silver (Ag) [AS, seolfor] , a whitish precious metal occurring mainly as a sulfide. Its atomic number is 47; its atomic mass is 107.88. It is quite soft and is usually alloyed with small amounts of copper to increase its durability. Silver dissolves readily in nitric acid and is used extensively to produce silver halides used in photographic emulsions. It is frequently associated in small amounts with the ores of zinc, copper, and lead and is used extensively as a component of amalgams of dental fillings and in many medications, especially antiseptics and astringents. Some antiseptics containing silver are mild silver protein and strong silver protein, preparations that render silver colloidal in the presence of protein. Mild silver protein contains 19% to 23% silver. Strong silver protein contains 7.5% to 8.5% silver. Both preparations are used externally as antiseptics and do not have irritating properties. Silver nitrate was once widely used externally as an antiseptic and astringent, especially in the prevention of ophthalmia neonatorum. It has been largely replaced with antibiotic eye drops, such as erythromycin. It is also used as a lubricant on the bearings of radiography tubes. Silver picrate, an ionizable salt of silver, is used in the treatment of trichomoniasis and moniliasis of the vagina.
