What is Mercury?

Mary Elizabeth
Mary Elizabeth

Mercury is a metallic element with the atomic number 80 and the symbol Hg, from the Latin hydragyrus, which means “liquid silver.” On the periodic table of elements, it is found in Group 12, just below cadmium, and in Period 6 between gold and thallium. It is referred to as a “transition metal.” It is a heavy element that is liquid at room temperature. Described as silvery-white in color, it is poisonous.

A nurse checking a person's blood pressure with a sphygmomanometer, which contains mercury.
A nurse checking a person's blood pressure with a sphygmomanometer, which contains mercury.

Scientists don't know who discovered mercury, but it was already recognized in ancient times. The extraction process was first described by the Greek philosopher Aristotle (384–322 B.C.). Its name, for the Roman god Mercury, reflects that time period.

Some barometers contain mercury.
Some barometers contain mercury.

This element is often obtained from cinnabar ore. The process by which the vapor is extracted from cinnabar ore is called roasting. It is then condensed in order to collect it in liquid form. Mercury is found mainly in Europe — in Spain, Italy, and the area that was formerly Yugoslavia. About 8,400 tons (7,620 metric tons) per year are produced.

In Alice's Adventures in Wonderland, the Mad Hatter may be said to suffer from mercury poisoning.
In Alice's Adventures in Wonderland, the Mad Hatter may be said to suffer from mercury poisoning.

Mercury has a number of uses. It is the customary liquid in thermometers as well as barometers and sphygmomanometers, and it is used in esophageal dilators, batteries, paint, plastics, and pesticides. Its vapor is also used in lamps, and the element is used in the gold mining industry.

Mercury is typically the liquid used in thermometers.
Mercury is typically the liquid used in thermometers.

This liquid metal is highly toxic. It is associated with birth defects in children and with neurological damage, kidney damage, and blindness upon later exposure.

On the periodic table of elements, Mercury is atomic number 80, and is identified by the symbol Hg.
On the periodic table of elements, Mercury is atomic number 80, and is identified by the symbol Hg.

Today, contaminated fish is one of the main sources of mercury exposure outside of industry. In times past, the element was used in the manufacture of felt hats. Mercury poisoning was, therefore, an occupational hazard of a hatter, leading to the phrase “mad as a hatter” and to the character of the Mad Hatter in Alice’s Adventures in Wonderland by Lewis Carroll, the pen name of Charles Lutwidge Dodgson.

At room temperature mercury exists in liquid form which can be easily absorbed through the skin.
At room temperature mercury exists in liquid form which can be easily absorbed through the skin.

Mercury does have some health uses, however. Its inorganic salts are components of some products that stem the growth of bacteria and fungi. It is also used in hospital labs in urine analysis and in fixatives.

Mercury is very dangerous if allowed to enter the body.
Mercury is very dangerous if allowed to enter the body.
Mary Elizabeth
Mary Elizabeth

Mary Elizabeth is passionate about reading, writing, and research, and has a penchant for correcting misinformation on the Internet. In addition to contributing articles to wiseGEEK about art, literature, and music, Mary Elizabeth is a teacher, composer, and author. She has a B.A. from the University of Chicago’s writing program and an M.A. from the University of Vermont, and she has written books, study guides, and teacher materials on language and literature, as well as music composition content for Sibelius Software.

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Discussion Comments

anon164425

Why would you want to replace mercury in a barometer?

anon25869

Why is it that water is inadvisable to replace mercury in a barometer?

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