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Besides inulin, C12H20O10, a body isomeric with starch, the root contains helenin, C6H8O, a stearoptene, which may be prepared in white acicular crystals, insoluble in water, but freely soluble in alcohol.

Officinally Thymol, the stearoptene obtained from the volatile oil of Thymus vulgaris, is directed to be given in a dose of from half to two grains.

When hard spring water is employed, the otto is rich in stearoptene, but less transparent and fragrant.

Almost the only material used for artificially heightening the apparent proportion of stearoptene is said to be spermaceti, which is easily recognizable from its liability to settle down in a solid cake, and from its melting at 122° Fahr., whereas stearoptene fuses at 91.4° Fahr.

The odoriferous constitutent of the otto is a liquid containing oxygen, the solid hydrocarbon or stearoptene, with which it is combined, being absolutely devoid of perfume.