THE CHEMICAL PRODUCTS USED IN PERFUMERY.
In the manufacture of perfumery a considerable number of chemical
products find application; in this place, however, we shall describe
only those which are used very frequently and generally, and discuss
the characteristics of those employed more rarely in connection with
the articles of perfumery into which they enter. According to their
application we may divide these substances into several groups, namely:
A. Chemicals which, without themselves serving as perfumes, are used
exclusively for the extraction of odors.
B. Chemicals which, while not fragrant, are frequently employed in the
preparation of perfumes. Under this head we have included also those
substances which are not strictly chemical products, but originally
come from the animal or vegetable kingdom, such as fats, spermaceti,
and wax, yet cannot be used in perfumery unless they have undergone a
process of chemical purification.
C. Chemical products used for coloring perfumes, so-called dye-stuffs.
The greater portion of the substances to be here described it will
hardly be the province of the perfumer to prepare himself, as they are
furnished by chemical factories at low prices; but some of them—for
instance, sublimed, natural benzoic acid suitable for perfumery and a
few other substances—the perfumer should make himself, in order to be
sure of its genuineness. Therefore, while in the former class it will
be sufficient to describe their properties to enable the manufacturer
to distinguish good quality from bad, the latter class must be
discussed at greater length.
A. Chemicals used for the Extraction of Aromatic Substances.
For the extraction of aromatic substances from plants a number of
bodies are used which possess great solvent power for essential oils,
and are besides very volatile, or have a low boiling-point. These are
particularly ether, chloroform, petroleum ether, and bisulphide of
carbon.
ETHER.
This liquid, in commerce also called sulphuric ether, is made in large
quantities in chemical laboratories by the distillation of alcohol with
sulphuric acid, followed by a second distillation or rectification.
When pure, ether forms a mobile, thin, strong-smelling, and inflammable
liquid which when inhaled produces insensibility, for which reason it
is used as an anæsthetic in surgery. Its specific gravity is about
0.720 when anhydrous, and its boiling-point 35° C. (95° F.). It forms
an excellent solvent for essential oils, resins, fats, and similar
bodies. Owing to its great volatility, its vapors are quickly diffused
in the air, and, as they are very inflammable, lights must be kept away
from a bottle containing this substance. The same remark applies to
most of the substances to be presently described.
CHLOROFORM
is prepared by the distillation of chlorinated lime, alcohol, and
water, acetone being more recently substituted for the alcohol,
followed by rectification of the product. When inhaled it produces
insensibility like ether. It has a pleasant odor and sweet taste. Its
specific gravity is about 1.49 and its boiling-point 61° C. (142° F.).
Owing to its great solvent power and low boiling-point, chloroform is
largely used for the extraction of aromatic vegetable substances; it
does not take fire directly in the air.
PETROLEUM ETHER.
Petroleum, which is brought into commerce in immense quantities,
especially from Pennsylvania, for illuminating purposes, cannot be used
in its crude state, but requires rectification. Petroleum as it issues
from the earth consists of various hydrocarbons mixed together, some of
which have very low boiling-points, so that their vapors readily take
fire and would make the use of petroleum in lamps dangerous. Petroleum,
therefore, is heated in large apparatuses to about 70 or 80° C. (158 to
176° F.), when the more volatile products pass over, and the petroleum
for illuminating purposes remains in the stills. A certain fraction
of the volatile distillate, the so-called petroleum ether, is largely
used in the manufacture of varnishes. Owing to its great solvent power
for aromatic vegetable substances and its low price, petroleum ether
has become quite an important body for the extraction of perfumes,
which will be further discussed hereafter. Good petroleum ether is
colorless, has a peculiar, not unpleasant odor and a boiling-point
between 50 and 55° C. (112° and 131° F.).
BENZIN
is a common name for another fraction of the volatile distillate from
petroleum, viz., that which boils between 50° and 60°C. (122° to 140°
F.) and has a spec. grav. of 0.670 to 0.675°.
This liquid, which is also used as a volatile solvent for the
extraction of odorous substances, must not be confounded with Benzene
or Benzol, a distillate from coal tar, boiling at about 80° C. (176°
F.) and having a spec. grav. of 0.878. The latter is not used for the
extraction of perfumes.
BISULPHIDE OF CARBON.
This is made by conducting vapors of sulphur over glowing charcoal
or coke. The vapors of bisulphide of carbon thus formed are led into
vessels filled with ice or ice-cold water, where they condense.
Bisulphide of carbon is a colorless liquid, heavier than water and very
refractive. It is inflammable, and possesses a peculiar odor which
is not disagreeable if the liquid has been thoroughly purified. Its
boiling-point is about 45° C. (113° F.) and it has great solvent power.
At the present time, the market affords bisulphide of carbon of a high
degree of purity.
Some manufacturers who prepare their odors by extraction, may find it
advantageous to make also the bisulphide of carbon necessary for it,
and this is best done in Gérard’s apparatus (Fig. 1). It consists of
a cast-iron cylinder _a_, two metres high and one metre in diameter.
