Because the dissolved particles of sugar are brought in contact with the nerves of taste.
1001. Through what nerves are we made sensible of the contact of sugar with the tip of the tongue?
Through the nerves of feeling, which are abundantly distributed to the tongue to guide it in its controul over the mastication of food.
1002. Why do connoisseurs of wines close their mouths and distend their chins for a few seconds, when tasting wines?
Because they thereby bring the wine in contact with the under surface of the tongue, in which the gustatory nerves chiefly reside.
1003. Why do they also pass the fumes of the wines through their nostrils?
Because flavour, in its fullest sense, comprehends not only the taste, but the odour of a substance; and, therefore, persons of experience attend to both requisites.
The various conditions of taste are defined to be:—
1. Where sensations of touch are alone produced, as by glass, ice, pebbles, &c.
2. Where, in addition to being felt upon the tongue, the substance excites sensation in the olfactory nerves, as by lead, tin, copper, &c.