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.