Alkylated azulenes free from alkyl groups in the 2-position and having a blue or substantially pure blue colour as shown by the absorption spectrum are prepared by the dehydration of a volatile oil such as callitris oil heavy camphor oil or guiacwood oil, gurjun balsam or a herb extract such as extract of chamomile or patchouli leaf.  According to the example, S-quaiazulene (1,4-dimethyl-7-isopropyl azulene) is prepared by heating guiacwood oil containing 65 per cent guaiol with sulphur at 150 DEG  to 300 DEG C. and preferably 180 DEG  to 250 DEG  C. until hydrogen sulphide escapes.  The product is extracted with phosphoric acid and petroleum ether, decomposed with water and purified by steam distillation, distillation in vacuo and by chromatography.  The azulenes as such, or in the form of addition products with maleic anhydride, picric acid or styphnic acid, or as halogenated or rhodonated derivatives are incorporated in cosmetic and therapeutic compositions (see Group VI).  Iodinated azulenes are obtained by treating with iodine or its compounds in chloroform or glacial acetic acid.ALSO:A cosmetic or therapeutic preparation comprises a base material and an alkylated azulene, other than chamazulene and free from alkyl groups in the 2-position, and having a blue or pure blue colour as shown by the absorption spectrum, or an addition product or derivative thereof. Specified azulenes are the natural and synthetic S-guaiazulene (1, 4-dimethyl-7-isopropyl azulene), 1-isopropyl-5,6-dimethyl azulene, 1-methyl-6 isopropyl azulene, the azulene obtained by dehydration of callitris oil, guiacwood oil and gurjum balsam and the azulene from heavy camphor oil, (see Group IV(b). 0.1 to 15 per cent, and preferably 0.5 to 10 per cent, of the azulene may be added to preparations containing volatile oils in order to reduce or eliminate the irritant action of the volatile oil.  Alternatively, preparations containing chamomile oil may be standardized with regard to their anti-irritant effect by the addition of an azulene of the invention. The azulene may be halogenated, rhodanated, combined with maleic anhydride, hydrated, or in the form of picrate or styphnate. Examples relate to (a) chamomile oil having enhanced content of azulene, (b) hair oil consisting of S-guaiazulene, paraffin oil, isopropyl palmitate and a fatty oil, (c) cold cream containing wool wax, paraffin oil, soft paraffin, lanolin, cholestrol, S-guaiazulene and water, (d) mouth rinse concentrate containing oils of peppermint, curlymint, geranium, clove and aniseed, menthol and tincture of myrrh and (e) artificial lilac oil containing phenyl ethyl alcohol, terpineol, amyl cinnamaldehyde, benzyl acetate, hydrocitronellol, heliotropin, nerolic oil, jasmine-flower oil, cinnamon alcohol, phenylacetaldehyde dimethyl acetal, fornesol, methyl-eugenol, ylang-ylang oil, civet tincture, dimethyl benzyl-carbinol anisaldehyde and S-guaiazulene.  The azulenes may be incorporated in dentrifices.  Therapeutic preparations comprise solutions of the azulenes in fats and oils, e.g. olive oil; volatile oils such as oil of helianthus, peppermint oil and thyme oil; hydrocarbons waxes, balsams and other solvents including alcohol with or without the further addition of medicaments such as menthol, ephedrine and disinfectants.