October 31 - November 3, 2004
Element of the Day
Tuesday, November 2
Anglo-Saxon,
Seolfor; Latin. argentum Silver
is recovered during electrolytic refining of copper. Commercial fine silver
contains at least 99.9% silver. Purities of 99.999+% are available commercially. While silver itself is not considered to be toxic, most
of its salts are poisonous. Silver compounds can be absorbed in the circulatory
system and reduced silver deposited in the various tissues of the body. A
condition, known as argyria, results with a grayish pigmentation of the skin and
mucous membranes. Silver has germicidal effects and kills many lower organisms
effectively without harm to higher animals.
Discovered by: Silver has been known since ancient times. Slag dumps in Asia Minor and on islands in the Aegean Sea indicate that man learned to separate silver from lead as early as 3000 B.C. known since ancient times.
Uses: Sterling silver is used for jewelry, silverware, etc. where appearance is paramount. This alloy contains 92.5% silver, the remainder being copper or some other metal. Silver is of the utmost importance in photography, about 30% of the U.S. industrial consumption going into this application. It is used for dental alloys. Silver is used in making solder and brazing alloys, electrical contacts, and high capacity silver-zinc and silver-cadmium batteries. Silver paints are used for making printed circuits. It is used in mirror production and may be deposited on glass or metals by chemical deposition, electrode position, or by evaporation. When freshly deposited, it is the best reflector of visible light known, but is rapidly tarnished and loses much of its reflectance. It is a poor reflector of ultraviolet. Silver fulminate, a powerful explosive, is sometimes formed during the silvering process. Silver iodide is used in seeding clouds to produce rain. Silver chloride has interesting optical properties as it can be made transparent; it also a cement for glass. Silver nitrate, or lunar caustic, the most important silver compound, is used extensively in photography. Silver for centuries has been used traditionally for coinage by many countries of the world. In recent times, however, consumption of silver has greatly exceeded the output