14 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS almost everything that is used in the factory. We have not studied it quantitatively, but it is actually a nuisance in this kind of work. MR. L. Gr.ArJsirJsz: Could you describe in some detail how you decide upon the proportions, especially in the head space ? THE L•CTrJRER: The vessel that was used in some of this work consists of a jar covered by a glass plate with a piece of wire going through it. To analyse the yapours of a rose you need a vessel large enough to contain the flower without crushing, but it still should not be bigger than necessary. In the experiments described, the rose was put into a beaker and the platinum wire with the drop of dibutyl phthalate was suspended from the cover. The whole was then put into a desiccator which was evacuated to about 20 mm. The vacuum is important because the diffusion rate is inversely proportional to the pressure. DR. J. D. BAC•HrJRST: If a drop of, say, dibutyl phthalate is suspended above a rose in a closed system, is the distribution of components in the dibutyl phthalate when equilibrium is reached the same as that obtained by solvent extraction of the rose by dibutyl phthalate? Tr•E L•-CTrJR•.R: Are you wondering why dibutyl phthalate was chosen? DR. J. D. BXCKHrJRS•: No, if you use any solvent--I chose dibutyl phthalate because you had used it with your rose--would you get the same chromatogram if you had actually extracted the rose with dibutyl phthalate? THE LEC•rJR•-R: That may be so if the extraction is only partial, but you must remember that the equilibrium is produced specifically for dibutyl phthalate. If I had used another high boiling solvent, say a hydrocarbon, then I would not necessarily get the same chromatogram because the concentration of absorbed volatile material required to produce a given vapour pressure depends upon the polarity of the solvent. One thing is certain--if I had used a hydrocarbon instead of dibutyl phthalate then I would still get a composition in the hydrocarbon which would reproduce the odour of the rose. The liquid composition would be different because you are using a non-polar absorbing solvent, but the vapour composition would be the same. You know, for example, that water in a perfume suppresses the partial vapour pressure of phenylethyl alcohol. The same composition containing phenylethyl alcohol made up in, say, medicinal paraffin or something similar, instead of aqueous spirit, would have a much higher partial pressure of phenylethyl alcohol and it would smell different. Probably dibutyl phthalate is just about equivalent to alcohol, so that it would be better in that respect. MR. J. H•CKFOR•H-JoN•s: Perfumers are familiar with the differences between the odours of products smelled statically--as when wrapped--or smelled dynamically, their perfumes wafted around by convection currents. Do you intend to examine the effect of convection on the experiment? THE LECTURER: That point has not been considered in the present work, but it may be connected with the composition of the drop at some intermediate time before equilibrium has been established.

J. Soc. Cosmet. Chem. 22 ! 5-26 (1071) ¸ 1971 Society of Cosmetic Chemists of Great Britain Odor and optical activity E. T. THEIMER and MINA R. McDANIEL* Presented in part at the Symposium on "Perfumery", organised by the British Society of Perfumers and the Society of Cosmetic Chemists of Great Britain, at Eastbourne, Sussex, on 21st April 1970. Synopsis--The important question whether optical ANTIPODES of odorous compounds can be discriminated by the human OLFACTORY system, has as yet not been answered un- equivocally. Previous studies on the ODOR perception of d and l isomers provided no mechan- ism for eliminating the effect of trace impurities. In the present study, five compounds with fragrance odors were each prepared in four forms dextro a, dextro •, laevo a, laevo [•. Because of the synthetic routes used, the two a materials contained similar trace impurities, as did the two • materials. Ability to discriminate was determined by panel testing using both "lay" and "expert" subjects. The results showed that dextro and laavo forms could be distinguished in every case. The TECHNIQUES employed surmount the problem of the presence of unavoidablo trace IMPURITIES and produce results leading to con- clusions having statistica'ly high confidence factors. The importance of using panels was made clear by cases of individuals lacking discrimin- atory ability. Since this ability depended upon the compound being examined, as well as upon the individual, anosmias are postulated which may be limited to chirality and are thus called specific CHIRAL ANOSMIA. INTRODUCTION Molecular structure determines the quality and intensity of olfactory stimuli evoked by chemical compounds. However, the relationship between structure and odor, which has been studied for many classes of compounds, remains strictly empirical, although the importance of even minor structural differences in determining olfactory characteristics is well established. Thus geometrical isomers, whether ortho/meta/para, cis/trans, exo/endo, etc., are in most cases readily distinguished both as to quality and strength. On the other hand, the influence of optical rotation on odor remains *International Flavors & Fragrances, Union Beach, N.J. 07735, U.S.A. 15