COPPER. 



carbonates. The extraction of the ores 

 of copper is to be conducted according 

 to the nature of the combination in 

 which they exist. The following process 

 is recommended for the treatment of the 

 sulphurets of copper. The ore is first 

 reduced to powder, and then boiled with 

 five parts of concentrated sulphuric acid. 

 The solution is evaporated to dryness, 

 and the residuum well washed with warm 

 water, to remove all soluble matters. The 

 solution being sufficiently diluted, a plate 

 of copper is immersed in it, which precipi- 

 tates the silver, and afterwards a plate of 

 iron to precipitate the copper. It is boil- 

 ed with the plate of iron till no farther 

 precipitate takes place. The copper 

 which is thus obtained is dried with a 

 gentle heat, so that it may not undergo 

 oxidation. It is supposed that the cop- 

 per is mixed with iron ; the whole may 

 be dissolved in nitric acid; and the pro- 

 cess is again repeated by introducing the 

 plate of iron. In this way it is easy to 

 discover the quantity of copper in the 

 sulphurets of this me'tal. 



Copper is a very brilliant metal, of a 

 fine red colour, differing from every other 

 metallic substance. The specific gravity 

 of copper is 8.58. When it is hammered 

 it acquires a greater density. It posses- 

 ses a considerable degree of hardness 

 and some elasticity. It is extremely mal- 

 leable, and may be reduced to leaves so 

 fine, that they may be carried about by 

 the wind. It has also a considerable de- 

 gree of ductility, intermediate, according 

 to Guyton, between tin and lead. The 

 tenacity of copper is also very great. A 

 wire .078 of an inch in diameter will sup- 

 port a height, without breaking, equal to 

 more than 300/6s. avoirdupois. Copper 

 has a peculiarly astringent and disagree- 

 able taste. It is extremely deleterious, 

 when taken internally, to the animal 

 economy, and indeed may be considered 

 as a poison. It is distinguished by a 

 peculiarly disagreeable odour, which it 

 communicates to the hands by the slight- 

 est friction. Copper does not melt till 

 the temperature is elevated to a red 

 heat, which is about 27 Wedgwood, or 

 by estimation 1450 Fahrenheit. When 

 it is rapidly cooled after fusion, it assumes 

 a granulated and porous texture ; but if 

 it be cooled slowly, it affords crystals in 

 quadrangular pyramids, or in octahe- 

 drons, which proceed from the cube, its 

 primitive form. When the temperature 

 is raised beyond what is necessary for 

 its fusion, it is sublimed in the form of 

 visible fumes. When copper is exposed 



VOU IV 



to the air, especially if it be humid, it is 

 soon deprived of its lustre. It tarnishes, 

 becomes of a dull brown colour, 'which 

 gradually deepens till it is converted into 

 that of the antique bronze, and at last is 

 covered with a shining gre< n crust, which 

 is well known under' the name of verdi- 

 gris. This process is the oxydation of the 

 metal by the absorption of oxygen from 

 the atmosphere ; and it is promoted and 

 accelerated, either by being moistened 

 with water, or by the water which ex- 

 ists in the atmosphere. As this oxide 

 is formed, the carbonic acid of the at- 

 mosphere combines with it, so that it is to 

 be considered as a mixture of oxide and 

 carbonate of copper. But when copper 

 is subjected to a strong heat, the oxida- 

 tion proceeds more rapidly. If a plate of 

 copper be made red hot in the open air, 

 it loses its brilliancy, becomes of a deep 

 brown colour, and the external layer, 

 which is of this colour, may be detached 

 from the metal. This is the brown oxide 

 of copper This oxide may be obtained 

 by immersing a plate of red-hot copper 

 into cold water. The scales which arc 

 formed on the surface fall off by the sud- 

 den contraction of the heated copper. 

 This may be repeated till the whole is 

 converted into this oxide. The copper 

 in this state is in the highest decree of 

 oxidation. The component parts of this 

 oxide are, 



Oxygen 

 Copper 



25 

 75 



100 



There are, however, different oxides ; 

 copper combines with a smaller propor- 

 tion of oxygen, forming an oxide of an 

 orange colour. This is the oxide of cop- 

 per with the smaller propor.ion of oxy- 

 gen. The component parts of this oxide, 

 according to Mr. Chenevix, are, 



Oxygen 

 Copper 



11.5 



88.5 



100.0 



This oxide changes colour the moment 

 it is exposed to the air, by the absorption 

 of oxygen, for which it has a very string 

 affinity. There is no action between 

 azote, hydrogen, or carbon, and copper. 

 Phosphorus readily combines with cop- 

 per, and forms witluta phosphuret, which 



H 



