination
of benzaldehyde with acid sodium sulphate crystallizes out. This
combination is separated from the remaining fluid, decomposed by acid
and submitted to distillation, whereby benzaldehyde passes over. Large
quantities of benzaldehyde are at present prepared according to this
method. The identity of benzaldehyde with oil of bitter almonds has
been established by Lippmann and Hawliczek.
Genuine oil of almonds is much adulterated, chiefly with alcohol,
nitrobenzole, and various cheaper oils. An addition of 3 to 5 per cent.
of alcohol is frequently made by Italian dealers in order to conceal a
content of water, which at a low temperature is apt to render the oil
turbid. To detect the presence of alcohol, moderately heat a sample
of the oil in a distilling apparatus and compound the drops, first
passing over with sodium carbonate solution and then with potassium
iodide solution. In the presence of alcohol a yellowish crystalline
precipitate of iodoform is formed.
An addition of synthetically composed oil might seem of no importance,
since the natural oil does not differ from it. However, for very
fine perfumery the natural oil cannot be replaced by the artificial,
it having been thus far impossible to obtain the latter absolutely
chemically pure. It always contains small quantities of undecomposed
chlorine combinations which injure the taste and odor. To detect such
oil in the natural oil, bring a few drops upon a tuft of cotton and
ignite it. Over the burning flame invert a beaker moistened inside with
water. On the moist sides of the beaker the soot and hydrochloric acid
formed by the combustion of the chlorine combination are precipitated.
When the flame is extinguished, the beaker is rinsed out with water,
the fluid filtered and tested for chlorine with nitrate of silver.
An addition of 10 per cent. artificial oil can in this manner be
accurately determined.
If genuine oil of bitter almonds containing prussic acid, be heated
with an excess of alcoholic potash lye, and the excess of the latter
be neutralized with hydrochloric acid, benzoin amounting to 40 to 50
per cent. of the weight of oil of bitter almonds is, according to A.
Kremel, separated. By subjecting artificial oil of bitter almonds to
the same treatment, no benzoin is separated, so that the genuine oil
can in this manner be distinguished from the artificial. Kremel further
found that oil of bitter almonds prepared from apricot kernels, when
treated in an analogous manner, yielded considerably less benzoin,
and that cherry-laurel oil containing prussic acid, which has been
considered identical with oil of bitter almonds, separated no benzoin
whatever. Should further experiments prove the constancy of this
phenomenon, this reaction would be a convenient means of distinguishing
the four products.
An adulteration with nitrobenzole and other volatile oils is recognized
by mixing 2 drops of the oil with 100 drops of distilled water,
and shaking vigorously. Pure oil must completely dissolve. However,
the test yields accurate results only with the use of actually pure
distilled water and by accurately observing the above-mentioned
proportions. If to 5 cubic centimeters of 90 per cent. alcohol and
an equal quantity of distilled water in a test-tube, 10 drops of the
oil be added, and, after closing the tube with the finger, mixture be
effected by gently turning the tube twice upside down, a clear solution
will immediately result if the oil is pure. If, however, it contains
nitrobenzole, even only 1 per cent., the latter separates, at first
rendering the fluid turbid, but in the course of a minute, when gently
agitated, it floats in the form of minute drops upon the fluid, while,
when at rest, these drops collect to larger ones on the bottom of the
test-tube. If the oil becomes only turbid, adulteration with other
volatile oils is indicated. Another test, given by Wagner, is based
upon the difference in the specific gravity of mixtures of oil of
bitter almonds with oil of mirbane. The specific gravity of commercial
oil of bitter almonds varies between 1.040 and 1.043 and that of oil
of mirbane between 1.180 and 1.201.
5 c. c. of pure oil of bitter almonds weigh 5.29 grammes.