This cylinder is heated on the outer surface in an oven, and two tubes,
_c_ and _d_, are attached to it. Tube _d_ is connected by _e_ with
the hemispherical vessel _b_ which is connected by the tube _i_ with
the condenser _mlk_. The condenser is formed of three cylinders made
of sheet zinc which are surrounded with cold water. The condensed
liquid escapes into the vessel _p_, while the gaseous products pass
through _n_ into the chimney. The cylinder _a_ is filled with about
1,500 pounds of charcoal or coke in small pieces, after which it is
closed and all tubes are carefully luted with clay; _a_ is then heated
to a strong red heat and at intervals of three minutes 3 pounds of
sulphur are thrown in through _c_. In twenty-four hours, by the use of
478 pounds of sulphur, 568 pounds of crude bisulphide of carbon are
obtained; a portion of the sulphur distils over uncombined into the
vessel _b_.
[Illustration: FIG. 1.]
The crude bisulphide of carbon contains about twelve per cent of
sulphur and other combinations in solution and is redistilled at
exactly 48° C. (118.4° F.) in a steam-heated apparatus with a long exit
tube cooled with ice below and water above. In order to obtain the
bisulphide of carbon absolutely pure, which is essential to render it
suitable for extraction, it is again distilled at the same temperature,
with the addition of two per cent of palm oil. As the vapors of
bisulphide of carbon are injurious to the organism, the vessels
containing it must always be kept well closed.
B. Chemical Products used for the Preparation of Perfumes.
Among all the substances belonging under this head, there is one
which plays a prominent part in the manufacture of most perfumes. In
handkerchief perfumes it is one of the most important substances, as
it forms not only the greatest bulk, but the perfection of the perfume
depends upon its quality. This substance is—
ALCOHOL,
also called spirit of wine; French, esprit de vin; the well-known
combustible liquid formed by the alcoholic fermentation of sugar,
which is made on a large scale in extensive distilleries. Alcohol is a
thin, mobile liquid with an aromatic odor. The usual “strong” alcohol
of the market contains about ninety-four per cent of absolute alcohol
by volume. This has a specific gravity of 0·820. Its boiling-point is
78·2° C. (172·40 F.), and it congeals at a very low temperature, below
-100° C. Alcohol possesses great solvent power for resins, balsams, and
essential oils.
These properties, however, belong only to the commercial stronger or
so-called “druggists’ alcohol,” and more particularly to a very pure
quality of it, as free as possible from fusel-oil compounds, known as
cologne spirit. As absolute alcohol is also necessary for the purposes
of perfumery, we shall briefly describe its preparation.
In order to make absolute alcohol, sulphate of copper is heated in a
retort until it has changed into a white powder. After the powder has
cooled in the covered retort, it is at once introduced into a large
glass bottle; over it is poured the strongest obtainable alcohol (96%
Tralles) which must be free from fusel oil; then the bottle is closed
air-tight and repeatedly shaken. The sulphate of copper which has lost
its water of crystallization by the heat reabsorbs it from the alcohol
and again becomes blue and crystalline. Generally four pounds of
sulphate of copper are used for ten quarts of alcohol; when white burnt
sulphate of copper after long contact with alcohol still remains white,
the alcohol is proved to be practically anhydrous (it may still contain
about two per cent of water).
Larger quantities of absolute alcohol are made in a copper still
containing fused anhydrous chloride of calcium in small pieces. The
apparatus is closed and alcohol of 94 to 95% is poured in through a
tubulure. The mixture often grows so warm that the alcohol begins to
pass over, so that but little heat need be applied to make the absolute
alcohol distil over.
Absolute alcohol obtained in this way—for by repeated distillation
we get at most an alcohol of 96%—abstracts water from the air with
avidity; hence it must be preserved in air-tight vessels which should
contain a small amount of anhydrous sulphate of copper.
[Illustration: FIG. 2.]
Strong commercial alcohol contains varying amounts of water—from four
to twenty parts by volume (96 to 80% alcohol); at the present time,
however, it is always customary for dealers in this country to supply
the officinal alcohol of 94%, when “strong alcohol” is called for.
Its strength is measured by an areometer which sinks in proportion to
the purity of the alcohol; the alcoholometer of Tralles or volumeter
shows at once on its scale how many parts by volume of absolute
alcohol (volume per cent) are contained in 100 volumes of alcohol. The
adjoining figure (Fig. 2) shows Tralles’ alcoholometer, with the vessel
in which the test is made. The readings of the instrument, however,
are correct only at a temperature of 15·6° C. (60° F.), the so-called
normal temperature; at a higher or lower point they must be corrected
according to the tables appended.
At temperatures below the normal, the amount of alcohol is greater than
the areometer indicates, hence a percentage must be added; at higher
temperatures a percentage must be deducted.
TABLES FOR FINDING THE TRUE PERCENTAGE BY VOLUME, AT THE NORMAL
TEMPERATURE OF 60° F., OF ALCOHOL OF ANY STRENGTH, WHEN TESTED AT
TEMPERATURES BELOW OR ABOVE 60° F.
TABLE I.—FOR TEMPERATURES UNDER 60° F.
