A CLASSIFICATION OF ODOURS AND ITS USES W. A. POUCHER, F.P.S., F.R.P.S. The Author develops a classification of offours based upon rate o• volatil- isation, and shows the l•raetical usefuless of this system. P•RFUMER¾ HAS often been compared with music and xvith painting', in that creative work in all of them requires the artistic application of similar basic principles ß if the fragrance, symphony or canvas is to receive general approbation, or even dire comment, from both critic and public. There is a parallel in the original motif of each ß for the musician builds up a series of notes to form his new theme the painter discovers a beautiful scene and makes a rough sketch of his new subject and the perturner subtly blends certain tenacious aromatics to produce his new base. The elaboration of each idea demands a wide knowledge from the originator, a persistence of purpose and immense patience if the motif is ultimately to attain perfection. The cronposer must understand both harmony and counterpoint, together with the special qualities of each instrument in the orchestra. He may use one or more of them to modulate his theme, and the others to impart a harmonious background' the whole producing an intricate tone poem in which he may vary his rhythm and key to retain and charm the ear of the listener. The painter must be a master of colour blending, and especially so of the greys, if he is not only effectively to portray his subject, but also to impartfl atmosphere, lighting and perspective to his finished canvas. The perfumer must have an intimate knowledge of perhaps a thousand.li?: aromatic substances, he must be familiar with the odour value of each its !i source and the characters that determine its quality, as •vell as its type and blending range. Moreover, he must also select and use each one them skilfully to compose, reinforce and shade his basic note until it a symphony of fragrance. But this is not all for if his creation is to employed as a perfume for cosmetics and soaps he must also have a knowledge of their composition and the effect each of their raw will have upon every constituent of his original fragrance, which cunning substitution and fresh blending ultimately to achieve the finished note. Of the three arts, it might be said that the appraisal of painting easiest. because the permanence of each canvas allows it to be more standably appreciated and assessed by the eye, xvhereas the intangible of both music and perfumery defeats any concrete evaluation b' or nose. Now, it is strange but true that the fundamentals of the three arts equally understood for on both music and painting many detailed 8O

A CLASSIFICATION OF ODOURS AND ITS USES hax'e been published that can be studied by the potential composer or painter, and from which much guidance may be obtained in the course of their work. It is also true that research has provided a solid background to the work of the perfumer, in so far as the chemical and physical constants of each of his raw m•terials have been established, as well as the almost complete analysis o[ most of the essential oils, flower concretes and absolutes, all of which are available in many text-books. Yet, despite this fund of information, it is unfortunate that none of it is of any real value in his creative work. I, myself, may have been guilty of offering, in my three works, suggestions and perhaps even novel ideas that the imaginative experimenter may employ and elaborate in the practice of his profession, but I freely admit that they are more useful to the novice than as a guide and friend to the expert. When I •vrote my first book on perfumery I was conscious of this defect, and although more information is available to-day on what I will call the "Missing Link," and it is still being investigated by different chemists both here and in Europe, nothing of a practical nature had then been published about it. This link is a Classification of Odours and its application, and it was as long ago as 192½ that I began serious work upon it in an attempt to evolve a grouping of aromatic substances on a really sound basis. It took me no less than four years to complete, and you may well speculate upon the reasons why I did not publish the results in the next edition of my books. But at the time I felt it was too valuable for widespread diffusion, and it gives me pleasure to tell you about it here and now since the eve of my departure from the industry is approaching. Before the introduction of synthetics the problem of classification was not quite such a difficult one, because the perfumer had at his command only the commoner essential oils and flower extracts. Chemistry has since evolved not only numerous shades of each odour type, but it has also created entirely new perfume bases. Moreover, many more essential oils are now available, and the whole gamut consists of perhaps a thousand ra•v materials against a former fifth of that number. Rimmel was the first to endeavour to classify the then known substances, and he did so by adopting a type for each class of odours and grouping with them other materials of similar fragrance. He was able to reduce his classification to eighteen distinct types. Piesse later took quite a different view of this problem, and compared odours with sounds. He suggested octaves of odours like octaves in music, where certain odours coincided like the keys of a piano. For instance, one octave might consist of the citrus oils another of almond, heliotrope and vanilla and still another of patchouli, santal and vetivert. These sub- stances certainly blend most admirably: •vith the first as the top note, the second as the middle note, and the third as the base. He eventually arranged the primary odours in positions corresponding with their perception 81