co?itahied in Ydllozu Copper Or?. 13^ 



Having roafted four hundred grains of the ore, at a heat 

 proper for keeping it red, in a teft, four hours were required 

 to difengage all the fulphur. There remained a blackifli 

 brown powder compofed of calx of iron and copper. A 

 magnet pluno"ed into this mixed calx, came out covered with 

 particles of iron. 



The yellow copper ore fuftains no fenfible diminution of 

 its weight by torrefaftion ; the fulphur, how-ever, burns, and 

 is exhaled in fulphureous acid ; but the melals becoming cal- 

 cined,. increafe in weight by the acid and water which thev 

 abforb : the fulphur furniihes acid, and the air decompofed 

 furniflies water. 



I determined the quantity of iron contained in the yellow- 

 copper ore, bv putting a quintal of it, after being torrefied, 

 to digeft cold in volatile alkali. I added of it to this calx 

 till it was no longer coloured blue : the iron remained at the 

 bottom of the veiTel under the form of a blackifli powder, 

 which, when walhed and dried, was fufceptible of being at- 

 tratted bv the magnet. This iron was equal in weight to 

 one-half of the ore which I had put to digeft; with the vola- 

 tile alkali. 



I difengaged the fulphur from the yellow copper ore by 

 diftilling it with two parts of concentrated vitriolic acid : 

 there pafTed fulphureous acid, and at the fame time the ful- 

 phur was fublimated of a citron-yellow colour, and condenfed 

 in the neck of the retort. When detached, wafhed, and 

 ■weighed, it amounted to a fifth part of the ore. This pro- 

 portion is the fame as that of the fulphur, which ferves to 

 mineralife antimony, bifmuth, and cobalt. 



The refiduum of the diftillation of the yellow copper ore 

 and vitriolic acid having been wafhed, filtered, and evapo- 

 rated, produced in the firll infiance martial vitriol (or fulphat 

 of iron) in beautiful rhombs; ;t had a blueilh tint, arifing 

 from the copper. 



The yellow copper ore may be decompofed by the nitric 

 acid at twenty-fix degrees, which difTolves with effervefcence 

 the copper and the iron, and affumes a beautiful green co- 

 lour. Nitrous acid mujl be repeatedly digcfted over the 

 popper ore till it no longer become coloured, and imtil the 



fulphu^^ 



