TALKING OF PERFUMES AGAIN Information in the form of molecules is fed to the nose where it is fixed via its relative solubility at the interface. Here it takes on a penetrative shape determined by the bonding angles. Electric charges are allowed to pass through the "punched card" and proceed to the olfactory receptors which relay the appropriate message to the brain. It is quite beyond me to enlarge on these vague and unhelpful ideas. DEFINITION I have elsewhere suggested that perfumery may be defined as the art of producing or creating a pleasant impression by blending some or many odours and that a simple mixing of odoriferous ingredients may not necessarily pro- duce a harmonious effect. Despite the efforts of certain modern "artists," perfection of subject-matter is the art of the painter and sculptor, and the value of his work may be iudged by all with eyes to see. Music and perfum- ery are less tangible to the senses and consequently less easy to define anG appreciate. With music, a "mixture" of notes may or may not produce' harmony to the ear the skill of the arranger and dispenser will determine' this point. Even in this case only the expert can critically judge the quality of a piece of music and the way in which it is presented. In much the same way we can arrange our odour notes and present them for the approval of the nose, and whilst the expert will obviously be capable of a more critical examination, the individual, as with music, "knows what he likes." It is almost as easy to strike the wrong note in perfumery as in music, although, thankfully, I say less people will be aware of the fact. TRAINING Are perfumers made or born ? I suppose each successful perfumer must "have it in him," but, as in all walks of life, long and arduous practice is the keynote to success. There are so many thousands of ingredients to consider and so many ways in which to use them. Perhaps consideration of the training of a perfumer would offer an introduction to his ultimate require- ments. Unfortunately, there are no organised schools of perfumery and no accepted curriculum. One can only indicate the methods one would person- ally adopt or recomlnend. Let us assume that the trainee starts with a reasonable knowledge of chemistry, particularly organic chemistry--that is the chemistry of the carbon compounds which comprise the raw materials with which he will work. For the moment he is not concerned with theories or physics, but with becoming familiar with his perfumery ingredients. What have we to offer our hopeful by way of vocabulary ? Precious little which will help him. Classifications have been made and whilst perfumers in general can understand each other to a certain extent, no two people appear to agree on all points. It will be necessary to show him a selected number of important ingredients those essential oils or synthetics in most common 185

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS use, and for him to memorise them so that he will immediately recognise them individually and in certain simple cases when occurring in combination with each other. We might well select bergamot, lemon, lavender, bols de rose, geranium, vetivert and sandalwood from amongst our essential oil group. Hydroxycitronellal, benzyl acetate, linalool, linalyl acetate, amyl cinnamic aidehyde, phenyl ethyl alcohol, alpha ionone, musk ketone, musk ambrette, geraniol, terpineol and methyl nonyl acetaldehyde might form a fair selection from our synthetic range. Add to this one high boiling solvent in case our solids exceed the limit of solubility in our mixture and to act as a general "fixative." Benzyl benzoate may be our choice. I hope to make mention of "fixation" later in this talk. An association of ideas is the finest basis for remembering or identifying an odour. In this connection, a knowledge of chemistry or a method of extraction or manufacture leaves an unforgettable impression on the memory and opens the way to other similar appreciations. The expression "aldehydic" may mean little to a non-technical person, even although he has often smelled such products, but to have a clear picture of an aidehyde, to visualise that reactive carbonyl group, its relationship to alcohols and acids, is to retain its odour in the memory, not only for each individual aidehyde, but as a general classification. Most experienced perfumers would successfully place a new chemical in the appropriate class--alcohol, aidehyde, ketone, ester, etc. Starting with the essential oils, which are volatile products of vegetable origin, our trainee is off to an easy start. The lemon sucked at half-time, the piece of lavender head idly plucked from a convenient garden, etc. Synthetics are more difficult to associate with events or known things and one may be forced to cheat a little and associate them with essential oils, fruits or flowers. Thus one can easily connect linalool and linalyl acetate with bergamot oil and lavender, phenyl ethyl alcohol with the full note of the rose and ionone with the violet. Very many more instances may be quoted, and, as the perruiner progresses, so his field of associations widens. For instance, he will in time connect amyl cinnamic aidehyde and benzyl acetate with the odour of jasmin, hydroxycitronellal with the odour of lily of the valley and lilac, but only after he has made those associations by practical experimentation. Undoubtedly the hardest but most efficacious way of remembering your raw materials is to handle them in an intimate manner, that is seek closer contact by working as an analyst in a fine chemical laboratory, an operative in a factory producing isolates or synthetics. You will never forget the iso eugenol which refused to solidify at temperatures far below its melting-point and then does so when you put it away in disgust. Remember those inter- minable melting-points and recordings of results ? Musk ambrette 85 ø C., musk ketone 136 ø C., musk xylol 113 ø C., except when it became stubborn and reverted to its other form and melted at 105 ø C. ? Remember the way 186