Posts

Showing posts from August, 2011

Silver

Image
Silver whose atomic no is 47 and symbol is Ag has been very popular in jewellery for a very ancient time. Its medicinal uses are also from history. Silver ions and silver compounds show a toxic effect on some bacteria, viruses, algae and fungi, typical for heavy metals like lead or mercury, but without the high toxicity to humans normally associated with these other metals. Its germicidal effects kill many microbial organisms in vitro , but testing and standardization of silver products is difficult. Hippocrates , the "father of medicine" wrote that silver had beneficial healing and antidisease properties, and the Phoenicians stored water, wine, and vinegar in silver bottles to prevent spoiling. In the early 20th century, people would put silver coins in milk bottles to prolong the milk's freshness. Its germicidal effects increased its value in utensils and as jewellery. The exact process of silver's germicidal effect is still not entirely understood, although...

Chromium

Image
Chromium is a chemical element which has the symbol Cr and atomic number 24, first element in Group 6 . It is a steely-gray, lustrous , hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable. It is found primarily in two forms: 1) trivalent (chromium 3+), which is biologically active and found in food, and 2) hexavalent (chromium 6+), a toxic form that results from industrial pollution. This fact sheet focuses exclusively on trivalent (3+) chromium Trivalent chromium is found in a wide range of foods, including: whole-grain products, processed meats, high-bran breakfast cereals, coffee, nuts, green beans, broccoli, spices, and some brands of wine and beer. Most fruits and vegetables and dairy products only contain low amounts. Most of the chromium in people's diet comes from processing or storing food in pans and cans made of stainless steel, which can contain up to 18% chromium. The amount of chromium in the body can...