1822.] Yellow Copper Ore, 299 



Analysis, 



I cannot find that crystallized yellow copper ore has ever been 

 subjected to analysis, but the amorphous has been analyzed both 

 by Lampadius and Gueniveau. According to the former, it 

 consists of 



Sulphur 43-70 



Iron 16-57 



Copper 39-73 



100-00 



According to Gueniveau, taking the mean of two analyses, 

 one specimen being from Sainbel, and the other from Baigorry, 

 this ore (omitting a small extraneous admixture) consists of 



Sulphur 36-36 



Iron 33-00 



Copper 30-64 



100-00 



To analyze this ore, I proceeded in the mode described in 

 page 86 of the present volume. One hundred grains reduced 

 to powder were heated in a mixture of nitric and muriatic acid 

 until the whole of the sulphur was acidified. Half a grain of 

 earthy matter was left undissolved ; to the clear solution, nitrate 

 of barytes was added in excess ; and the sulphate of barytes 

 obtained, after washing and drying, weighed 259*3 grains. 



The excess of barytes being separated by sulphate of soda, 

 the clear solution was supersaturated with ammonia so as to 

 dissolve the oxide of copper, and precipitate the oxide of iron ; 

 the latter washed and dried, weighed 46 grains. 



The ammoniacal solution of copper was heated with potash so 

 as to evaporate the whole of the ammonia, and reduce the cop- 

 per to the state of peroxide : this, washed and dried, weighed 

 37-5 grains. 



According to Dr. Thomson, 118 of sulphate of barytes are 

 equivalent to 16 of sulphur; 259-3, therefore, indicate 35*16 : 

 40 of peroxide of iron contain 28 of metallic iron ; 46 will give 

 32*2 ; and as peroxide of copper contains one-fifth of its weight 

 of oxygen, 37-5 are equal to 30 of copper. 



On adding together these products, it will be found that with 

 the earthy matter they make 97-86, leaving a deficiency of 

 2-14 in the 100 parts of ore. 



As this loss is so considerable, I repeated the analysis as far 

 as regards the copper, in which the error was suspected to exist ; 

 but I obtained precisely the same quantity of peroxide as at first, 

 I, therefore, examined the solution of potash with which the 

 oxide of copper had been boiled. This solution was saturated 

 with nitric acid, carbonate of soda was added to it, and a 

 white precipitate was formed, which was blackened by sulphuret- 



