Here is a brief description of mercury.
Mercury is the only common metal liquid at ordinary
temperatures. Mercury is sometimes called
quicksilver. It rarely occurs free in nature and is
found mainly in cinnabar ore (HgS) in Spain and Italy.
It is a heavy, silvery-white liquid metal. It is a
rather poor conductor of heat as compared with other
metals but is a fair conductor of electricity. It alloys
easily with many metals, such as gold, silver, and tin.
These alloys are called amalgams. Its ease in
amalgamating with gold is made use of in the recovery of
gold from its ores.
The most important salts are mercuric chloride HgC12
(corrosive sublimate - a violent poison), mercurous
chloride Hg2Cl2 (calomel,
occasionally still used in medicine), mercury fulminate
(Hg(ONC)2, a detonator used in explosives),
and mercuric sulphide (HgS, vermillion, a high-grade
paint pigment).
Organic mercury compounds are important - and
dangerous. Methyl mercury is a lethal pollutant found in
rivers and lakes. The main source of pollution is
industrial wastes settling to the river and lake
bottoms.
As mercury is a very volatile element, dangerous
levels are readily attained in air. Mercury vapour
should not exceed 0.1 mg m-3 in air. Air saturated with
the vapour at 20°C contains mercury in a concentration
far greater than that limit. The danger increases at
higher temperatures. It is therefore important that
mercury be handled with care. Containers of mercury
should be securely covered and spillage should be
avoided. Mercury should only be handled under in a
well-ventilated area. If you are in possession of any
mercury you are advised to contact a properly qualified
chemist or public health laboratory for its safe
disposal. (Does this include the elemental mercury
contained in dental amalgam fillings?)
Small amounts of mercury spillage can be cleaned up
by addition of sulphur powder. The resulting mixture
should be disposed of carefully.
Strange Matter cartoon included by Nick Kim at the
University of Waikato, New Zealand.
Isolation
Here is a brief summary of the isolation of mercury.
The physical appearance of mercury is well known
because of its use in many thermometers. It was common
to demonstrate the formation of mercury in the
laboratory by heating mercury sulphide (cinnabar, HgS)
but this is strongly discouraged today because of the
toxicity of mercury vapours. Don't do it! However, this
method forms the basis of commercial extraction. The
prepared cinnabar ore is heated in a current of air and
the mercury vapour condensed.
HgS + O2 (600°C) Hg (l) + SO2
(g)
The crude mercury is then washed with nitric acid and
treated with air in order to remove impurities as oxides
or into solution. Further purification is achieved by
distillation at reduced pressure.
WebElementsTM, the periodic table on the WWW
URL: http://www.webelements.com/
Copyright 1993-2000 Mark Winter
[The University of Sheffield and WebElements Ltd, UK]
Document modification date: 10 July 2000
http://siri.uvm.edu/msds2/mf/cards/file/0056.html
Dental
Information 
