PREPARATIONS FOR THE CARE OF THE SKIN.
GLYCERIN.
Pure glycerin is a substance that has a powerful beautifying effect on
the skin, by rendering it white, supple, soft, and glossy; no other
remedy will clear a sun-burnt skin in so short a time as glycerin.
An excellent wash may be made by the perfumer by mixing equal parts
of thick, colorless glycerin and orange-flower water (or some other
aromatic water with fine odor), possibly giving it a rose color by the
addition of a very small amount of fuchsine. Concentrated glycerin must
not be used as a wash, because it abstracts water from the skin and
thereby produces a sensation of heat or burning.
Besides common soap, the so-called emulsions, meals, pastes, vegetable
milks and creams are the best preparations for the care of the skin;
in perfumery they are even preferable to soap in some respects because
they contain not only substances which have a cleansing effect like any
soap, scented or not, but at the same time render the skin clearer,
more transparent, and more supple.
EMULSIONS.
Many perfumers make a definite distinction between two groups
of emulsions which they call respectively “emulsions” and “true
emulsions.” By “emulsions” they mean masses which have the property
of changing on contact with water into a milky fluid or becoming
emulsified; the term “true emulsions” is applied to such preparations
as already contain a sufficient amount of water and therefore have a
milky appearance. Hence the difference between the two preparations
lies in the lesser or greater quantity of water, and is so variable
that we prefer to describe them under one head.
The cause of the milky appearance of the emulsions on coming in contact
with water is that they contain, besides fat, substances which possess
the property of keeping the fat suspended in form of exceedingly minute
droplets which make the entire fluid look like milk. As a glance
through the microscope shows, the milk of animals consists of a clear
fluid in which the divided fat droplets (butter) float; these by their
refractive power make the milk appear white.
While soaps always contain a certain quantity of free alkali, a
substance having active caustic properties, emulsions include very
little if any alkali, and, since they possess the same cleansing power
as soap without its disadvantages with reference to the skin, their
steady use produces a warm youthful complexion, as well as smoothness
and delicacy of the skin.
Glycerin is of special importance in the composition of emulsions.
Besides the above-mentioned property of this substance of keeping
the skin soft and supple, it acts as a true cosmetic by its solvent
power of coloring matters: a skin deeply browned by exposure to the
sun is most rapidly whitened by the use of glycerin alone. Moreover,
glycerin prevents the decomposition of the preparations and keeps them
unchanged for a long time. This quality has a value which should not be
underestimated; for all emulsions are very apt to decompose and become
rancid owing to the finely divided fat they contain. Under ordinary
conditions, only complete protection against light and air can retard
rancidity, which is accompanied by a disagreeable odor not to be masked
by any perfume; an addition of glycerin, which we incorporate in all
emulsions, makes them more permanent owing to the antiseptic property
of this substance.
Recent years, however, have made us acquainted with a substance which
in very minute quantities—one-half of one per cent of the mass to be
preserved by it—prevents decomposition and rancidity of fats. This is
salicylic acid, a chemical product which, being harmless, tasteless,
and odorless, should be employed wherever we wish to guard against
destructive influences exerted by air, fermentation, etc. While
formerly all emulsions were made only in small amounts, just sufficient
for several weeks’ use, salicylic acid enables us to manufacture
larger quantities at once and to keep them without much fear of their
spoiling. However, even the presence of salicylic acid is no guaranty
against deterioration, if other precautions are neglected. The products
should be kept in well-stoppered bottles or vessels, in a cool and
dark place. All substances cannot be preserved by salicylic acid,
and there are certain ferments or fungi which resist the action of
salicylic acid. If chloroform is not objectionable in any of these
preparations—and only so much is necessary as can be held in actual
_solution_ by the liquid, on an average three drops to the ounce—this
preservative is preferable to salicylic acid.
The only fats used in the preparation of emulsions are expressed oil
of almonds, olive oil, and lard. Almond oil is best made by immediate
pressure of the bruised fruits, since fresh almond meal likewise finds
application in perfumery; olive oil and lard must be very carefully
purified. This is done by heating them for one hour with about ten
times the quantity of water containing soap (one per cent of the
quantity of fat to be purified). They are then treated five or six
times with pure warm water until the latter escapes quite neutral. If
the water turns red litmus paper blue, it would indicate the presence
of free alkali (soap); if it turns blue litmus paper red, it would
prove the presence of free fatty acids (rancid fat). Either one of
these substances, especially the latter, would injure the quality
of the product. The fat should be absolutely neutral and have no
influence on either kind of litmus paper; then its quality may be
pronounced perfect.