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.