————————+———————————--+
Per cent| Number |
of |of F. Degrees|
Alcohol| Requiring |
by | ADDITION of |
Volume. | one to |
| Percentage. |
————————+———————————--+
21 | 5·4 |
22 | 5·175 |
23 | 4·725 |
24 | 4·5 |
25 | 4·5 |
26 | 4·5 |
27 | 4·5 |
28 | 4·275 |
29 | 4·275 |
30 | 4·275 |
31 | 4·275 |
32 | 4·275 |
33 | 4·275 |
34 | 4·275 |
35 | 4·5 |
36 | 4·5 |
37 | 4·5 |
38 | 4·5 |
39 | 4·5 |
40 | 4·5 |
41 | 4·725 |
42 | 4·725 |
43 | 4·725 |
44 | 4·725 |
45 | 4·95 |
46 | 4·95 |
47 | 4·95 |
48 | 4·95 |
49 | 4·95 |
50 | 5·175 |
51 | 5·175 |
52 | 5·175 |
53 | 5·175 |
54 | 5·175 |
55 | 5·175 |
56 | 5·175 |
57 | 5·4 |
58 | 5·4 |
59 | 5·4 |
60 | 5·4 |
61 | 5·4 |
62 | 5·4 |
63 | 5·625 |
64 | 5·625 |
65 | 5·625 |
66 | 5·625 |
67 | 5·625 |
68 | 5·85 |
69 | 5·85 |
70 | 5·85 |
71 | 5·85 |
72 | 5·85 |
73 | 5·85 |
74 | 6·075 |
75 | 6·075 |
76 | 6·075 |
77 | 6·075 |
78 | 6·3 |
79 | 6·3 |
80 | 6·3 |
81 | 6·525 |
82 | 6·525 |
83 | 6·75 |
84 | 6·75 |
85 | 6·75 |
86 | 6·75 |
87 | 6·975 |
88 | 7·2 |
89 | 7·425 |
90 | 7·65 |
91 | 7·875 |
92 | 8·1 |
93 | 8·325 |
94 | 8·775 |
95 | 9· |
96 | 9·45 |
97 | 10·125 |
————————+———————————--+
EXPLANATION.—Supposing an alcohol should be found to contain 40 per
cent of absolute alcohol by Tralles’ alcoholometer at 45° F. The
difference between 45 and 60° F. is 15. Opposite to 40 will be found
the figure 4·5. For every 4·5 degrees F. below 60° there must be added
1 to the alcoholic percentage. Hence for 15 degrees there must be
added 3.3 degrees. The alcoholic percentage, by volume, therefore, is
43·3 per cent.
TABLE II.—FOR TEMPERATURES ABOVE 60° F.
————————+————————-———-
Per cent| Number
of |of F. Degrees
Alcohol | Requiring
by |SUBTRACTION
Volume. | of one from
| Percentage.
————————+——————-—————-
21 | 5·85
22 | 5·625
23 | 5·4
24 | 5·175
25 | 4·95
26 | 4·95
27 | 4·725
28 | 4·725
29 | 4·5
30 | 4·5
31 | 4·5
32 | 4·5
33 | 4·5
34 | 4·5
35 | 4·5
36 | 4·5
37 | 4·5
38 | 4·5
39 | 4·5
40 | 4·5
41 | 4·5
42 | 4·5
43 | 4·5
44 | 4·5
45 | 4·5
46 | 4·5
47 | 4·725
48 | 4·725
49 | 4·725
50 | 4·725
51 | 4·725
52 | 4·725
53 | 4·95
54 | 4·95
55 | 4·95
56 | 5·175
57 | 5·175
58 | 5·175
59 | 5·175
60 | 5·175
61 | 5·175
62 | 5·175
63 | 5·175
64 | 5·175
65 | 5·175
66 | 5·4
67 | 5·4
68 | 5·4
69 | 5·625
70 | 5·625
71 | 5·625
72 | 5·625
73 | 5·625
74 | 5·625
75 | 5·85
76 | 5·85
77 | 5·85
78 | 5·85
79 | 6·075
80 | 6·075
81 | 6·075
82 | 6·075
83 | 6·3
84 | 6·3
85 | 6·3
86 | 6·525
87 | 6·525
88 | 6·525
89 | 6·75
90 | 6·975
91 | 6·975
92 | 7·425
93 | 7·425
94 | 7·65
95 | 7·65
96 | 8·1
97 | 8·1
98 | 8·325
99 | 9·45
100 | 9·9
————————+——————————--
EXPLANATION.—In this case, the same calculation is performed as
directed under Table I., except that the correction is to be
_deducted_ instead of added.
Aside from the water present in it, commercial alcohol is never
pure, but always contains small quantities, at times mere traces,
of substances having a peculiar, sometimes pleasant, sometimes
disagreeable, but invariably intense odor, which are known as fusel
oils. The variety of fusel oil differs with the raw material from which
the alcohol was made; there is a potato fusel oil (chemically amyl
alcohol), a corn fusel oil, a beet fusel oil, wine fusel oil (œnanthic
ether), etc. Fusel oils, being themselves odorous substances, exert an
influence on the fragrance of the perfume; hence it is a general rule
in perfumery to use only alcohol free from fusel oil; that is, such
from which the fusel oil has been extracted as far as possible by means
of fresh charcoal. So-called “Cologne Spirit” of the best quality is,
as a rule, practically free from it.
Strange to say, some essential oils or aromatic substances in general,
develop their finest odors only when the perfumes are prepared with an
alcohol from a certain source. While the charcoal treatment removes
almost all the fusel oil, the remaining traces suffice to act as
odorous substances in the true sense of the term and to produce with
other aromatic bodies a harmony of the odor which can never be reached
by the use of another variety of alcohol. To give but a single instance
we may state that all the citron odors known in perfumery develop the
finest aroma only when dissolved in alcohol made from wine and the
solution is then distilled. The world-renowned eau de Cologne is made
in this way; the other aromatic substances contained in it are added to
the distillate from the spirit of wine and the citron oils; any cologne
made in another manner or with another alcohol has a less fine odor.
