FREE ESSAY ON MERCURY

MERCURY

Mercury
Atomic Number: 80
Latin: hydrargyrum "liquid silver"
Atomic Symbol: Hg
Atomic Weight: 200.59
Mercury is the only common metal that is a free-flowing liquid at room temperature. It is
slightly volatile in room temperature and becomes solid when subjected to a pressure of
7640 atmospheres. The metal dissolves in nitric or concentrated sulfuric acid. 
The chief ore is cinnabar; Spain and Italy produce about 50% of the world's supply of the
metal. The commercial unit for handling mercury is the "flask," which weighs about 76
pounds. The metal is obtained by heating cinnabar in a current of air and by condensing
the vapor. The metal is widely used in laboratory work for making thermometers,
barometers, diffusion pumps and many other instruments. It is used in making mercury
vapor lamps, advertising signs, mercury switches and other electronic apparatus. Other
uses are in making pesticides, dental preparations, antifouling paint, batteries and
catalysts. 
The most important salts are mercury chloride (a violent poison), mercurous chloride
(occasionally still used in medicine), mercury fulminate (detonator widely used in
explosives) and mercuric sulfide (a high-grade paint pigment). Mercury is a virulent
poison and is readily absorbed through the respiratory tract, the gastrointestinal tract,
or through unbroken skin. Most human exposure is by inhalation. Air saturated with
mercury at 20 degrees C contains a concentration that exceeds the toxic limit many times.
Mercury vapor diffuses across the alveolar membrane without difficulty. It is lipid
soluble therefore it can get into the blood stream and has a strong affinity for the
central nervous system. The danger increases at higher temperatures thus it's important
that mercury be handled with care. 
Chronic mercury poisoning causes irreversible brain, liver and kidney damage. For
example, Minamata disease was discovered in 1956 and in 1968 it was announced that it was
a pollution disease caused by the Chisso Co. Ltd. The Chisso Company polluted Minamata
Bay of Japan with factory wastewater that contained methyl mercury. The methyl mercury
got into the fish and people of Japan ate the fish and got the disease. The methyl
mercury that entered the body mainly attacked the central nervous system, including the
brain and caused various symptoms including numbness and unsteadiness in the legs and
hands, tiredness, ringing in the ears, narrowing of the field of vision, loss of hearing,
slurred speech, and awkward movements. Some early severe victims of Minamata disease went
insane, became unconscious, and died within a month of the onset of the disease. There
are also victims with chronic symptoms, such as headaches, frequent tiredness, loss of
the senses of smell and taste, and forgetfulness, which are not easily visible but make
daily life difficult. Moreover, there are congenital Minamata disease patients, who were
born with handicaps after being attacked by methyl mercury while in the wombs of their
mothers who consumed polluted fish. No fundamental cure for Minamata disease has yet been
discovered, so treatment consists of attempts to lessen the symptoms and physical
rehabilitation therapy.
Bibliography
Bibliography
Klaassen, Curtis D. Casarett & Doull's Toxicology The Basic Science of Poisons, 1996
McGraw-Hill, p 710
Microsoft Encarta Online Encyclopedia 2000. "Mercury (element)" 
http://encarta.msn.com