266 ANALYSIS of a COPPER ORE 



5. The liquid, thus freed from arfenic acid, was mixed with 

 an excefs of ammonia. It afTumed a deep blue colour, while a 

 brown matter precipitated. It was feparated by the filter, and 

 being dried, drenched in oil, and heated to rednefs, it was to- 

 tally attracted by the magnet. It weighed 45.5 grains, and 

 was iron. 



6. The ammoniacal liquid was neutralifed by fulphuric acid, 

 and the copper thrown down by means of an iron plate. It 

 weighed 17.2 grains. 



7. To afcertain the quantity of fulphur and arfenic, 100 

 grains of the purified ore, in the ftate of a fine powder, were 

 put into the bottom of a coated glafs-tube, and expofed for two 

 hours to a red heat. When the whole was cold, and the bot- 

 tom of the tube cut off, the ore was found in a round folid 

 mafs, having the metallic luftre, a conchoidal fra&ure, and the 

 colour and appearance of variegated copper-ore. It had loft 16 

 grains of its weight. 



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

 brown fubftance, like melted fulphur. It weighed 12.6 grains. 

 Thus, there was a lofs of 3.4 grains. As the tube was long, 

 this lofs can fcarcely be afcribed to fulphur driven off. I ra- 

 ther confider it as water. For towards the beginning of the 

 procefs, drops of water were very perceptible in the tube. 

 "\yhether this water was a conftituent of the ore, or derived 

 from the previous digeflion in muriatic acid, cannot be deter- 

 mined. 



9. When the 12.6 grains of yellowifh brown matter de- 

 tached from the tube, were digefled in hot potafh-ley, the 

 whole was difiolved, except a fine blackifti powder, which 



weighed 