While the citron odors require true spirit of wine for the development
of their full aroma, other scents require beet or corn alcohol to bring
out their best odor. Jasmine, tuberose, orange flowers, violet, etc.,
and all animal odors (ambergris, musk, and civet) belong to the latter
class. For this remarkable and to the perfumer most important fact we
know no other explanation than that traces of fusel oils present even
in rectified alcohol take part in the general impression made on the
olfactory nerves, acting as true aromatic substances.
Cologne spirit is expensive, but this should not be a reason for
accepting a cheaper grade, with which it would be absolutely impossible
to make really fine perfumes.
Alcohol is also generally used for the direct extraction of odorous
substances from plants, as will be seen in the description of the
processes employed in the preparation of the so-called essences or
extracts. For these purposes, too, the best cologne spirit only
should be used, that is, alcohol which has been freed from fusel oil
and redistilled, for in no other way can the aromatic substances be
obtained in the greatest possible purity. And this is indispensable
for the preparation of really fine perfumes, for we do not hesitate
to say that French and English perfumes have acquired their deserved
reputation mainly through the great care exercised in the selection of
their raw materials, and especially of the alcohol used for extraction.
ALLOXAN.
This preparation, which is used in making a fine skin cosmetic, is
manufactured in chemical laboratories from uric acid heated with nitric
acid. Alloxan is a crystalline colorless body which has the property
of gradually producing a red tint on the skin and finds employment for
this reason.
AMMONIA.
Ammonia is a gas formed by the decomposition of nitrogenous substances,
but chiefly obtained, on a large scale, from the so-called “gas
liquor” of gas works. By itself it develops a very disagreeable odor
and stimulates the lachrymal glands to secretion—a fact which can
be verified in any stable. A solution of the gas (water of ammonia;
liquor ammoniæ) possesses the same properties. In perfumery ammonia is
never used alone, but only in combination with other odors, namely,
in the manufacture of smelling salts (French: sels volatils; German:
Riechsalze), which are much in favor in England and in this country.
For the purposes of the perfumer, the greater part of the commercial
ammonia is unsuitable owing to its tarry odor. Pure ammonia is best
prepared by heating equal parts of quicklime and powdered sal-ammoniac
in a retort, and conducting the generated gas into water which
dissolves it with avidity, one quart of water dissolving more than
seven hundred quarts of ammonia gas.
CARBONATE OF AMMONIA,
a combination of ammonia with carbonic acid, occurs in commerce in
large transparent lumps, often covered with a white dust of bicarbonate
of ammonia, which in the air continually develop ammonia and therefore
always smell of it. This commercial product is, as a rule, sufficiently
pure to be used in perfumery; as to its application the same remarks
apply as were made under the head of ammonia.
OIL OF BITTER ALMONDS (OLEUM AMYGDALÆ AMARÆ).
This is made from bitter almonds, previously deprived of fatty oil by
pressure, which are mixed with an equal weight of water and set in a
warm place. The amygdalin undergoes decomposition into sugar, hydrogen
cyanide, and benzoyl hydride or oil of bitter almonds. After one or two
days the mass is distilled; the distillate being a colorless liquid,
containing, besides oil of bitter almonds, hydrogen cyanide or prussic
acid, one of the most virulent poisons, from which it must be freed.
This is done by shaking the liquid repeatedly with dilute solution of
potassa, followed by agitation with water. Pure oil of bitter almonds
is not poisonous, but has a very strong narcotic odor of bitter
almonds, which, however, becomes most marked when largely diluted with
water.
BENZOIC ACID (ACIDUM BENZOICUM).
This acid, contained in benzoin, is made also synthetically from other
materials, in chemical laboratories. When pure it forms needle-shaped
crystals having a silky gloss; they have a peculiar acrid taste, but no
odor. Synthetic benzoic acid is worthless to the perfumer; in his art
he can use only a benzoic acid made from gum benzoin by sublimation,
because it contains a very aromatic essential oil for which the acid
is merely the vehicle and which can also be employed alone.
As this sublimed benzoic acid is often adulterated with the artificial,
we advise the manufacturer of perfumery to make his own benzoic acid
according to the following directions.
_The Manufacture of Sublimed Benzoic Acid._
About four pounds of benzoin B of best quality is broken into small
pieces and placed in a small copper boiler K (Fig. 3); over its entire
surface is pasted white blotting paper L, and to this is pasted a cone
of strong paper which must surround the edge of the boiler. The cone
ends above in a paper tube R, about five feet long and an inch wide.
The copper boiler is placed in a large clay pot T (a flower pot) and
surrounded on all sides with fine sand. The clay pot is heated from
without by a charcoal fire. After the pot has remained about half an
hour on the fire, the latter is fanned to its utmost and kept at this
point for thirty minutes. The heat volatilizes the benzoic acid, the
above-mentioned essential oil, and some tarry substances of a brown
color. The latter are arrested by the filter paper, while the benzoic
acid is deposited on the cone and in the tube, in the form of delicate
glossy needles which are very fragrant owing to the essential oil.
The largest yield of benzoic acid is obtained when the temperature is
raised very gradually, until finally nothing remains in the copper
boiler but a brown, almost carbonized mass of a blistered appearance.
[Illustration: FIG. 3.]
BORAX (SODII BORAS)
is used in some preparations. Borax forms colorless crystals which
slightly effloresce in dry air and hence must be preserved in tightly
closed vessels. Reddish tinted crystals are contaminated with oxide of
iron and should be rejected.
