COPPER ORES. 307 



What will be ultimately the proceeds of the copper region of Lake 

 Superior, cannot now be fully determined. But there is every prospect 

 that the country will prove boundless in its resources. 



Uses. The metal copper was known in the earliest periods and wag 

 used mostly alloyed with tin, forming bronze. The mines of Nubia 

 and Ethiopia are believed to have produced a great part of the copper 

 of the early Egyptians. Eubaea and Cyprus are also mentioned as 

 affording this metal to the Greeks. It wag employed for cutting- in- 

 struments and weapons, as well as for utensils ; and bronze chisels are 

 at this day found at the Egyptian stone-quarries, that were once em- 

 ployed in quarrying. This bronze, (ehalkos of the Greeks, and <bs of 

 the Romans,) consisted of about 5 parts of copper to 1 of tin, a pro- 

 portion which produces an alloy of maximum hardness. Nearly the 

 same material was used in early times over Europe ; and weapons and 

 tools have been found consisting of copper, edged with iron, indicating 

 the scarcity of the latter metal. Similar weapons have also been found 

 in Britain ; yet it is certain that iron and steel were well known to the 

 Romans and later Greeks, and to some extent used for warlike weapons 

 and cutlery. 



Copper at the present day is very various in its applications in the 

 arts, ft is largely employed for utensils, for the sheathing of ships, and 

 for coinage. Alloyed with zinc it constitutes brass, and with tin it forms 

 bell-metal as well as bronze. 



The best brass contains 2 parts of copper to 1 of zinc ; the proportion 

 of 4 of copper to 1 of zinc, makes a good brass. Pinchbeck contains 

 5 of copper to 1 of zinc ; and tombac and Dutch gold, are other allied 

 compounds. Bath metal consists of 9 of. zinc to 32 of brass. A 

 whitish metal used by the button-makers of Birmingham, and called 

 platina, is made of 5 pounds of zinc to 8 of brass. 



Bronze is an alloy of copper with 7 to 10 per cent, of tin. This is 

 the material used for cannon. With 8 per cent, of tin, it is the bronze 

 for medals. With 20 of tin, the material for cymbals. With 30 to 33 

 parts of tin, it forms speculum metal, of which the mirrors for optical 

 instruments are made. Lord Rosse used for the speculum of his great 

 telescope, 126 parts of copper to 57-£ parts of tin. 



The brothers Keller, celebrated for their statue castings, used a metal 

 consisting of 91*4 per cent, of copper, 5*53 of zinc, 1*7 of tin, and 137 

 of lead. An equestrian statue of Louis XIV, 21 feet high, and weigh 

 ing 53,263 French pounds, was cast by them in 1699, at a single jet. 



Bell-metal is made of copper, with a third to a fifth as much tin by 

 weight, the proportion of tin varying according to the size of the bell 

 and sound required. The Chinese gong contains 80 parts of copper to 

 20 or 25 of tin ; to give it its full sonorousness, it must be heated and 

 suddenly cooled in cold water. 



Sheet copper is made by heating the copper in a furnace and rolling 

 it between iron rollers. Copper is also worked by forging and casting. 

 In casting, it will not bear over a red heat without burning. 



How did the ancients use copper 1 What is the proportion of alloy 

 in the ancient bronze ' 



