ANALYSIS OF A GRAY COPPER ORE. n £Q 



jind was almost entirely sulphate of barytes. No traces of 

 suijihate of lead, or of oxide of antiiiiony could be de- 

 tected in it by the blow pipe. ' 



3. The three acid solutions being mixed together, no No silver in ^t. 

 cloudiness appeared, nor was any change produced; a 



proof that the pre contained no silver. 



4. The solution^ being evaporated nearly to dryness, was 

 diluted with water, and precipitated by rauviate of barytes. 

 By this means, the sulphuric and arsenic acids, which had 

 been formed during the long continwed action of the nitric 

 acid on the ore, and the presence of which had been indi- 

 cated by reagents, were thrown down ; for nitrate of lead, 

 added to the residual liquid, occasioned no precipitate; u 

 proof that no arsenic acid was present. 



5. The liquid, thus freed from arsenic acid, was mixed Iron. 

 with an excess of ammonia. It assumed a deep blue colour, 

 while a brown matter precipitated. It was separated by 



the filter, and being dried, drenched in oil, and heated to 

 redness, it was totally attracted by the magnet. It weighed 

 45'5 grains, and was iron. 



6. The amraoniacal liquid was neutralised by sulphuric Copper. 

 acid, and the copper thrown down by means of an iron 

 plate,; It^weighed i7'2 grains. 



7. To ascertain the quantity of sulphur and arsenic, 100 Sulphur and 

 grains of the puritied ore, in the state of a fine powder, arseoic, 

 were put into the bottom of a coated glass tube, and ex- 

 posed for two hours to a red heat. When the whole was 



cold, and the bottom of the tube cut off, the ore was 

 found in a round solid mass, havingCthe metallic lustre, a 

 conchoidal fracture, and the colour and appearance of 

 variegated coppefore. It had lost l6 grains of its weight. 



8. The upper part of the tube was coated with a yellow- Sulphur, 

 ish brown substance, like njelted sulphur. It weighed 1-2*6 

 grains. Thus, there was a^ joss of 3*4 grains. As the tube 



was long, this loss can scarcely be ascribed to sulphur 

 driven off. I rather (Consider it as water. For towards the 

 beginning of tiie process, drops of water were very per- 

 ceptible in the tube. Whether this water was a constituent ' 

 of the ore, or derived from the previous digesiion in muri- 

 atic iicid, eapQot be determined. 



9. When 



