144 ON METALLIC SULPHURETSi 



II. Examination Jbr the sulphur. 



Dissolved in 1. Having dissolved 5 gr. of iron pyrites in nitromuriatic 



aqua regia and ^^^j^ ^^,j^|^ ^j^^ assistance of heat, I dropped into the solution 



precipnated by _ _ ' ^\ 



muriate of ba- muriate of barytes, till no more precipitate was formed. 



rytes to ascer- 'jjjg sulphate of barvtes subsided to the bottom of the ves- 



tain the quan- ' 



tity ofiLilphui-o sel ; and, having poured off the clear liquor, I added some 



distilled water, in order to wash off any foreign salts. I col- 

 lected the sulphate on a filter. Having dried it, first with 

 a gentle heat, increased afterward to redness, and burned 

 the filter separately, I found the weight of the sulphate of 

 barytes, deducting that of the ashes of the filter, was 19*1 

 gr., or 382 to 100 of pyrites. 



2. It might be suspected, that the preceding result was 

 too small, on account of the state of ebullition in which I 

 had kept the solvent, which might have carried off in vapour 

 a portion of the sulphuric acid formed. I thought it right 

 therefore, to make another experiment, employing a more 

 moderate heat. 

 Treated with Accordingly I treated 2*5 gr. of the same pyrites with di- 

 Sfn^a gintle ^"^^"^ nitric'acid, heating it gently. The whole of the sul- 

 heat. phur however was burned except about 0*03 of a gramme 



that remained tuidecomposed. From this solution I ob- 

 tained 9*71 gr., or 388 per cent of sulphur of barytes, cor- 

 responding to 54*3 of sulphur; and, on taking into the ac- 

 count the residuum abovementioned, we shall have 54*8 of 

 Sulplinr in a hundred parts. 



This result I consider as more accurate than the preced- 



0-55of sul- The experiments I have related clearly show, that the 



phur. sulphuret of iron analysed contained about 45 per cent of 



metallic iron, and between 54 and 55 per cent of sulphur, 

 results which difPer very little from those of Mr. Hatchett. 

 It is difficult then to conceive, that iron pyrites contain 

 oxigen, and the quantity corresponding to all the mistakes 

 that could possibly have taken place cannot be many hun- 

 dredths. 



Component 



