110 Native Copper, Ores of Copper, and other Minerals. 



Red oxide of copper, - - - - . 82.52 



Silica, - - - - 17.41 



Oxide of iron, , _ « -trace. 



99.93 

 But it is seldom that specimens of even this degree of purity 

 can be. obtained, and they are found only ia small quantities. 



Compound of Carbon and Oxide oi' Copper. — Associated with 

 the red oxide of copper, there is often found at New Brunswick a 

 dark earthy substance, which is quite friable, and is easily crushed 

 into grains between the fingers. But it sometimes' also occurs in 

 separate veins of from half an inch to two inches in width. On 

 examining the mass with a magnifier, small black shining par- 

 ticles are seen diffused through it. At first I thought, from the 

 association, that they might be black oxide of copper ; but upon 

 trial, I found the black particles to be carbon, probably anthra- 

 cite. When a portion of this aggregate is heated' in the flame 

 of an alcohol lamp, it soon begins to glow, and it continues red 

 hot until a part of the carbon is consumed. This, I suppose, is 

 owing to the oxygen of the oxide of copper. During the com- 

 bustion, no odor was observed. Thrown into red hot nitrate of 

 potash, this compound burns, and loses about half its weight. 

 Heated to 300° or 400° P., it loses seventeen per cent, of its 

 weight, which is probably caused by the driving out of the 

 water which it contains. 



A portion of this substance, after being ignited, was treated 

 with nitric acid. The residuum, amounting to twenty five per 

 cent., was found to be silica. The solution was subjected to 

 the action of sulphuretted hydrogen, and to the clear liquor after 

 filtration ; ammonia was added to precipitate the oxide of iron. 

 The composition is as follows : 



Oxide of copper, - - - 17.50 



Oxide of iron, _ _ _ 5.0O 



Carbon, _ _ _ _ 35.50 



Silica, - - - - 25.00 



Water, . - - - 17.00 



100.00 

 The carbon and sihca being mechanically mixed with the ox- 

 ide of copper, the above proportions are very variable. It is a fact 



