On Sense And The Sensible   

incline to refer odour to this cause [sc. exhalation of some sort],

but some regard it as aqueous, others as fumid, exhalation; while

others, again, hold it to be either. Aqueous exhalation is merely a

form of moisture, but fumid exhalation is, as already remarked,

composed of Air and Earth. The former when condensed turns into water;

the latter, in a particular species of earth. Now, it is unlikely that

odour is either of these. For vaporous exhalation consists of mere

water [which, being tasteless, is inodorous]; and fumid exhalation

cannot occur in water at all, though, as has been before stated,

aquatic creatures also have the sense of smell.

Again, the exhalation theory of odour is analogous to the theory

of emanations. If, therefore, the latter is untenable, so, too, is the

former.

It is clearly conceivable that the Moist, whether in air (for air,

too, is essentially moist) or in water, should imbibe the influence

of, and have effects wrought in it by, the Sapid Dryness. Moreover, if

the Dry produces in moist media, i.e. water and air, an effect as of

something washed out in them, it is manifest that odours must be

something analogous to savours. Nay, indeed, this analogy is, in

some instances, a fact [registered in language]; for odours as well as

savours are spoken of as pungent, sweet, harsh, astringent rich

[='savoury']; and one might regard fetid smells as analogous to bitter

tastes; which explains why the former are offensive to inhalation as

the latter are to deglutition. It is clear, therefore, that Odour is

in both water and air what Savour is in water alone. This explains why

coldness and freezing render Savours dull, and abolish odours

altogether; for cooling and freezing tend to annul the kinetic heat

which helps to fabricate sapidity.

There are two species of the Odorous. For the statement of certain

writers that the odorous is not divisible into species is false; it is

so divisible. We must here define the sense in which these species are

to be admitted or denied.