Mer"cu*ry (?), n. [L. Mercurius;
akin to merx wares.] 1. (Rom. Myth.)
A Latin god of commerce and gain; -- treated by the poets as
identical with the Greek Hermes, messenger of the gods, conductor of
souls to the lower world, and god of eloquence.
2. (Chem.) A metallic element mostly
obtained by reduction from cinnabar, one of its ores. It is a heavy,
opaque, glistening liquid (commonly called quicksilver), and
is used in barometers, thermometers, etc. Specific gravity 13.6.
Symbol Hg (Hydrargyrum). Atomic weight 199.8. Mercury has a
molecule which consists of only one atom. It was named by the
alchemists after the god Mercury, and designated by his symbol,
☿.
☞ Mercury forms alloys, called amalgams, with many
metals, and is thus used in applying tin foil to the backs of
mirrors, and in extracting gold and silver from their ores. It is
poisonous, and is used in medicine in the free state as in blue pill,
and in its compounds as calomel, corrosive sublimate, etc. It is the
only metal which is liquid at ordinary temperatures, and it
solidifies at about -39° Centigrade to a soft, malleable, ductile
metal.
3. (Astron.) One of the planets of the
solar system, being the one nearest the sun, from which its mean
distance is about 36,000,000 miles. Its period is 88 days, and its
diameter 3,000 miles.
4. A carrier of tidings; a newsboy; a
messenger; hence, also, a newspaper. Sir J. Stephen.
"The monthly Mercuries." Macaulay.
5. Sprightly or mercurial quality; spirit;
mutability; fickleness. [Obs.]
He was so full of mercury that he could not fix
long in any friendship, or to any design.
Bp.
Burnet.
6. (Bot.) A plant (Mercurialis
annua), of the Spurge family, the leaves of which are sometimes
used for spinach, in Europe.
☞ The name is also applied, in the United States, to certain
climbing plants, some of which are poisonous to the skin, esp. to the
Rhus Toxicodendron, or poison ivy.
Dog's mercury (Bot.), Mercurialis
perennis, a perennial plant differing from M. annua by
having the leaves sessile. -- English mercury
(Bot.), a kind of goosefoot formerly used as a pot herb; -
- called Good King Henry. -- Horn
mercury (Min.), a mineral chloride of mercury,
having a semitranslucent, hornlike appearance.