PERMANGANATE OF POTASSIUM (POTASSI PERMANGANAS)
is a salt formed by fusing a mixture of manganese dioxide, potassa, and
potassium chlorate, extracting the product with water, and evaporating
the solution to crystallization; the salt is obtained in small dark
violet, almost black crystals which dissolve in sixteen parts of water
to which they impart a beautiful violet color. By contact with organic
substances, or others easily oxidized, the solution changes its color
into green and finally is decolorized, precipitating a brown powder.
Owing to this change of color the salt has been called chameleon
mineral. As its preparation requires considerable dexterity, it is
preferable to buy it from reputable houses, rather than to make it. It
is used in the manufacture of mouth washes and hair dyes. The solution
of the salt causes brown stains on linen and the skin; they can be
removed only if the spots are immediately washed with hydrochloric,
oxalic, sulphuric, or another acid.
ACETIC ACID (ACIDUM ACETICUM).
Much confusion exists in the literature regarding the strength of
acetic acid when merely called by this name. It is safe to assume
that, in each country, the term applies to the acid officinal in
its national pharmacopœia as “Acidum Aceticum.” Thus the Austrian
and German pharmacopœias understand by it an acid containing 96% of
absolute acetic acid, which is practically identical with what is
known as glacial acetic acid. The latter is, in some pharmacopœias,
distinguished by a special name: acidum aceticum glaciale, U.S. P.;
acide acétique crystallisable, French Pharm.—In the present work, the
author always intended the strong acid of the Austrian pharmacopœia
to be understood when no other strength was designated. Like alcohol,
strong acetic acid dissolves essential oils and is used in the
manufacture of various toilet vinegars and washes. Acetic acid is made
in chemical laboratories by distillation of acetate of sodium with
sulphuric acid, or more commonly from wood vinegar. The buyer should
always satisfy himself that the product is free from an empyreumatic
odor which clings tenaciously to an insufficiently purified sample.
FATS.
Fats find extensive application in perfumery, in the preparation of
the so-called huiles antiques, pomades, and many other cosmetics. They
should be enumerated among the chemical products used in perfumery
because they can never be employed in their commercial form, but
must undergo some process of purification, which is effected less by
mechanical than by chemical means. Commercial fats usually contain
remnants of the animal or vegetable body from which they are derived:
particles of blood and membranes occur frequently in animal fats;
cell bodies and vegetable albumin in vegetable fats. Besides these
mechanical impurities, fats, especially if old, sometimes contain
small amounts of free fatty acids which suffice to impart to them the
objectionable odor and taste peculiar to every rancid fat. While some
fats, such as bear’s grease, butter of cacao, oil of sesame, and some
others, remain free from rancidity for a long time, others undergo this
change very rapidly; in fact, we may say that every fat which shows
the slightest odor should be called rancid, for pure fat is absolutely
odorless.
We shall here briefly describe the process employed in the fat industry
and by perfumers for the purification of fats. Animal fat, such as
lard, suet, bear’s grease, etc., as well as cocoanut and palm oils,
are introduced into a large iron boiler containing dilute soda lye
(not exceeding one per cent of caustic soda), and the lye is heated
to boiling. In the boiler is a small pump terminating above in a
curved tube having a rose of a watering-pot at the end. The pump is so
arranged as to raise lye and melted fat at the same time and to return
the fluid into the boiler in a fine spray. After the fat is melted, the
solid matters floating on top are skimmed off with a perforated spoon,
and then the pump is operated for about fifteen minutes. The contained
shreds of membrane and similar substances are completely dissolved by
the soda lye, the free fatty acids are perfectly combined, and the
fat is at the same time decolorized. After cooling, it floats on the
surface of the lye as a colorless and odorless fluid; it is ladled
off and poured into tall tapering vessels which are well closed and
preserved in cool cellars. Contact with the air, especially at higher
temperatures, causes rancidity of the fat. For every twenty pounds of
fat twenty quarts of lye are used.
According to another process the fat is purified by being heated with
alum and table salt; or every twenty-five pounds of fat, one ounce of
alum and two ounces of salt are dissolved in five gallons of water.
The scum is carefully skimmed from the surface of the melted fat, and,
after it has solidified, the fat is washed with water until the latter
escapes perfectly tasteless and odorless.
The washing is a very complicated and tedious piece of work. Operating
on a small scale, a slightly inclined marble slab is taken, upon which
a thin stream of water is constantly falling from a tube arranged above
it. The fat is placed on the slab in small quantities (not over two
pounds) and ground with a muller, like oil colors, under a constant
flow of water. Owing to the expense of hand labor, it is advisable to
use a so-called vertical mill or chaser. This consists of a level,
circular, horizontal marble slab, bearing a central, easily movable
axis with a crosspiece upon which two, likewise vertical, cylindrical
marble plates turn like wheels in a circle on the horizontal marble
plate. The fat is placed on the latter and continually irrigated with
water; behind every chaser is applied a marble plate with a blade which
nearly touches the chasers and returns the fat displaced laterally,
under the chasers. The axis around which the chasers run is kept moving
by any available power, and the laborer has nothing to do but to
replace the washed fat with crude.
