Metals. 249 



made to unite by being pressed together by 

 weights. A solid amalgam of lead, and another 

 of bismuth, will become fluid by only being 

 mixed together. 



5th. Copper seems to have been known the 

 earliest of all the metals, except gold and silver. 

 Utensils and weapons were made of it before the 

 method of working iron was discovered. It 

 takes its name from the island of Cyprus, where 

 it was first wrought. It has a disagreeable smell 

 and taste, and is highly malleable, ductile, and 

 tenacious. In a strong heat it emits fumes, 

 and even burns with a green flame of great bril- 

 liancy. 



Copper is of essential use in the arts, both in 

 its metallic state, and with respect to the salts 

 which are formed from it, such as verdigrise, 

 which is an acetate of copper, or copper united 

 with acetic acid, and blue vitriol, which is a sul- 

 phat of copper. 



Copper combines with most of the metals, 

 and its alloys * are important. The gold coin of 

 most countries is alloyed with copper, according 

 to a standard established by law, which is done 

 to render the precious metal harder and more 



* Alloys are mixture? of metals ; the baser metal, and 

 of which there is least in quantity, is called the alloy. Al- 

 loys differ from amalgams in this, that the former are 

 hard, the latter soft. Hence amalgams can only be made 

 with mercury. 



M 5 



