Pure Silver
Silver is a chemical element in the periodic table that has the symbol Ag (from the traditional abbreviation for the Latin Argentum) and atomic number 47. A soft white lustrous transition metal, silver has the highest electrical and thermal conductivity of any metal and occurs in minerals and in free form. This metal is used in coins, jewelry, tableware, and photography.
Pure silver also has the highest thermal conductivity, whitest color, the highest optical reflectivity (although it is a poor reflector of ultraviolet), and the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for the effect of light upon them. This metal is stable in pure air and water, but does tarnish when it is exposed to ozone, hydrogen sulfide, or air with sulfur in it.
Silver has been used for thousands of years for ornaments and utensils, for trade, and as the basis for many monetary systems. Its value as a precious metal was long considered second only to gold. In Ancient Egypt and Medieval Europe, it was often more valuable than gold.
Associated with the moon, as well as with the sea and various lunar goddesses, the metal was referred to by alchemists by the name luna.
One of the alchemical symbols for silver is a crescent moon with the open part on the left. Silver itself is not toxic but most of its salts are poisonous and may be carcinogenic.
Compounds containing silver can be absorbed into the circulatory system and become deposited in various body tissues leading to the condition called argyria which results in a permanent grayish pigmentation of the skin and mucous membranes. Although this condition does not harm a person's health, it is disfiguring. Ingestion of colloidal silver and silver compounds can lead to argyria.
Silver plays no natural biological role in humans.
The possible health effects of silver are a subject of dispute. Silver has germicidal effects and kills many microbial organisms in vitro without causing noticeable harm to more complex life-forms. Hippocrates, the father of modern medicine, wrote that silver had beneficial healing and anti-disease properties. Various kinds of silver compounds are sold as remedies for a variety of diseases. However, no clinical study has yet demonstrated a therapeutic use for silver as an antibiotic in vivo.
Silver compounds are used to accelerate healing in burn victims.
Silver-ions and silver compounds show a toxic effect on some bacteria, viruses, algae and fungi because of the oligodynamic effect which is typical for heavy metals. Copper is active against algae while silver is active against bacteria primarily due to silver's activity in the absorption of oxygen causing bacteria to oxidize on contact.