•,st advantage in the cyclic ethylene- :ol acetal of hydratropic aldehyde in the cruder and heavier note the di-methyl acetal. Upon careful selection, however, it•.i.•is found that there are quite a of the medial aliphatic which may be used in con- .•. •junction with the hydratropic and :i)'•?heptaldehydic acetals, particularly !•j•ithe secondary hexyl and nonyl ?i:i'i:"a'Cetates while, for example, definite :!i?'i'shadings can be borrowed from the i ii-i 0ur-earthy note of hexyl propionate, ?the'sweet mushroom-honey tone of •'i}i/6Ctyl propionate, the secondary- :i •.:!'fermentation fragrance of phenyl- i:i!ethyl caprylate,' the more floral, 'i:-iUngal-gardenia undertone of n- •.•:il n0nyl and n-decyl acetates and the 'i)11iPeculiar fungal-rose-orange complex ::•' of nonyl caprylate. ß •:•':'::•.:: The usage of such sweet, sickly :::i: bases is, as already indicated, that of an embellishment of the mossy ::and folial undertones, so that for i: :•. )ractical purposes in perfumery, :. i:fungal and earthy tones can be :.i•'regarded almost as synonyms. THE ROOTY COMPLEX : i The rhizomic odour would appear to be a composite note based upon :various proportions of the damp aroma associated with ferns, earth and fungus, with the peculiar dry and somewhat astringent tones of friable or crumbly earth, which in itself has a ligneous or powdered- bark back note. In this group the synthetic adju- rants play a comparatively minor PERFUMES role, as the odour of wild parsnip- seed oil epitomises the fernyoearthy- fungal tone, and this gives better results than items selected from the comparatively narrow gamut of octyl and octyl-crotonyl acetates, buryrates, propionates and laurates. From such a starting point, how- ever, via the oakmoss "esters," the note begins to embrace the lichenol inflection of p-iso-propyl quinoline and the labdanol shading of iso- butyl cinnamate, but from here the balance of the tonal elements must be sought among the natural pro- ducts. Probably the most descriptive adjective which can be applied to the rooty group is "dank," and, if the term can be accepted, then "essence of dankness" is well exem- plified by a blending of galbanum resinoid and immortel (everlasting) absolute, for in the latter is observed something of the liquorice note which contributes largely to fungal sweetness: a similar' sweetening action is also noticed in the inclusion of the perfumed bdellium, sweet myrrh or bissabol opoponax. From another angie of approach, Herabol myrrh, sassafras and asafce- tida exhibit a dry, powdery ligneous astringency, thus beginning to verge towards the woody note, but also from this departure point is seen the advent of aromatic and spicy warmth. via the ginger root, the methyl eugenol background of Canadian snake-root oil, leading to sumbul (musk-root), the musk lactones of angelica root and thence to the violet undertone of costus root and 193

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS iris rhizomes' and finally from the woody-rooty-cachou notes of cala- mus and patchouli to the familiar rooty-sandal fragrance of vetivert oil, its alcohols and esters all of which, when supported by clove stem, cinnamon leaf a.nd origanum oils, lead to a variety of pleasant aromas veering towards thee woody note. THE WOODY ODOURS The odours of the "precious woods," particularly cedar and san- dal, are very important in modern non-floral perfumery compositions and in this category, in view of the popularity of the citrus-incense-rose and "soir" perfumes, the vetiver note may be included. Although it is perhaps the deep, sweet and peculiarly fragrant and persistent santal-type odour associ- ated with vetiveryl acetate which has brought this ester to the fore- ground in recent years, yet it is important to realise not only the age-old Indian usage of khus-khus roots, but also the fact, noted by Piesse in his 1851 "Art of Perfum- ery," that in the early days of per- fumery in England, extracts incor- porating tinctures of vetivert roots, created quite a furore. It would appear, however, that of the aliphatic esters, vetiveryl acetate is outstanding in representing the quintessence of the vetiver characteristic without the dull and sombre notes of the oil. The other esters, from the formate to the valerianate, incline to an over- 194 fruity emphasis and, moreover, show a tendency to liberate the free acids, while the only other ester of interest is the pheny]acetate, which reveals, above the fundamental note of the acetate, as may perhaps be expected, a remarkable sweet, fruity-honey fragrance. Sandalwood 0il, E.I., like all the woody oils, is of considerable impor- tance in perfumery, not only because 'of its blending and mellowing action, but also for its equally outstanding fixative properties, which are seen to a marked extent in compounds for creams, brilliantines, bath salts, talcum and face powders. Although a deliberate overdose of sandalwood oil in a compound will result in an eastern or oriental type of aroma, yet in a.lcoholic perfumes the characteristic inflection of this oil is frequently obtrusive and more 2•.' pleasing results are achieved with':" Santalo]. Here also, the acetate is the out2 standing ester and is more stable and :it less fruity than the other aliphatics, I:! but the crystalline phenylacetate, i::: like the corresponding vetiveryl::: :? ester, is almost indispensable i n?•: powder perfumes and sachets. Support from any of the synthetics•'i is somewhat limited, but decahydroLi!: [•-naphthol formate, 'assisted benzophen0ne and phenylbutyl binol, provides a starting point industrial deodorants and somi• grades of soap perfumes, particulad•11 'i:i in' conjunction with Amyris Sandalwood, W.A.). Cedarwood 0il (Juniperus and Atlas Cedar (Cedrus ...?