A'cid. adj. [acidus, Lat. acide, Fr.] Sour, sharp.
Wild trees last longer than garden trees; and in the same kind, those whose fruit is acid, more than those whose fruit is sweet. Bacon's Natural History, № 585.
Acid, or sour, proceeds from a salt of the same nature, without mixture of oil; in austere tastes the oily parts have not disentangled themselves from the salts and earthy parts; such is the taste of unripe fruits. Arbuthnot on aliments.
Liquors and substances are called acids, which being composed of pointed particles, affect the taste in a sharp and piercing manner. The common way of trying, whether any particular liquor hath in it any particles of this kind, is by mixing it with syrup of violets, which it will turn of a red colour; but if it contains alkaline or lixivial particles, it changes that syrup green. Quincy.