Mercury (element)

Mercury, also called quicksilver, is a chemical element in the periodic table that has the symbol Hg (from the Latin hydrargyrum, for watery (or liquid) silver) and atomic number 80. A heavy, silvery, transition metal, mercury is one of five elements that are liquid at or near room temperature (the others are the metals caesium, francium, and gallium, and the nonmetal bromine). more...

Mercury is used in thermometers, barometers and other scientific apparatuses, although the use of mercury in thermometers has been largely phased out in clinical and scientific environments (in favor of alcohol-filled, digital or thermistor-based replacements) in the interests of health and safety due to the toxicity of the element. Mercury is mostly obtained by reduction from the mineral cinnabar. Its high density allows things such as billiard balls to float with less than 20% of their volume submerged.

Applications

Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It is used in some thermometers, especially ones which are used to measure high temperatures (In the United States, non-prescription sale of mercury fever thermometers was banned by a number of different states and localities). Other uses:

• Mercury sphygmomanometers.
• Thimerosal, an organic compound used as a preservative in vaccines and tattoo inks (Thimerosal in vaccines).
• Mercury barometers, diffusion pumps, coulometers, and many other laboratory instruments. As an opaque liquid with a very high density, it is ideal for this role
• The triple point of mercury, -38.8344 °C, is a fixed point used as a temperature standard for the International Temperature Scale (ITS-90).
• In some gaseous electron tubes, mercury arc rectifier
• Gaseous mercury is used in mercury-vapor lamps and some "neon sign" type advertising signs and fluorescent lamps.
• Liquid mercury was sometimes used a coolant for nuclear reactors. However sodium is proposed for reactors cooled with liquid metal, because the high density of mercury requires much energy for circulating the coolant.
• Mercury was once used in the amalgamation process of refining gold and silver ores. The practice is continued by the garimpeiros (gold miners) of the Amazon basin in Brazil.
• Mercury is still used in some cultures for folk medicine and ceremonial purposes which may involve ingestion, injection, or the sprinkling of elemental mercury around the home.
• Alexander Calder built a mercury fountain for the Spanish Pavilion at the 1937 World's Fair in Paris.

Miscellaneous uses: mercury switches, mercury cells for sodium hydroxide and chlorine production, electrodes in some types of electrolysis, batteries (mercury cells), and catalysts, herbicides (discontinued in 1995), insecticides, dental amalgams/preparations and liquid mirror telescopes.

Historical uses: preserving wood, developing daguerreotypes, silvering mirrors, anti-fouling paints (discontinued in 1990), cleaning, and in road leveling devices in cars. Mercury compounds have been used in antiseptics, laxatives, antidepressants, and antisyphilitics. It was also allegedly used by allied spies to sabotage German planes. A mercury paste was applied on bare aluminum, causing the metal to rapidly corrode. This would cause the planes to mysteriously fall apart. In Islamic Spain it was used for filling decorative pools and for fountains .

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