Liquid fats are purified as follows:
The oil is intimately mixed with one per cent of sulphuric acid. The
mixture assumes a black color, the vegetable mucilage present in the
oil becoming carbonized. After several days’ rest the oil becomes clear
and floats on the surface of the sulphuric acid which has assumed a
black color from the presence of finely divided carbon. The oil is
decanted and treated, in the manner above stated for solid fats, with
caustic soda lye. Heating can be dispensed with if the pumping is
continued for a longer time.
Benzoin and benzoic acid have the property of counteracting the
tendency of fats to become rancid; it is advisable, therefore, to mix
intimately with the completely washed fat a small amount of benzoic
acid, at most one-one-thousandth part by weight.
The best way of preserving fats is by salicylic acid. This is added
to solid fats while they are in a melted state; if oils, the acid is
poured in and the bottle vigorously shaken. If the oil is in casks,
a small bag filled with salicylic acid is hung into it from the
bung-hole. The acid dissolves in the oil and is disseminated through it
and thus effects its preservation. One-one-thousandth part by weight of
the fat or oil is said to be more than sufficient to keep it perfectly
fresh for years.
Fats differ largely in their physical properties—for instance, in
their appearance, melting-point, firmness, etc. As we shall return to
this subject in connection with the manufacture of some perfumes, it is
enough here to state briefly that by the addition of spermaceti, wax,
paraffin, etc., fats are made more transparent and firmer—a matter of
importance for some cosmetic preparations.
CHINESE GELATIN.
This substance, derived from several algæ, species of Eucheuma,
indigenous to the Chinese sea, and identical with Japanese agar-agar,
on being boiled with two hundred parts of water has the property of
forming a colorless solution which solidifies on cooling. Owing to this
property the addition of a small quantity of Chinese gelatin (0·1-0·2%)
is an excellent means for imparting to certain pomades and ointments
great transparency and firmness.
FRUIT ETHERS
are liquids which possess an agreeable, refreshing odor resembling
that of some fruits. For this reason they are used in confectionery,
in the manufacture of liqueurs, and also in many ways in perfumery.
Chemically, fruit ethers are combinations of an organic acid—acetic,
butyric, valerianic, etc.—with a so-called alcohol radicle such as
ethyl and amyl. Their manufacture is connected with many difficulties
and is but rarely attempted by perfumers, especially as these products
are made a specialty in some chemical laboratories and are furnished at
very low prices and of excellent quality. In perfumery the following
fruit ethers are particularly employed.
ACETIC ETHER,
prepared by the distillation of acetate of sodium with alcohol and
sulphuric acid, is a colorless liquid having an odor of fermenting
apple juice, with a boiling-point at 74° C. (155° F.).
PINE-APPLE ETHER
(ether or huile d’ananas) is made by the saponification of butter
with solution of potassa, distillation of the soap with alcohol
and sulphuric acid, and rectification of the distillate. It is
an inflammable liquid with an intense odor of pine-apple; its
boiling-point is 119° C. (246° F.). It is not generally used pure, as
its odor needs some correction. This is accomplished by the addition of
a little valerianate of amyl, and chloroform. Also in other ways.
APPLE ETHER,
prepared by distillation from valerianate of sodium with alcohol and
sulphuric acid, and the subsequent addition of certain correctives (see
below).
PEAR ETHER,
also called pear oil, chiefly valerianate of amyl oxide, can be
obtained in large quantities from a by-product in the manufacture of
potato spirit, namely, amyl alcohol, which is carefully heated in a
still with bichromate of potassium and sulphuric acid. The product thus
obtained has a very pleasant odor of fine pears and boils at 196° C.
(385° F.). But the commercial “pear-essence” is a more complex body
(see following table).
NITROUS ETHER
is a very volatile liquid boiling at 16° C. (61° F.), which is obtained
by distillation of strong alcohol with concentrated nitric acid and
rectification of the distillate; it is less used in perfumery than the
other fruit ethers.
Fruit ethers, owing to their low price and great strength, are
frequently employed in the manufacture of cheap perfumery, in place of
essential oils, but more largely for scenting soap.
The so-called raspberry and strawberry ethers consist of mixtures of
acetic, pine-apple, apple, and other ethers (see following table),
which, combined in certain proportions, really manifest an odor nearly
akin to those of the fruits after which they are named.
FRUIT ETHERS (FRUIT ESSENCES).
TABLE SHOWING THE INGREDIENTS USUALLY EMPLOYED FOR PREPARING ARTIFICIAL
FRUIT ETHERS (FRUIT ESSENCES).
A = Peach.
B = Apricot.
C = Plum.
D = Cherry.
E = Black Cherry.
F = Lemon.
G = Pear.
H = Orange.
I = Apple.
J = Grape.
K = Gooseberry.
L = Raspberry.
M = Strawberry.
N = Melon.
O = Pine-apple.
