Page:Popular Science Monthly Volume 52.djvu/102

90 cases, the perfume continues to be given out, and is absorbed by the grease. Contemplating the matter from this point of view, we are astonished at the sagacity of the perfume extractors of past ages, which enabled them to perceive that some flowers could be treated only by this absorption process, and to co-ordinate their operations so logically that the method could not have been better adapted to its purpose if it had been adjusted after a careful study of the physiological principles involved. Everything in the process seems adapted to the prolongation of the life of the flower. The close and consequently moist atmosphere in which it is placed preserves it against dying; the coolness of the apparatus prevents its wilting. The flowers of the tuberose are picked just as the bud is about to open. It blooms within the case, and gives out nearly all its perfume there.

We draw from these observations the two lessons that the extraction of natural perfumes is not, as is often believed, a question of pure chemistry, but is primarily one of vegetable physiology; and that in this domain, as in many others, practice is often in advance of theory. For my own part, I have never met with well-established processes sanctioned by long use which do not rest upon correct though frequently unconscious observations over which theory has nothing to boast.

As when people wanted to travel faster they devised the railroad instead of improving the stagecoach, so the achievements of chemistry in the domain of perfumes have not been made in building up the old industry, but through creating another. To enumerate and describe the artificial products now used in perfumery would be like composing a manual of chemistry. It will be of more interest to indicate a few categories of syntheses or chemical fabrications, and to point out the various chemical or financial questions they raise, illustrating them severally by typical examples described in detail.

There are several kinds of synthesis. One kind consists in isolating a natural principle, studying it, and trying to reproduce it. Such a synthesis may be called a methodical one, as following out a line traced from the beginning. Take, for example, the synthesis of ionone, or artificial violet. The authors of this synthesis, MM. Tiemann and Krüger, started with the natural perfume of iris root, which they found to be very characteristic and fixed. It was consequently considered to be a single very definite and stable substance. All these conditions were favorable. The preliminary researches of the authors showed that this substance existed in extremely weak proportions in iris powder. The proposed synthesis, therefore, promised to be lucrative; for, while all chemical syntheses are interesting, the probable financial bearing of the discovery is of