86 Mr. R, Phillips on the [Feb. 



kind of copper ore, to which I am incHned to attribute the 

 variations in the analyses that I have already quoted. 



As a prehminary step, I roasted some of tlie ore until the sul- 

 phur was perfectly expelled ; the residuum was dissolved in 

 nitric acid to saturation. Water added to the solution occasioned 

 no precipitation, nor did muriate or sulphate of soda. From 

 these experiments! conclude that the ore contained neither anti- 

 mony, bismuth, silver, nor lead. A quantity of the ore, without 

 being roasted, was dissolved in nitric acid ; the solution after 

 being treated with nitrate of barytes, gave no precipitate with 

 nitrate of lead ; consequently the ore contains no arsenic. 



In order to determine the proportions in which the sulphur, 

 iron, and copper, exist in the ore, I reduced 120 grains of it to 

 powder, and heated it in a retort with dilute nitric acid, adding 

 muriatic acid towards the end of the operation, to prevent the 

 separation of the peroxide of iron. 



After the complete conversion of the sulphur into sulphuric 

 acid, I found 0*6 of a grain unacted upon ; it consisted of 

 small particles of quartz which had evidently been mechanically 

 mixed with the ore. 



To the solution of the ore, nitrate of barytes was added in 

 excess to precipitate the sulphuric acid. The sulphate of 

 barytes was separated by a double filter ; dried on a sand heat, 

 after being thoroughly washed, it weighed 216*5 grains. Of 

 this, only 211 grains could be removed from the filter, and they 

 lost 4*8 grains by exposure to a red heat in a platina crucible ; 

 consequently ^'b, the quantity left on the filter, would have lost 

 1*25 grains by similar treatment. The whole quantity of ignited 

 sirlphate of barytes amounted, therefore, to 210-45 grains. 



To the filtered solution, after the separation of the sulphate of 

 barytes, sulphate of soda was added to precipitate the excess of 

 barytes employed ; the solution again filtered was treated with 

 ammonia in excess, which precipitated the peroxide of iron. 

 This, after washing and ignition, weighed 24 grains. 



The ammoniacal solution of copper was put into a retort, and 

 evaporated to dryness. The residual mass was dissolved in 

 muriatic acid, and precipitated with excess of potash : the pre- 

 cipitate, which was peroxide of copper, was washed, dried, and 

 ignited ; it weighed 91*6 grains. 



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

 equivalent to 16 of sulphur; 210*45 will, therefore, indicate 

 28*5. According to the same authority, 40 of peroxide of iron 

 contain 28 of metallic iron ; 24 will, therefore, give 16*8 : per- 

 oxide of copper is universally allowed to contain one-fifth of 

 oxygen ; 91*6 \\ill, therefore, give 73*28. It appears, therefore, 

 that this ore consists of 