————————————————————————————+—-—+—-—+—-—+—-—+—-—+—-—+—-—+—-—+—-—+
| A | B | C | D | E | F | G | H | I |
————————————————————————————+—-—+—-—+—-—+—-—+—-—+—-—+—-—+—-—+—-—+
Glycerin | 5 | 4 | 8 | 3 |.. | 5 |10 |10 | 4 |
Chloroform |.. | 1 |.. |.. |.. | 1 |.. | 2 | 1 |
Nitrous ether |.. |.. |.. |.. |.. | 1 |.. |.. | 1 |
Aldehyde | 2 |.. | 5 |.. |.. | 2 |.. | 2 | 2 |
Acetate of ethyl | 5 |.. | 5 | 5 |10 |10 | 5 | 5 | 1 |
Formate of ethyl | 5 |.. | 1 |.. |.. |.. |.. | 1 |.. |
Butyrate of ethyl | 5 |10 | 2 |.. |.. |.. |.. | 1 |.. |
Valerianate of ethyl | 5 | 5 |.. |.. |.. |.. |.. |.. |.. |
Benzoate of ethyl |.. |.. |.. | 5 | 5 |.. |.. | 1 |.. |
Œnanthate of ethyl | 5 | 1 | 4 | 1 | 2 |.. |.. |.. |.. |
Salicylate of methyl | 2 | 2 |.. |.. |.. |.. |.. | 1 |.. |
Sebacic acid | 1 |.. |.. |.. |.. |.. |10 |.. |.. |
Acetate of amyl |.. |.. |.. |.. |.. |.. |.. |10 |.. |
Butyrate of amyl |.. | 1 |.. |.. |.. |10 |.. |.. |10 |
Valerianate of amyl |.. |.. |.. |.. |.. |.. |.. |.. |.. |
Essence of orange |.. |.. |.. |.. |.. |10 |.. |10 |.. |
Alcohol, {Tartaric acid|.. |.. |.. |.. | 1 |.. |.. | 1 | 1 |
solutions {Oxalic acid |.. | 1 |.. |.. |.. | 1 |.. |.. |.. |
saturated in{Succinic acid|.. |.. |.. | 1 | 2 |.. |.. |.. |.. |
the cold of {Benzoic acid |.. |.. |.. |.. |.. |.. |.. |.. |.. |
————————————————————————————+—-—+—-—+—-—+—-—+—-—+—-—+—-—+—-—+—-—+
————————————————————————————+—-—+—-—+—-—+—-—+—-—+—-—+
| J | K | L | M | N | O |
————————————————————————————+—-—+—-—+—-—+—-—+—-—+—-—+
Glycerin |10 |.. | 4 | 2 | 3 | 3 |
Chloroform | 2 |.. |.. |.. |.. | 1 |
Nitrous ether |.. |.. | 1 | 1 |.. |.. |
Aldehyde | 2 | 1 | 1 |.. | 2 | 1 |
Acetate of ethyl |.. | 5 | 5 | 5 |.. |.. |
Formate of ethyl | 2 |.. | 1 | 1 | 1 |.. |
Butyrate of ethyl |.. |.. | 1 | 5 | 4 | 5 |
Valerianate of ethyl |.. |.. |.. |.. | 5 |.. |
Benzoate of ethyl |.. | 1 | 1 |.. |.. |.. |
Œnanthate of ethyl |10 | 1 | 1 |.. |.. |.. |
Salicylate of methyl | 1 |.. | 1 | 1 |.. |.. |
Sebacic acid |.. |.. | 1 |.. |10 |.. |
Acetate of amyl |.. |.. | 1 | 3 |.. |10 |
Butyrate of amyl |.. |.. |.. | 2 |.. |.. |
Valerianate of amyl |.. |.. |.. |.. |.. |.. |
Essence of orange |.. | 5 | 5 |.. |.. |.. |
Alcohol, {Tartaric acid| 5 |.. |.. |.. |.. |.. |
solutions {Oxalic acid |.. | 1 | 1 |.. |.. |.. |
saturated in{Succinic acid| 3 | 1 |.. |.. |.. |.. |
the cold of {Benzoic acid |.. |.. | 1 |.. |.. |.. |
————————————————————————————+—-—+—-—+—-—+—-—+—-—+—-—+
GLYCERIN.
This substance, which may be called a true cosmetic in itself, as it
possesses marked solvent power for cutaneous coloring matters and at
the same time imparts to the skin delicacy and flexibility, is at
present to be had commercially in great purity. Pure glycerin is a
brilliant, colorless, and odorless substance of the consistence of a
thick syrup, which mixes with water and alcohol in all proportions and
has a slightly warm but very sweet taste. It readily absorbs aromatic
substances and is used in many valued toilet articles in combination
with fats and perfumes. Recently we have succeeded in using glycerin
most successfully for the extraction of aromatic substances.
OIL OF MIRBANE,
also called artificial oil of bitter almonds, nitrobenzol, and essence
of mirbane. This substance, which is now largely used in perfumery
and soap manufacture, is obtained by the action of fuming nitric acid
on benzol. The mixture becomes hot and emits masses of brown vapors,
and there is formed a yellow oily body which is washed with water and
soda solution until the washings escape colorless. Pure nitrobenzol is
not soluble in water, but in alcohol or ether, boils at 213° C. (415°
F.), and congeals at-5 to 6° C. (21-23° F.). Its spec. grav. is 1·2
or a little over. Any oil of mirbane having a lower specific gravity
than 1·2 at 15° C. (59° F.) is spurious, most likely nitrotoluol.
Its odor greatly resembles that of oil of bitter almonds, but can be
clearly differentiated from it on comparison. Care must be taken in
inhaling the vapor when undiluted, as it is poisonous. By distillation
nitrobenzol can be obtained quite colorless, and in this form is
often used for the adulteration of genuine oil of bitter almonds.
This adulteration, however, can be easily demonstrated by heating for
a short time with an alcoholic solution of a caustic alkali which
separates from nitrobenzol a brown resinous substance, while true oil
of bitter almonds loses its odor and changes into benzoic acid which
unites with the alkali.
PARAFFIN.