5 " mixed with ¼ oil of mirbane " 5.39 "
5 " " " ½ " " " 5.57 "
5 " " " ¾ " " " 5.75 "
5 " of pure " " " 5.90 "
Oil of bitter almonds is much used in the fabrication of perfumery. In
a pure state its odor is by no means agreeable, but rather strong and
stupefying. When strongly diluted it is, however, very pleasant.
_Angelica oil_ is obtained by distillation with water from the root
of _Angelica Archangelica L._, natural order _Umbelliferae_. The oil
is lighter than water, possesses the spicy odor of the root and an
aromatic pungent taste. It consists mostly of a terpene which turns the
plane of polarization to the right, and boils at 320° F.
Besides the oil from the root, one obtained from the seeds also occurs
in commerce. It is, however, more expensive. In a fresh state it is
amber-yellow, and has a specific gravity of 0.8549 at 59° F.; older
oil is thickly-fluid, brown, and has a specific gravity of O.9086. It
contains a terpene which turns the plane of polarization to the right,
and has a lemon-like odor. It is used for fine perfumery.
_Anise-seed oil_ (_oleum anisi_). The anise (_Pimpinella anisum L._),
natural order _Umbelliferae_, contains volatile oil in all parts, but
chiefly in the seeds. Dry anise-seed yields by distillation 2½ to 3 per
cent. of oil, while the peduncle and chaff contain at the utmost 1 per
cent. of oil, which is said to be richer in stearoptene. The anise-seed
oil prepared in Southern Russia has always been highly valued, but as
it is generally considerably adulterated, the Leipsic manufacturers of
volatile oils prefer to import the seed and distill it themselves.
Freshly prepared anise-seed oil is colorless or straw-yellow, has the
odor of anise and a sweetish taste, leaving a burning sensation upon
the tongue. It is thinly fluid at 68° F., but commences to congeal
at a somewhat lower temperature, and the sooner the more stearoptene
it contains. Good oil should become solid at from 57.2° to 60.8° F.
It has a specific gravity of 0.980 to 0.995 at 59° F. The specific
gravity varies with the content of stearoptene; the greater the latter
the higher the specific gravity. Good anise-seed oil contains 5 to 10
per cent. of terpene and 90 to 95 per cent. of a stearoptene, called
anethol, C_{10}H_{12}O, on which the value of the oil depends. The
anethol can be separated from the oil by cooling to 32° F., and forms
colorless crystals. It has an agreeable odor and intensely sweet taste,
is sparingly soluble in water, but readily in alcohol, ether, and other
solvents of volatile oils. Good anethol has a specific gravity of
0.986, and melts at 69° to 70° F. By frequent contact with the air a
small portion of the anethol is oxidized, very likely to anisaldehyde.
By this process the specific gravity is raised and the melting point
lowered.
Anise-seed oil is soluble in 5 parts of 90 per cent. alcohol, and with
3½ times its volume of petroleum-ether yields a clear mixture. Its
mixture with four times its weight of petroleum-ether is turbid, but
becomes clear in ten minutes, while that with five times its volume of
petroleum-ether remains for a longer time turbid. In a fluid state the
oil, when exposed to the air, becomes resinous and loses its property
to crystallize. It should, therefore, be kept in tightly-closed bottles
in a cool, shady place.
Anise-seed oil is used in perfuming soaps and mouth waters. It should,
however, be used with prudence, since the sweetish, penetrating odor of
the oil readily overcomes the other volatile oils in the mixture, and
renders them inoperative.
_Star anise oil_ very much resembles the ordinary anise-seed oil. It
is obtained from star anise, the fruit of _Illicium anisatum_, a tree
formerly supposed to be indigenous to Cochin China, and cultivated in
China, Japan, and the Phillipine Islands. However, according to Messrs.
Bourgeoin-Meiffre, a French firm of Hanoï (Tonkin), the star anise oil
found in commerce is exclusively produced in the French colony Tonkin
(Province Langson), the French government having made over the entire
sale of the oil to the above-mentioned firm.
