In this way, of course, the pomade acquires a very large surface and rapidly yields the aromatic substance to the alcohol. The odor of the pomade differs according to the length of time which it has been subjected to the flowers, and on being treated with alcohol furnishes extracts of corresponding strength. This should be borne in mind in the manufacture of perfumes which are intended to be uniform in quality. After two cold and one warm infusion of the pomade, it may be made to yield some more aromatic material by heating it carefully to its exact melting-point, when extract again appears on the surface and can be poured off by gentle inclination of the vessel. In the following pages we give the proportions by weight and measure employed by the most important French, English, and German manufacturers for their pomade extracts or solutions of the essential oils in alcohol. As to the latter we again repeat that it must be over 88 to 90% strength according to Tralles or even stronger, and that it must be absolutely free from any trace of amyl alcohol (potato fusel oil), the least amount of which impairs the delicacy of the odor. In this country (the United States) there is no difficulty whatever in obtaining alcohol of proper strength. The market offers scarcely any other but that of 94%. Of course deodorized alcohol, or so-called Cologne spirit should be used. Grain and wine spirits are the kinds which when rectified are to be preferred to all others. All the citron oils (_i.e._, oils of lemon, bergamot, and those with similar odor), rose oils (oils of rose, geranium, and rhodium), and many other sweet scents are most fragrant when dissolved in pure spirit of wine, while the odors from the animal kingdom and those of violet (violet and orris root) smell sweetest when dissolved in grain spirit. The essences prepared from pomades or huiles antiques usually contain in solution some fat which is best removed by cooling. To this end the vessels containing the essences are placed in a vat and surrounded with pellets of ice and crystals of chloride of calcium. By this mixture the temperature can be reduced below-20° C. (-4° F.), and after some time the fats are deposited in a solid form at the bottom of the vessel. This is then taken from the vat and the essence carefully poured from the sediment. The alcoholic extracts of the pomades or solutions of the aromatics are called essences or extracts (French, extraits); the solutions obtained from resins and balsams are usually termed tinctures. While some extracts, owing to their strong odor, can be used only when diluted with alcohol, others are employed in perfumes as such. Pure extracts (extraits purs) are those containing only a single odor and are but rarely used as perfumes; the latter are usually mixtures of several, often a great many odors. CHAPTER XI. DIRECTIONS FOR MAKING THE MOST IMPORTANT ESSENCES AND EXTRACTS.