100 ' GOLD. 



It melts at a bright red heat, but cannot be oxi- 

 dated by any furnace, though it may by electricity 

 and galvanism. It does not oxidate in the air ; 

 hence it is so useful in gilding, its beautiful lustre 

 remaining untarnished. 



It is the most ductile and malleable of the me- 

 tals, and may be drawn into the finest wire for gold- 

 lace and other purposes, and may also be hammered 

 into leaves of extreme thinness for gilding. 



Gold is not acted on by any acid except the 

 nitro-muriatic acid and chlorine. From this pro- 

 perty the former was named aqua-regia^ gold being 

 called by the alchemists the king of the metals. 



The solution of gold, called muriate of gold, yields 

 by evaporation crystals of a beautiful yellow co- 

 lour, which, when dissolved in water and precipi- 

 tated by a solution of tin, afford the beautiful pow- 

 der called the purple precipitate qfcassiuSy much 

 used in enamelling. This consists of oxide of gold 

 mixed with oxide of tin. 



If any substance, as a piece of ribband, be dipped 

 into the muriate of gold, and then exposed to a 

 stream of hydrogen gas, the gold will be revived, 

 and the substance covered with it. Some com- 

 bustible bodies attract the oxygen from the solu- 

 tion of gold, and cause it re-appear in its metallic 

 state. Thus, if a piece of charcoal be put into a 

 glass-jar containing a diluted solution of gold, and 

 exposed to the direct rays of the sun, it will soon 

 appear gilt. When ammonia is added to a solution 

 of gold, a yellow precipitate is formed, called ^ful- 

 minating gold, because it has the property of ex- 

 ploding when exposed to heat. 



If to a solution of muriate of gold, sulphuric ether 

 be added, the gold will combine with the ether, 



15 



