Mercury

Mercury, or quicksilver, is a dense, silvery chemical element named after the Roman god of commerce and trading. It has fascinated humans for centuries, in part because it is something of an oddity—it is the only metal that remains a liquid at body temperature. Its abbreviation in the periodic table, Hg, is derived from its Greek name, hydrargyrum, which means “water silver.” In German, mercury is called Quecksilber, while in French it is known as mercure, from which the English word is derived.

Mercury is most commonly found in a reddish ore called cinnabar. When the ore is heated, the mercury liquefies and oozes out of the crevices of the cinnabar. The world's largest deposit of cinnabar was located in southwestern Spain in a mine named the Almaden, which is Arabic for “the mine.” Another large deposit, the Idria in Slovenia, has been mined for the last 2,000 years. There are other smaller deposits of cinnabar in China and Latin America. The New Almaden and New Idria Mines in California are the largest deposits of cinnabar in the United States, though it has also been mined in Oregon, Nevada, and Texas. Mercury mining has decreased, due in part to depleting sources of cinnabar, but also to an increased awareness of its toxicity. Today, most of the world's mercury comes from mines in China, Kyrgyzstan, Spain, and Tajikistan.

For centuries humans used mercury for a variety of cosmetic, medicinal, and technological purposes. The Chinese used mercury as early as 2000 b.c.e. and evidence suggests the Egyptians used it about 500 years later. Native Americans in California decorated their bodies with red cinnabar pigment, but because it often burned their skin, they claimed the mines from which it came contained evil spirits.

During the Middle Ages, alchemists thought quicksilver had the ability to turn objects into gold, while medical doctors believed mercury could cure humans of a variety of maladies. The ancient Greeks used mercury in ointments, while England's Dr. Thomas Dover (1660–1743) was known as the Quicksilver Doctor because he commonly prescribed mercury to patients suffering from everything from “apoplexy to worms.” By the 19th century, doctors commonly mixed calomel and “blue mass pills” using mercury to treat diverse maladies from syphilis to tuberculosis and gastrointestinal disorders.

Today, medicines containing mercury are typically considered poisonous; however, mercury can still be found in some over-the-counter medications such as antiseptics, eye drops, and nose spray. In recent years, legislative efforts in both the United States and the European Union (EU) have tried to reduce the amount of mercury in such medications, though mercury amalgams are commonly used in modern dentistry.

Mercury was once an indispensable element in gold and silver mining operations. In 1557 the Patio process was devised to separate silver from ore. Later a more involved stamping and amalgamation process was invented to separate gold and silver from quartz. When gold was discovered in California in 1848, the demand for mercury greatly increased.

Scientists experimented with mercury and by 1643 Evangelista Torricelli invented the barometer; Gabriel Fahrenheit invented the thermometer in 1714. Edward Charles Howard found a military use for mercury in 1799. Howard dissolved mercury in nitric acid and alcohol, forming a crystallized substance called mercury fulminate. When he struck the crystals, it caused a small explosion. Mercury fulminate was used as a primer to detonate gunpowder in cartridges and shells. At the outset of the American Civil War, mercury fulminate was an essential ingredient in warfare.

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