|Gold has been bearing money function. Alloys of gold with copper, silver, and other metals are employed in the manufacture of plate, jewellery, and coins. In the British coinage the metal is alloyed with copper, the coins containing 916.6 parts of gold per 1000. This alloy has a lower melting-point than gold, and is harder. In the United Kingdom there are five legal standards for gold wares; 22-carat (containing 22 parts of gold in 24), 18-carat, 15-carat, 12-carat, and 9-carat. |
It is also used in industry in various strengthening and hardening alloys which also helps in gold sparing. The purity of such alloys express the content of actual gold with other metal, copper or silver, as an addition to the alloy (ligature). Gold and platinum alloy is chemically resistant and may be used in chemical and electrical apparatus. Gold compounds are used for toning in photography.
Since ancient ages gold is used in jewelry, ornamentation, in religious and palatial utensils as well as for gold plating. Due to its softness and ductility gold finds application as a decorative material in creating of various effects, from plain yellow polished surfaces with smooth play of highlights to trickish and elegant textural associations with rich effects of light and shade, and for accomplishment of finest filigrane. Gold coloured by alloying with other metals is used with gems, pearls, enamel and niello.
Gold finds use in medicine too as a suspension in oil in water-soluble injections for rheumatic arthritis and lupus erythematosus treatment.
Gold leaf contains 90 to 98 per cent, of gold alloyed with copper and silver. It is employed in gilding. Gold-plating is carried out in a bath of potassium auricyanide with a gold anode, the strength being maintained at about 6.85 grams of gold per litre by addition of auric chloride.
The metal finds application in photographic toning as sodium aurichloride. The chloride is employed in medicine, and in alloys in dentistry. " Purple of Cassius " is useful for colouring glass. Gold lace consists of a silk body with very fine strips of gold twined round the silk.