OS METALLIC SULPIIURETS. l^^ 



I. Examination for the iron. 



1. I boiled a mixture of nitric and muriatic acids on five Analysed, 

 grammes [77 grs.] of powdered pyrites. The sulphur was f'^'l^^ "^ aqua 

 completely burned, and the solution was complete, except 



0*01 of a gramme of silex. The oxide of iron precipitated Precipitated by 

 by ammonia and heated red hot weighed 3 '35 gr. : which in- ammonia. 

 dicate, supposing the proportion to be 148 to 100, 2*25 gr. 

 of metallic iron, or 45 per cent. 



2. Another experiment made in the same manner yielded This repeated. 

 me 3'34 gr. of red oxide of iron ; which coincides with the 

 preceding. 



3. I roasted 20 gr. [308 grs.] of the same pyrites. After Roasted, 

 being exposed some hours to a pretty violent heat, the weight 



was reduced to 13*24 gr. : so that 100 left only 66*2. 



Of this residuum I dissolved 5 gr. in nitromuriatic acid. Residuum dis- 

 Muriate of barytes producing no precipitate in this solution, ^"JY^'* ^" ^^"* 

 I concluded, that the roasting had been complete, and the No precipitate 

 pyrites reduced to pure oxide of iron. Besides, on com- 7".^ munateof 

 paring the weight of the residuum of 5 gr. of pyrites, being 

 3'31 gr., with that of the oxide of iron obtained by the ex- 

 periment above, namely 3'34 gr., there can be no doubt, 

 but the whole of the sulphur and sulphuric acid were vola- 

 tilized. This new method of computing the quantity of 

 oxide of iron leaves no doubt respecting the proportion of 

 metal in the pyrites, being equally indicative of 45 per cent 

 of metallic iron. 



4. I fused the roasted pyrites witliout any addition in a Roasted pyrites 

 crucible lined with charcoal, in order to obtain the metal, fi^'sed without 

 The button amounted to 70*2 per cent, without any scorite. 

 Deducting 3 per cent for the carbon combined with it, we 



shall havedS'l of iron from 100 of roasted pyrites, and from 

 100 of pyrites in its native state 45*08 of pure iron. 



From the four experiments here mentioned it follows. Contained 0-45 

 that the sulphuret of iron contains 45 hundredths of me- P^ nieialhc 

 tallic iron ; and I do not think, that any errour can have 

 taken place to the amount of one hundredth. 



II. Examination 



