The principal characteristics of the sense of Smell are common to that of Taste also. The two senses resemble each other in being both powerful as instruments of feeling, and proportionally weak as sources of information.
Tastes, like smells, admit of hardly any classification, except in respect of their relation to the sensitive organism, as pleasant or painful. Like smell, too, the sensation appears to be produced by means of sapid particles emitted from the body, and brought into contact with the nerves; and these particles, which constitute the object of the sense of taste, are in their own nature as little known as those of smell, and can as little be regarded as bearing any resemblance to the sensations which they excite.
Taste, like smell, is thus a modification of touch; the object in contact with the organ being the sapid particles, and not, as might at first be supposed, the body from which those particles proceed. The body is in contact, not with the nerves, but only with their exterior covering; and in order to produce the distinctive sensation of taste, it appears to be necessary that the sapid particles should be dissolved in the saliva, and thus penetrate through the investments of the papillae into their substance.
But, not to enter here on questions more properly belonging to physiology, it will be sufficient for our present purpose to observe that taste, like smell, conveys no knowledge of the existence of extra-organic matter, and that the sensation, properly so called, consists in the consciousness of the organism as affected in a particular manner, agreeable or disagreeable; while the perception is to be found in the corresponding consciousness of the locality of the affection in the organism as extended. these two are always to a certain extent co-existent, yet the former predominates so far over the latter as to form the principal characteristic of this class of sensations.
For this reason, the organs of taste and smell are distinguished as being pre-eminently the sources of sensation in the strict sense of the term.
***Excerpt from Henry Longueville Mansel, B.d.. Metaphysics or the philosophy of consciousness