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-

10 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS less oil, and secondly the result from careful fractionating which yields the rhodinol of commerce. Without attempting any comment upon the unsettled question of the chemistry of the rhodinols, it may be noted in the pelargonium and in other flower oils that geraniol is associated with the laevorotatory form of citronellol. The proportional balance in the R6union oil may be regarded as 50: 50 whereas the oils of African origin average about 80: 20 those of French distillation showing approximately 70: 30 and the Spanish oils 60: 40, noting in passing that it is usually the French oil which is distilled over rose petals to yield the beautiful Geranium sur Rose. It would therefore appear that this equipoise in the Bourbon oil provides an ideal foundation for simulations of Bulgarian otto of rose, while increasing the content of/-citronellol emphasises the lighter and sweeter nuances of rose centifolia, Damascene, the moss and the tea roses. THE "GRASS" OILS It is also instructive briefly to review several of the economical sources from which the geranium oils of commerce are obtained and to note the variations in the odour-patterns of these oils which are distilled, not from leaves, but from flowering grasses. In order of importance these are Pal- marosa and the Java, Ceylon and Formosa citronella oils. Distillation in India of Cymbopogon Martini var. (Motia-.•ass) yields Palmarosa or "Turkish" geranium oil (containing from 75 to 90 per cent of free geraniol) which has a fine, soft, mellow rose-geranium odour singularly free from unwanted alien off-notes, which is not unduly surprising when it is noted that the addendum is brief, consisting chiefly of small quantities of the acetic and caproic geranyl esters, methyl heptenone and dipentene. Another example from a similar species known locally as Sofia-grass yields ginger-grass oil, but in this instance the geraniol in a much smaller yield is associated with an entirely different framework formulated around the presence of carvone, dihydrocuminol, phellandrene apd dipentene, from which emerges a strong and somewhat unpleasant herbal back-note which is difficult to eliminate from the geraniol even by repeated fractionation. Java citronella, distilled from C. nardus, is interesting for several reasons, firstly because it introduces us to a very important source of a fine quality geraniol, and secondly, whereas this alcohol is found in liaison with/-citronellol in Bourbon geranium, in the Java oil its companion is the aidehyde d- citrondial to the extent of about 35 per cent of each. This aidehyde, when reduced, provides the d-citronellol of commerce, but it must be observed on comparison that there is a considerable odour difference between the relatively coarse rose-type scent of the dextro-version and the refined, suave and sweeter rosy fragrance of the laevo-modification.