This substance is one of the products of the distillation of petroleum,
coal, peat, and other carbonaceous sources. It is a crystalline,
brittle body, closely resembling wax in appearance and melting between
51 and 60° C. (124 and 140° F.). Paraffin, which is now made on a large
scale for the manufacture of candles, is very useful in perfumery as
a partial substitute for the much more expensive wax or spermaceti,
over which it has the advantage, besides its cheapness, that it imparts
to the articles great transparency—a quality which is valued highly
in fine perfumeries. The addition of some paraffin to pomades renders
them more consistent and counteracts their tendency to become rancid.
Distilled paraffin always has a crystalline form, differing from
the paraffin-like residues left after the distillation of petroleum
(so-called vaselins, etc., see below) which are always amorphous.
PYROGALLIC ACID
appears in commerce as a white crystalline powder, made by heating
gallic acid to 200-210° C. (392-410° F.). With iron salts, pyrogallic
acid forms bluish-black combinations and precipitates the metal from
silver solutions as a velvety-black powder. On account of these
properties pyrogallic acid is used in perfumery as a constituent of
some hair dyes.
SULPHIDE OF POTASSIUM,
liver of sulphur, hepar sulphuris, potassii sulphuretum, the
pentasulphide of potassium, is obtained by fusing together potash and
sulphur, in the shape of a leather-brown mass which is soluble in water
and on exposure to the air is gradually decomposed with the development
of the offensive sulphuretted hydrogen gas; hence it should be
preserved in well-closed vessels. An aqueous solution of this substance
forms with lead or silver salts a black precipitate of sulphide of lead
or silver, and is used for some hair dyes.
STARCH FLOUR
(amylum) is prepared from various vegetables such as potatoes, rice,
arrowroot, sago, etc., and when pure appears as an insoluble white
powder which the microscope shows to be grains consisting of many
superimposed layers. In commerce the price of the different varieties
of starch fluctuates greatly; in perfumery well-cleansed potato starch
can very well be used for dusting powders, and the so-called poudre de
riz; in this country, corn starch is preferable.
VANILLIN,
that is, the body to which vanilla owes its fragrance, is now made
artificially and can be used in place of vanilla for soaps and pomades.
VASELIN.
In the distillation of petroleum there remain in the still as a residue
large quantities of a substance which when purified is colorless and,
according to the nature of the petroleum, at ordinary temperatures has
either the consistence of lard, melting under the heat of the hand, or
forms an oily liquid. In perfumery vaselin can be used like fat or oil,
over which it has the advantage in that it always remains odorless and
free from acid; hence it is very appropriate for the manufacture of
pomades. The market affords numerous varieties of this substance, under
different names: vaselin (oil and solid), albolene (oil and solid),
cosmolin, etc., etc.
SPERMACETI
is a substance found in the skull cavities of several whales and
dolphins. In its properties it stands midway between beeswax, paraffin,
and firm fats. In the living animal spermaceti is fluid, but after its
death it congeals to a white crystalline mass of a fatty lustre, which
melts at 40° C. (104° F.), and is frequently used for fine candles as
well as for other articles.
WAX
(Cera alba), the well-known product of the bee; in perfumery only
bleached (white) wax is employed. In recent years Japanese wax
has appeared in commerce; this is of vegetable origin, but in its
properties resembles beeswax.
SUBNITRATE OF BISMUTH,
bismuth white, pearl white, bismuthi subnitras, blanc de bismuth,
blanc de perles, the basic nitrate of bismuth, the chief ingredient
of many skin cosmetics, is prepared by dissolving metallic bismuth in
moderately strong nitric acid, and pouring the solution into a large
quantity of water, whereupon the subnitrate is precipitated.
The precipitated powder is collected on a funnel and washed with pure
water until the wash water no longer changes blue tincture of litmus to
red. The bismuth white is dried and preserved in well-closed vessels,
since in the air it gradually assumes a yellowish color; for any
sulphuretted hydrogen present in the air is greedily absorbed by this
salt, and the resulting combination with sulphur has a black color.
OXIDE OF TIN
is obtained by treating metallic tin with fuming nitric acid, adding
the solution to a large quantity of water, and washing the product,
which forms a white insoluble powder used cosmetically for polishing
the finger nails.
* * * * *
Besides the chemical products here enumerated, some others find
application in perfumery; we shall describe their properties in
connection with the articles into which they enter. In this connection
mention may be made of the fact that more and more aromatic substances
are now made artificially which were formerly obtained with difficulty
from plants. Besides vanillin mentioned above, cumarin, oil of
wintergreen, and some other products are prepared artificially.
Heliotropin and nerolin are artificially prepared substances,
possessing an odor resembling that of heliotrope and oil of neroli,
respectively, but not identical chemically with the natural odorous
substance. Artificial musk (Baur’s), is playing a rôle at present, but
is not identical with the natural substance.
C. The Colors used in Perfumery.
Some articles are colored intentionally; this remark applies
particularly to some soaps which not rarely are stained to correspond
to the color of the flower whose odor they bear; for instance, violet
soap. Some articles again are used only on account of their color;
for instance, paints, hair and whisker dyes. As we shall discuss this
subject at greater length in connection with these toilet articles, we
merely state here that nowadays every manufacturer can choose between a
large number of dyes of any color, all of which are innoxious; hence no
perfumer should under any circumstances use poisonous colors. This is
a matter of importance with substances intended for immediate contact
with the human body such as paints, lip salves, soaps, etc. All of
these colors will be described hereafter.