perfumed as on a cool September morning, although I should never be inclined to call any morning “incense-breathing,” like Gray, for anything less like incense could scarcely be imagined.
There is no doubt, however, that frost seals up all odorivectors and renders the air quite odourless.
A physical law appertaining to gases is also invoked to explain the “clinging” of odours. Many, if not all, solids and liquids when exposed to air and other gases adsorb (cause to adhere) to their surfaces a thin, dense layer or film of the gas. If now that gas happens to contain an odour, or is itself odorous, the odour must also be adsorbed, and so in the case of porous materials, such as fabrics, permeated by the odour, it lingers tenaciously in their depths.
Odorous bodies in the solid or powdered form are known to retain their perfume for prolonged periods, Look how long a sandal-wood box remains aromatic. This property is supposed to depend upon the lowered vapour tension of the odorous molecules in the depths of the solid or powder, in virtue of which they rise into the air, or evaporate, but slowly.
It would seem to bc natural to suppose that, as vaporisation plays such an important part in the dissemination of odours, the volatile bodies and liquids would be more odorous than the non--
