THE ART OF THE ?ERFUMER 245 more volatile than their resinoid counterparts, have more influence over the perfume during its earlier stage of evaporation and do not influence the residual note quite as much. There are many occasions in perfumery when this is desirable. Overdosing of a compound must be guarded agairmt, as the influence of these oils is very powerful. The use of these oils is growing and they are contained in many of the modem compositions. Their obvious presence in some compositions unfortunately detracts from the •esthetic value of the perfume. Mention must also be made of the few animal products used in perfumery and the tremendous influence they have over a perfume. Most perfumes are improved by a careful addition of one or more of the animal products. To even out the variation in odour value experienced with different consign- ments it is advisable to prepare solutions of these animal products. The best method is the addition of an alcoholic tincture to the finished perfume at the time of compounding. These tinctures should be at least six months old before use and the perfume with the added tinctures must be allowed to mature for a further six to twelve months' period. For a non-alchoholic product an extract in a solvent such as benzyl benzoate is advised and this can be added to the compound. The influences of these animal products are not felt until a suitable maturing time has elapsed, and this also applies when the substituted or synthetic animal products are used. These synthetically prepared bodies are not complete substitutes for the natural products but have frequently to be used for reasons of economy. Specialities should be used by the perfumer if they give him the assistance he needs for developing a complex. A speciality is a basic compound and is used to impart a special note to a perfume, whilst a compound is a finished product of such concentration that it can be used to perfume powders, creams, soaps, toilet waters, handkerchief perfumes, etc. Many specialities have been prepared by chemists after extensive research, and invariably they are stable products giving little odour variation from batch to batch. Several of the great perfumes of yesterday and to-day contain special/ties, and indeed the success of some can be attributed to these products, without which the perfumer would find it even more difficult to obtain a note of distinction. Some of these specialities are blends of several bodies and when they are included in a perfume they give the perfumer an opportunity of using some of the tremendous number of new aromatics of which he might not be aware or perhaps has forgotten. This is not intended to convey that each and every composition should contain a quota of specialities, nor do I consider that a perfumer should prepare a perfume just by mixing a few specialities, but it is advisable to examine the specialities very carefully and to choose wisely the correct type in order to produce the necessary warmth or tonality of depth or other note which the perfumer feels necessary for rounding off his creation. I do not hold the view that expert and experi-

246 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS enced perfumers should not use these specialities and that they should be skilful enough to prepare their own. I consider that however experienced and skilful a perfumer is he must accept and admire the work of other perfumers and chemists, and he should be ready to use the results of their skill and imagination, for without this readiness he cannot hope to obtain results any more than if he attempted to create perfumes xvithout the use of essential oils. The preparation of these products is a very specialised operation and always requires the services of highly skilled chemists and complex plant or apparatus. The specialities which are offered as substitutes of a natural product do not give a completely satisfying result. Their influence over a compound is different, there is a lacking in the warmth and tonality given by a natural product. Nevertheless, they are of great value when correctly used and there are many occasions when they can be intro- duced with advantage into new compounds instead of using the costly natural materials. Although only passing mention has been made of the isolates, derivatives and synthetics it must be obvious that there is no intention whatsoever on my part of underestimating their uses or belittling them. They are being produced to-day in ever-growing numbers so that at times the perfumer would welcome chemists taking much longer vacations. The number of these products is now prodigious and to attempt to memorise the odours of them is a tremendous task. Not even the most skilled perfumer could pretend to be familiar with them all. At the same time there must be some endeavour to test the new products in order to determine whether a new complex has been produced or whether they can benefit from any existing preparations. It is perhaps a little disappointing that from the countless numbers of these aromatic bodies there have been very few over the past years to give an entirely new complex or perfume base, and the perfumer who is constantly searching for new ideas would welcome any aromatic which would enable him to produce an entirely new complex, particularly one that would be accepted throughout the perfumery world. It would be fair at this juncture to say that there is a general improvement in the quality of the isolates and synthetics being produced to-day as compared with pre-war, whilst it is also true to say that the quality of the natural products has not improved. The very vehicle that is carrying the perfume has a tremendous influence on the final odour appreciation. A perfume coming off alcohol has quite a different impact on the olfactory senses than the same perfume coming off a cream or powder, and this without taking into consideration the chemical differences of the vehicles. All cosmetic raw materials have an odour which has an influence on the odour of the perfumed preparation, and I do recom- mend that great care is taken when choosing ingredients for a cosmetic preparation. When a formulation has been decided on the cosmetic chemist