Ac"id , n.
1. A sour substance.
2.
(Chem.) One of a class of
compounds, generally but not always distinguished by their sour taste, solubility in water, and
reddening of vegetable blue or violet colors. They are also characterized by the power
of destroying the distinctive properties of
alkalies or bases, combining with
them to form salts, at the same time
losing their own peculiar properties. They all contain hydrogen, united with a
more negative element or radical, either alone, or more generally with oxygen, and take their names from this negative element or radical. Those which contain no oxygen are
sometimes called hydracids in distinction from the others which are called oxygen acids or
oxacids.
&fist; In certain cases, sulphur, selenium, or tellurium may take the
place of oxygen, and the corresponding
compounds are called respectively sulphur
acids or sulphacids, selenium acids, or tellurium acids. When the hydrogen of an acid is replaced by a positive element or radical, a
salt is formed, and hence acids are sometimes named as salts of hydrogen; as hydrogen nitrate for nitric acid, hydrogen sulphate for sulphuric acid, etc. In the old chemistry the name acid was applied to the oxides of the negative or nonmetallic elements, now sometimes called
anhydrides.
Ac"id (&?;), a. [L. acidus sour, fr. the root ak to be sharp:
cf. F. acide. Cf. Acute.]
1. Sour, sharp, or biting to
the taste; tart; having the taste of
vinegar: as, acid fruits or liquors. Also fig.: Sour- tempered.
He was stern and his
face as acid as ever.
A.
Trollope.
2. Of or pertaining to an acid; as, acid reaction.
Hear it pronounced