THE ART OF THE PERFUMER 249 to cover much of the discoloration caused by the perfume, and if all known aromatics which cause discoloration were to be eliminated the perfumer would have a very limited number to work with. This would result in only a very small number of perfume complexes. Care must also be exercised to produce a product of quality, and the soap base should be carefully controlled to prevent the development of rancidity and to ensure that the odour of the base is as silent and as fresh as possible. The odour of so many soap bases influence the result of the perfume, and if on}y a base is used that is in itself fresh and clean a much better result will be obtained at a lower cost, as the amount of perfume can be reduced when there is little basic odour to cover. There is a tendency to use cheaper compounds in soap than are used in other toiletries, and although soap will absorb the odour of some of the impurities in the aromatics it must not be assumed that this is good practice. If the preparation is carefully made and there is little basic odour to cover, the use of a good quality perfume can be advantageous and the result will be more fragrant and pleasing, but there can also be a reduction in perfume content. Nail varnish perfumes present their own problems, too. Whilst it is not possible to cover the basic odour of the varnish it is possible to adopt a perfume which remains after the varnish has dried. This perfume must not have any deleterious effect on the varnish, such as interfering with the drying properties or affecting the colour in any way. Although this is obviously known to the cosmetic chemist, the perfumer should be a/so aware of these problems, and not include products which are known to affect the properties of a nail varnish. This is a further instance in which the perfumer and chemist must co-operate to get the best effects. With all this in mind it is quite impossible to have an identical perfume in a range of products, and some compromise must be adopted. In arriving at a compromise the perfumer is often requested to prepare perfumes to a price limit and is therefore forced to downgrade the quality of a compound. The selling price of most cosmetic preparations will permit the use of a good perfume, that is, a perfume of good quality and taste. Only very few per- fumes can be produced at a reasonably low cost. There are no standards, but one can be guided in floral complexes by their proximity to the natural perfumes of flowers. These natural perfumes possess a very high standard of quality, and it is this standard that the perfumer is always striving to achieve as in all instances of artistic development, an aesthetic taste is necessary. We are all aware that it is not possible to satisfy all tastes and that odour appreciations vary considerably, but the experienced user can easily judge a good perfume. The fact that a perfume does play an important part in the evaluation of a cosmetic product must not be overlooked. Often we see preparations that have a complex completely unsuited to the product, being either of a wrong type of perfume or of cheap quality. Not all corn-

250 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS plexes can be adopted for a particular line if it is to be correctly perfumed, and it is much better for a perfumer to design a perfume than to endearour to modify an existing one just to retain a similar tonality throughout a range of products. The reason for the co-operation between the cosmetic chemist and the perfumer is evident when a cosmetic preparation shows deterioration. The formulation must be examined to determine whether the perfume used is the cause or whether the preparation would break down irrespective of the added perfume. In such cases (and we do come across them), the whole formulation of the cosmetic preparation must be adjusted to accept a perfume, and the perfume must be adjusted where it is proven that a particu- lar component is the aggressor. It may be that the perfume is being added at the wrong stage of manufacture, and this should be taken care of. This is a little more important than is at first envisaged, and the perfume in a preparation might well appear much better if it had been added at the correct stage in the manufacture this again is where the chemist and perfumer should work together to obtain the best results. It may also be possible that a reduction in perfume content could be effected by this means and thus effect a saving in manufacturing costs. We often have complaints of discoloration, a phenomenon which shows mostly after an ageing period. This can be due to many causes, and a close examination of the components of the cosmetic pack might possibly reveal the cause. Insolubility of perfume in a liquid preparation is another trouble- some problem which must be overcome, and it is only when knowing the formulation that the perfumer can take the necessary precautions to eliminate the insoluble matehals in this compound. Whilst the cosmetic chemist might not be aware of solubilities of perfumery matehals, the perfumer would know the solubility of the ingredients of his creation. The advent of aerosol products has brought tremendous perfumery problems. The many factors that have to be controlled to ensure that the perfume does not deteriorate include the solubility of the perfume in an aerosol formulation, the stability, and the possibility of aromatic bodies being irritants. This method of dispensing a perfume and the results obtained are so completely different from all previous methods and results that the perfumer has had to revise the techniques employed in creating a perfume for use in this medium. The whole of the complex--the top notes, the heart, and the residual notes--are instantaneously atomised into the atmosphere, and the result is completely different from that obtained when using the conventional air spray. This difference is great, and to obtain similar results by the two spray methods two different perfumes would have to be prepared. Because there are so many factors governing the creation of a perfume for aerosol dispensing prior to being finalised it must be subiected to a shelf-test in a loaded aerosol for a period of not less than six months to