8 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS form crystalline magmas with certain alcohols, while Tiemann, in 1898, oxidised geraniol to citral and subsequently reduced this aldehyde and regenerated the alcohol. 0DOUR-PATTERNS It is here instructive to recall Pie. sse's remark regardi•ng this rose-leaf geranium, for h e says ß "... the leaves of this plant yield by distillation a very agreeable rose-smelling otto, so much resembling the real Otto of Rose, that it is used very extensively for the adulteration of that valuable scent .... ' ' I have used elsewhere the term "fragrance-pattern" and illustrated it by a diad or triad of well-defined floral types selected from the groups of fragrances arranged in tabular for m a•cording to my interpretation of their order of relative importance i•n perfumery compounding. This has been based upon a systematic analysis of several hundreds of the more charac- teristic type-formulae as presented in the various perfumery recipe books from 1855 onwards, and almost automatically verified by the cumulative indices in my laboratory notebooks. From this statistical data definite evidence emerges of what has often, but somewhat casually, been mentioned in the litei'ature, namely, that there is scarcely a perfume base in which the elements of rose, j asmin or neroli do not appear in some form or other. In my Tabulation of Blossom Fragrances, initial consideration is afforded to two groups each containing f/re basic odours, proportional admixture of which results in the evolution, first of the simple exotics and then the more complex floral odours, but whatever the angle of approach may be, it will invariably be found that attention gravitates towards the rose content. I therefore feel that in so far as the essentials of perfumery compounding are concerned, the prime odours should be regarded as having odour-patterns, reserving the termfragrance-patterns to define with some precision the osmical end-points of prime odour combination. This approach opens a very interesting vista, because, for example, in the case of the rose, not only does the noun name and place the flower, but analysis of the essential oil derived from it reveals the type and quantity present of the dominant and recessive osmophores, from which, usually with a large measure of success, reconstitution of the otto of rose aroma is possible. THE GERANIUM FRAGRANCE Consideration of the geranium oils affords another opportunity of dealing with an important item in the commerce of perfumery raw materials and at the same time to appreciate the value of the data now available in the litera- ture of the essential oils concerning their chemical and physical properties,

THE GERANIUM FAMILY IN PERFUMERY 9 which is of considerable help to the perfumer, for not only has he at his disposal from the various supply houses the segregated components of an essential oil in a high degree of purity but he can profit in several other directions. Among these, for examl•le , is the encouraging th'ought that he is not entirely dependent upon ihe gera, uium oils for his gemniol, as there are far more economical sources in the citronella and Palmarosa •)ils, which by processing yield isolates and esters closely approximating thos• found in geranium oil but others, although alien, possess the family nuance and facilitate the production of compounded oils of outstanding strength •[nd tenacity--an accomplishment, incidentally, which is aided by the incorpora- tion of such purely synthetic aromatic's not found in nature as benz0- and rose-phenones and diphenyl-oxide and -methane, which possess •harac- teristic rose-like and geranium-leaf odours. I think that geranium oil may be regarded as one of Nature's 'master- pieces, and one which, early in the experience of the student-perfumer, will amply repay the effort of a prolonged study. 'BouRBON AND OTHER GERANIUM 0ILS Reference to the literature will indicate somewhat prosaically (in round figures) that the total alcohols in Bourbon geranium, regarded as geraniol, will vary between 65 and 70 per •enl the, ester content, calculated as geranyl riglate, about 25 to 30 per cent, while the apparent citronellol is approximately 40 to 50 per cent. This is laconic and not particularly 'interesting, but a closer approach reveals what may •)erhaps be aptly termed an osmical panorama, for in the foreground, and supporting the geraniol and citronellol, we find the presence of small quantities of terpineol, linalol, bornyl, amyl and hexyl alcohols. In the background are the particularly reactive acids--acetic, burytic, caproic, tiglic and valeric which in liaison with the alcohols are capable of theoretically engendering Upwards,of thirty esters. Of course, such a com- prehensive inter-esterification does not take place in the plant nevertheless, it is as well to bear in mind that some of the more probable formulations, for example, the acetates and valerates of amyl alcohol, b9rneol and terpineol, are so powerful that their natural (or intentional) incidence must be in such small traces just evident enough to be regarded as modifying agents. To add to the complexity of constitution, yet obviously playing an impor- tant part in the composure of the fragrance, are the trace elements--citral, menthone, pulegone, pinene, phellandrene and their isomers. Geranium Bourbon is also remarkable for the relatively small amount of terpenes it contains, and, in my opinion, the potential of the full depth and beautiful fragrance of this oil is seen in two d.irections, firstly in the terpene-