of Jirthrey , in StirUngsJnre, 107 



7. To ascertain the quantity of sulphur and arsenic, IQO 

 grains of the purified ore, in the slate of a fine powdar, 

 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 cutoff, the ore was found 

 in a round solid mass, having the metallic lustre, a con- 

 choidal fracture, and the colour and appearance of varie- 

 gated copper-ore. It had lost 16 grains of its weight. 



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

 ish-brown substance, like melted sulphur. It weighed 

 12*6 grains. Thus, there was a loss of 3*4 grains. As the 

 tube was long, this loss can scarcely be ascribed to sulphtir 

 driven off. I rather consider it as water. For towards the 

 beginning of the 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 digestion in muri- 

 atic acid, cannot be determined. 



9. When the 12*6 grains of yellowish brown matter de- 

 tached from the tube were digested in hot potash-ley, the 

 whole was dissolved, except a fine blackish powder, which 

 weighed one grain, and was arsenic. The dissolved por- 

 tion 1 considered as sulphur. 



10. The potash solution, being mixed with nitric acid, 

 four grains of sulphur fell. The remaining 7*6^ grains must 

 have been converted into sulphuric acid, by the action of 

 the nitric acid. Accordingly, muriate of barytes occasioned 

 a copious precipitate. 



11. The 84 grains of roasted ore being reduced to a fine 

 powder, mixed with half their weight of pounded charcoal, 

 and roasted a second time in a glass-tube, one grain of sul- 



hur sublimed. But the tube breaking before the roasting 

 ad been continued long enough, the process was com- 

 pleted in a crucible. The roasted ore weighed 70 grains. 



12. From the preceding analysis, we learn that the conj 

 fttituents of the Airthrcy ore are as follows: 



I 



1000 



If 



