Abstract. From a data bank of 2467 odoriferous products, the similarities between 74 notes used in perfumery were calculated. The similarity matrix (74,74) contains -63% of zero values and shows that only a few pairs of notes present high similarity coefficients. A fine analysis using ascending hierarchical taxonomy with the complete linkage procedure shows that 14 notes are isolated while 60 notes are regrouped in 27 groups containing two to four notes. The isolated notes correspond to well-defined structural particularities. Some pairs of notes or groups present similarities in their chemical structures but some groups are built on the basis of semantic processes. This study shows that the notes are generally independent, with no strict hierarchy among them, and rules out the existence of primary odors.

Preconceptions of first-year university students of the constituents of matter and the notions of acids and bases were investigated on a total of 400 students. The procedure used consisted of free interviews, semi-structured interviews and questionnaires.It was found that the constituents of matter were well known to students, but that interactions between these constituents were either totally unknown or were the subject of severe misconceptions. The students' knowledge tended to be qualitative and formal, with a worrying lack of connection with everyday life.

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Abstract. In order to analyze the relationships among 32 descriptors of odors (notes), similarity coefficients were calculated using a data bank of 628 odoriferous products. The simple examination of the similarity matrix (32,32) has shown notes selectively and strongly associated (e.g. camphoraceous -pincy and musky-powdery) and others less selectively associated (e.g. floral, green and herbaceous). This analysis was completed by four multivariate statistical methods. Non-linear mapping (NLM) proved to be more efficient than principal coordinates analysis for planar representation of olfactory notes, and has given results similar to those previously obtained using other data and other methods (similar disposition of notes around the central note 'floral'). Furthermore, the ascending hierarchical taxonomy and the minimal spanning tree were coherent with the NLM representation. These three methods complete each other and constitute a convenient system to analyze odor descriptions.

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Two models, derived from the equations of Michaelis-Menten and Hill, were adapted to olfaction. Their ability to model human olfactory stimulus-response relationships was compared with that of the classical laws of Fechner and Stevens. First, these four models were systematically compared on data available in the literature concerning 20 pure odorous compounds. At the lower concentrations of the odorous compound, the model of Stevens was found to be as good as the model of Hill. However, when the concentration range was extended further and included the concentration at half the maximum intensity, the model of Hill was found to be better. Second, the four models were tested on different parts of a true stimulus-response sigmoid curve with 5% noise added. The comparison confirmed the results obtained when experimental data were used. Third, the hypothesis that the psychophysical response is the sum of sigmoidal responses generated at the more peripheral parts of the olfactory system was examined, assuming a binomial distribution of receptor affinities. Within a very large range of variation in their characteristics, the sums of several sigmoids are indeed correctly modelled by Hill equations with exponents reflecting the distribution of receptor affinities.

A number of structure-odor relationships concerning odor intensity and odor quality are presented. The sets which were used, the statistical methods which were employed and the principal results of the studies are analyzed and discussed. An attempt was made to recognize principal trends in the field of structure-odor relationships.

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