272 



ON THE NATIVE SULPHURETS OF IRON 



Its appearance 

 and habitudes* 



tioncd precautions, and obtained three hundred and eighteen 

 grains of fulphuret. When taken out of* the retort it wai 

 mixed with a new dofe of fulphur, and heated befide another 

 which contained crude pyrites. The fuper-abundant fulphur 

 parted in diflillation, and the retorts were kept for an hour at 

 the fame heat. The refult of this operation was an artificial 

 pyrites, weighing three hundred and feventy-eight grains. It 

 was pulverulent, which proved that it had retained no more 

 fulphur than its attraction could take up. 



Its colour was no longer blackifh, but greenifli yellow. 

 When treated with the acids, its habitudes were precifely the 

 fame as thofe of the regenerated pyrites ; and laitly, it dif- 

 fered from the native pyrites only by the want of that den- 

 fity which the latter received from their humid cryftallization. 

 Confequences. 

 From the foregoing facts it follows, that iron can fix fixty 

 per cent, of fulphur by a confiderably elevated temperature. 

 This proportion conftitutes iron fulphurated to the minimum. 

 By a lower heat it can alfo attract a quantity which is equal 

 to the half of this weight; and this refult is iron fulphurated 

 to the maximum, or with ninety parts of fulphur. If this 

 Iaft combination be expofed to the temperature which formed 

 the firft, it returns to that Hate; that is to fay, it returns 

 fulph. + 9 iron, to the minimum of fulphuration, by giving out all the fulphur 

 it was capable of fixing above the proportion of fixty parts for 

 each quintal of iron. Iron fulphurated to the maximum is the 

 pyrites, and poflefles all its properties excepting denfity. 

 Pyrites reduced In order to render the highly-fulphurated iron fit for afFord- 

 £y Lat^khTon * n & hidrogen, it need only be heated with half its weight of 



Recapitulation 

 of the fafts, 

 with o b fcrva- 

 tion s. 



Sulphuret at 

 the minimum 

 10 fulph. -J- 6 

 iron. 



Sulphuret at the 

 maximum io 



filings, 



filings. 



or by diflillation, To apply pyrites to the fame ufe, the fame treatment may 

 be adopted, or they may be difiilled, in order to deprive them 

 of that portion of fulphur which conftitutes the difference be- 

 tween the fulphuret at the minimum, and that at the maximum. 



not found native. The mineral kingdom has Hot yet prefented iron fulphu- 

 rated to the minimum. In the yellow coppery pyrites, which 

 is a compound of two fulphurets, the iron is always, at the 

 maximum of its iaturation, and accordingly thefe ores refift all 

 acids, except fuch as can oxide the excefs of fulphur. 



I fhewed in my former memoir, that the native fulphuret 

 of copper is ufually found with an excels of fulphur amount- 



Copper in both 

 ftaies ? 