According to a memoir published by Dr. Blondel, of Paris, the star
anise tree is not indigenous to the Chinese provinces Yunnan, Quang-si,
and Fo-Rien, but to the province Langson, which has by conquest passed
into French possession. Hence, the producers of star anise and star
anise oil are now under French control and, as it seems, are obliged
to sell all the oil produced to the above-mentioned firm. If these
statements should prove correct, the Chinese harbors Macao and Hong
Kong, from which the greater portion of star anise oil was formerly
exported, will lose their importance in this respect and the product
find its way direct from Hanoï _via_ Hayphong to Marseilles. The first
shipment from Bourgeoin-Meiffre arrived in Europe in December, 1890.
According to Messrs. Schimmel & Co.'s report, the product is put up and
packed exactly like that formerly shipped from Hong Kong, and the oil
of excellent quality.
Star anise oil differs from the ordinary oil in containing a much
smaller quantity of anethol, and hence congealing only at a temperature
of from 41° to 50° F. Besides the odor of the terpene contained in star
anise oil differs from that of the ordinary oil. Admixtures of star
anise oil can, therefore, be generally recognized by the odor. Other
methods recommended for its detection are unreliable.
_Balm oil._--The leaves of this plant, _Melissa officinalis_, yield
by distillation a volatile oil sometimes called oil of melissa. It is
colorless or yellowish, of a pleasant odor, has a specific gravity of
0.85 to 0.92, shows a slightly acid reaction and dissolves in 2 to 3
parts of alcohol. It must not be confounded with the so-called East
India oil of melissa or citronella oil from _Andropogon Nardus L._ Balm
oil is occasionally used in the preparation of _eau de Cologne_.
_Basil oil_ is distilled in Southern France from the fresh leaves
of _Ocymum basilicum L._, natural order _Labiatæ_. The oil shows
the peculiar odor of the herb and crystallizes a few degrees above
32° F. In perfumery it is used as an addition to violet and other
preparations. The French also prepare a _pommade basilique_, which
serves as a cheap substitute for violet pomade.
_Bayberry oil_, or _oil of bay leaves_, is extracted by distillation
from the leaves of _Myrcia acris_ or the bayberry tree. Many varieties
of the tree exist throughout the West Indies, which are scarcely to
be distinguished botanically, but have quite a different odor from
that of the genuine tree. Great care must, therefore, be taken in the
collection of the leaves which are to be used, as the admixture of a
small quantity of the other leaves may entirely spoil the product of
distillation. Two oils are obtained, a light oil of specific gravity of
0.870 to 0.990, and a heavy oil with specific gravity 1.023 to 1.037.
When first distilled the oil is colorless, but by exposure to the air
quickly acquires a yellowish tint and, if the exposure be continued,
becomes quite dark in color. The odor of the freshly-distilled oil is
rank, but in the course of from three to six months it becomes mellow,
and ripens into the agreeable fragrance so much liked in the best
specimens of bay-rum. The oil is soluble in all proportions in 95 per
cent. alcohol, also in ether and petroleum benzine. Its chief use is
for the preparation of bay-rum.
_Bergamot oil_ is obtained from the rinds of the fruit of _citrus
bergamia_, a tree belonging to the natural order _Aurantiaceæ_. The
rind is grated and the oil running off separated from the aqueous
fluid and cellular substance by means of a separating funnel, or
the grated mass is distilled in a current of carbonic acid. The oil
is very fluid and pale yellow, but poorer qualities are frequently
greenish or brownish. When distilled with water it becomes perfectly
colorless, but is less durable. Its odor is very pleasant, somewhat
like a mixture of orange and lemon oils. Its specific gravity is 0.87
to 0.89. By standing for some time, the oil separates white crystalline
scales (stearoptene), which melt at 223° F. The oil becomes solid a
few degrees below the freezing point. The Messina oil of bergamot is
considered the best. From other volatile oils of the orange family,
bergamot oil differs in dissolving readily in caustic potash, forming
a clear solution. It has, however, the same property as other oils of
a similar origin, of igniting with iodine and not dissolving santalin,
the red resinous coloring matter of santal-wood.
