taken in large quantities.  Nobody wishes to drink nitric acid by the quart.  The first business of this part of the tongue is, therefore, to warn us emphatically against caustic substances and corrosive acids, against vitriol and kerosene, spirits of wine and ether, capsicums and burning leaves or roots, such as those of the common English lords-and-ladies.  Things of this sort are immediately destructive to the very tissues of the tongue and palate; if taken incautiously in too large doses, they burn the skin off the roof of the mouth; and when swallowed they play havoc, of course, with our internal arrangements.  It is highly advisable, therefore, to have an immediate warning of these extremely dangerous substances, at the very outset of our feeding apparatus.

This kind of taste hardly differs from touch or burning.  The sensibility of the tip of the tongue is only a very slight modification of the sensibility possessed by the skin generally, and especially by the inner folds over all delicate parts of the body.  We all know that common caustic burns us wherever it touches; and it burns the tongue only in a somewhat more marked manner.  Nitric or sulphuric acid attacks the fingers each after its own kind.  A mustard plaster makes us tingle almost immediately; and the action of mustard on the tongue hardly differs, except in being more instantaneous and more discriminative.  Cantharides work in just the same way.  If you cut a red pepper in two and rub it on your neck, it will sting just as it does when put into soup (this experiment, however, is best tried upon one’s younger brother; if made personally, it hardly repays the trouble and annoyance).  Even vinegar and other acids, rubbed into the skin, are followed by a slight tingling; while the effect of brandy, applied, say, to the arms, is gently stimulating and pleasurable, somewhat in the same way as when normally swallowed in conjunction with the habitual seltzer.  In short, most things which give rise to distinct tastes when applied to the tip of the tongue give rise to fainter sensations when applied to the skin generally.  And one hardly needs to be reminded that pepper or vinegar placed (accidentally as a rule) on the inner surface of the eyelids produces a very distinct and unpleasant smart.

The fact is, the liability to be chemically affected by pungent or acid bodies is common to every part of the skin; but it is least felt where the tough outer skin is thickest, and most felt where that skin is thinnest, and the nerves are most plentifully distributed near the surface.  A mustard plaster would probably fail to draw at all on one’s heel or the palm of one’s hand; while it is decidedly painful on one’s neck or chest; and a mere speck of mustard inside the eyelid gives one positive torture for hours together.  Now, the tip of the tongue is just a part of one’s body specially set aside for this very object, provided with an extremely thin skin, and supplied with an immense number of nerves, on purpose so as to be easily affected by all such pungent, alkaline, or spirituous substances.  Sir Wilfrid Lawson would probably conclude that it was deliberately designed by Providence to warn us against a wicked indulgence in the brandy and seltzer aforesaid.