MER'CURY, n. [L. Mercurius. In mythology, Mercury is the god of eloquence and of commerce, called by the Greeks Hermes, and his name is said to be formed from merces, or mercor. But in antiquity, there were several persons or deities of this name.]

1. Quicksilver, a metal remarkable for its fusibility, which is so great that to fix or congeal it requires a degree of cold which is marked on Fahrenheit's scale at thirty nine degrees below zero. Its specific gravity is greater than that of any other metal, except platina, gold and tungsten. Under a heat of 660 degrees, it rises in fumes and is gradually converted into a red oxyd. Mercury is used in barometers to ascertain the weight of the atmosphere, and in thermometers to determine the temperature of the air, for which purposes it is well adapted by its expansibility, and the extensive range between its freezing and boiling points. Preparations of this metal are among the most powerful poisons, and are extensively used as medicines. The preparation called calomel, is a most efficacious deobstruent.

2. Heat of constitutional temperament; spirit; sprightly qualities.

3. A genus of plants,the Mercurialis, of several species.

4. One of the planets nearest the sun. It is 3224 miles in diameter, and revolves round the sun in about 88 days. Its mean distance from the sun is thirty seven millions of miles.

5. The name of a newspaper or periodical publication, and in some places,the carrier of a newspaper or pamphlet.

MER'CURY, v.t. To wash with a preparation of mercury.