Bergamot oil may be tested as to its purity by mixing it with alcohol.
It becomes pale gray-yellow, forms a sediment which adheres firmly to
the vessel and, on shaking, floats about in the form of flakes. After
two days the sediment is inconsiderable and difficult to divide into
flakes in the clear yellow fluid by shaking. The oil is frequently
adulterated with alcohol. To detect such adulteration, Righini
recommends the following method: Mix 15 parts of the oil with a like
quantity of pure olive oil or oil of sweet almonds. If alcohol is
present, it immediately separates, like water, from the fat oil; if no
separation takes place the oil is not adulterated with alcohol. The
tannin test also gives reliable results. In storing oil of bergamot
great care must be exercised to exclude air and light, as it is one of
the most changeable oils and soon acquires an odor resembling that of
turpentine.
Large quantities of oil of bergamot are used in perfumery. It forms, so
to say, the basis for most of the finer products. In Cologne water it
forms the principal constituent in the mixture of volatile oils.
_Cajeput oil_ (_oleum cajeputi_).--This oil is obtained by distillation
from the leaves of several species of _Melaleucæ_, natural order
_Caryophyllaceæ_, indigenous to the East Indies, Banda, and Malabar.
The ordinary oil has a greenish color and possesses a strong odor
of camphor and a pungent taste. It is chiefly imported by way of
Amsterdam, where it is partially discolored by rectification, so
that two kinds, the white and green cajeput oil, are brought into
commerce. The color of the latter is generally supposed to be due to a
resinous substance containing chlorophyl, though others assert that it
originates from the copper of the distilling apparatus and the copper
flasks in which it is dispatched. The specific gravity of the oil
varies between 0.910 and 0.940, though specifically lighter and heavier
oils are said to occur.
It is claimed that an artificial cajeput oil is often prepared
from camphor and rosemary oil, the green color being obtained by
distillation with milfoil. The presence of camphor may be readily
determined by thoroughly triturating a few drops of the oil with sugar
and then dissolving in water, whereby the particles of camphor separate
in the form of white flakes upon the surface.
Cajeput oil is frequently adulterated with oil of turpentine and
rosemary oil. Such adulteration is recognized by pure cajeput oil
dissolving clear in equal parts of 90 per cent. alcohol, which is not
the case with the other two oils.
_Camomile or chamomile oil_ (_oleum anthemidis_).--Two varieties of
oil of camomile are found in commerce, one green and the other blue.
The first is derived from the flowers of the genuine or Roman camomile
(_Anthemis nobilis_) and the blue from the common variety (_Matricaria
chamomila_). The last oil is the one chiefly used in the manufacture of
perfumery and in medicine.
_Blue camomile oil_ is generally obtained by distillation. In
distilling, metal Florentine flasks should be used, as the oil adheres
tenaciously to glass vessels and the distillate has to be treated with
ether. The pure oil has a beautiful blue color, and on heating forms
blue vapors. It has a penetrating odor which only by strong dilution
becomes similar to that of camomile. By storing in the light and the
simultaneous presence of air, the oil turns green; later on, brown, and
is finally converted into a thickly-fluid, brownish mass.
_Green camomile oil_ from the genuine or Roman camomile possesses an
agreeable odor of fresh lemons; it is more seldom used than the other.
On account of the slight yield obtained from the flowers, camomile oil
is rather expensive.
_Caraway oil_ (_oleum carui_) is obtained by distillation from the
seeds of the well-known aromatic plant _Carum carui_, or the caraway,
natural order _Umbelliferae_. In a fresh, purified state the oil is
colorless, very thinly-fluid and possesses a pungent taste. The oil
prepared from cleansed Dutch seed is best liked, while that distilled
from Norwegian or Tyrolese seed is not much in demand, its taste and
odor not being so pure on account of the many impurities mixed with
these kinds of seed.