concerned with somewhat more complex or somewhat more refined sexual odors; they are not specifically different from the human odors and they mingle with them harmoniously. Popular language bears witness to the truth of this statement, and the normal and abnormal human odors, as we have already seen, are constantly compared to artificial, animal, and plant odors, to chloroform, to musk, to violet, to mention only those similitudes which seem to occur most frequently. The methods now employed for obtaining the perfumes universally used in civilized lands are three: (1) the extraction of odoriferous compounds from the neutral products in which they occur; (2) the artificial preparation of naturally occurring odoriferous compounds by synthetic processes; (3) the manufacture of materials which yield odors resembling those of pleasant smelling natural objects. (See, e.g., "Natural and Artificial Perfumes," _Nature_, December 27, 1900.) The essential principles of most of our perfumes belong to the complex class of organic compounds known as terpenes. During recent years a number of the essential elements of natural perfumes have been studied, in many cases the methods of preparing them artificially discovered, and they are largely replacing the use of natural perfumes not only for soaps, etc., but for scent essences, though it appears to be very difficult to imitate exactly the delicate fragrance achieved by Nature. Artificial musk was discovered accidentally by Bauer when studying the butyltoluenes contained in a resin extractive. Vanillin, the odoriferous principle of the vanilla bean, is an aldehyde which was first artificially prepared by Tiemann and Haarmann in 1874 by oxidizing coniferin, a glucoside contained in the sap of various coniferæ, but it now appears to be usually manufactured from eugenol, a phenol contained in oil of cloves. Piperonal, an aldehyde closely allied to vanillin, is used in perfumery under the name of heliotropin and is prepared from oil of sassafras and oil of camphor. Cumarine, the material to which tonka bean, sweet woodruff, and new-mown hay owe their characteristic odors, was synthetically prepared by W.H. Parkin in 1868 by heating sodiosalicylic aldehyde with acetic anhydride, though now more cheaply prepared from an herb growing in Florida. Irone, which has the perfume of violets, was isolated in 1893 from a ketone contained in orris-root; and ionone, another ketone which has a very closely similar odor of fresh violets and was isolated after some years' further work, is largely used in the preparation of violet perfume. Irone and ionone are closely similar in composition to oil of turpentine which when taken into the body is partly converted into perfume and gives a strong odor of violets to the urine. "Little has yet been accomplished toward