The power which these bodies have of “fixing” a volatile substance, renders them valuable to the perfumer, independent of their aroma, which is due in many cases to benzoic acid, slightly modified by an esential oil peculiar to each substance, and which is taken up by the alcohol, together with a portion of resin.  When the perfume is put upon a handkerchief, the most volatile bodies disappear first:  thus, after the alcohol has evaporated, the odor of the ottos appear stronger; if it contains any resinous body, the ottos are held in solution, as it were, by the resin, and thus retained on the fabric.  Supposing a perfume to be made of otto only, without any “fixing” substance, then, as the perfume “dies away,” the olfactory nerve, if tutored, will detect its composition, for it spontaneously analyzes itself, no two ottos having the same volatility:  thus, make a mixture of rose, jasmine, and patchouly; the jasmine predominates first, then the rose, and, lastly, the patchouly, which will be found hours after the others have disappeared.

SYRINGA.—­The flowers of the Philadelphus coronarius, or common garden syringa, have an intense odor resembling the orange-blossom; so much so, that in America the plant is often termed “mock orange.”  A great deal of the pomatum sold as pommade surfin, a la fleur d’orange, by the manufacturers of Cannes, is nothing more than fine suet perfumed with syringa blossoms by the maceration process.  Fine syringa pomade could be made in England at a quarter the cost of what is paid for the so-called orange pomatum.

THYME.—­All the different species of thyme, but more particularly the lemon thyme, the Thymus serpyllum, as well as the marjorams, origanum, &c., yield by distillation fragrant ottos, that are extensively used by manufacturing perfumers for scenting soaps; though well adapted for this purpose, they do not answer at all in any other combinations.  Both in grease and in spirit all these ottos impart an herby smell (very naturally) rather than a flowery one, and, as a consequence, they are not considered recherche.

When any of these herbs are dried and ground, they usefully enter into the composition of sachet powders.

TONQUIN, or TONKA.—­The seeds of the Dipterix odorata are the tonquin or coumarouma beans of commerce.  When fresh they are exceedingly fragrant, having an intense odor of newly made hay.  The Anthoxanthum odoratum, or sweet-smelling vernal grass, to which new hay owes its odor, probably yields identically the same fragrant principle, and it is remarkable that both tonquin beans and vernal grass, while actually growing, are nearly scentless, but become rapidly aromatic when severed from the parent stock.