270 ON ** HE Native stjlphurets of irok< 



pofe this fecond dofe of fulphur, which a new attraction Was 

 to add, to that temperature which would conftitute the firfl 

 point of faturation with regard to iron. 



At a given heat the fuper-abundance of fulphur was carried 

 off by diftillation, after which the two retorts being kept an 

 hour longer at the fame temperature, did not exhibit the 

 flighteft vapour of fulphur. 

 Regenerated py- The regenerated pyrites was pulverulent ; a proof that it 

 mes * had retained no portion of fulphur beyond the point of fatura- 



tion, otherwife I fhould have found it in a pafty ftate, having 

 the figure of the retort. 

 Characters. It had refumed the greenilh yellow colour, which is that of 



crude pyrites when pounded, wher#as its tinge was before 

 dull and blackifh like fulphurated iron, which is capable of 

 affording hidrogen. Its weight was found to be five hundred 

 Proportions of and four grains, that is to fay, the diftilled pyrites had re - 

 parts " fumed twenty-fix pounds of fulphur per quintal. 



Obfervations on $y infpecling the former memoir, we fee that the mean 

 to^ro^thaube P r °du& of two difKUations, each confifting of four hundred 

 artificial pyrites grains of pyrites, was three hundred and eighteen for the re- 

 thfnati™!* 3 udlle > and ieventy-eight for the fulphur, to which mull be 

 added three or four for what was carried away by the gas, fo 

 that in the quintal we have feventy-nine and a half refidue, and 

 twenty and a half fulphur. According to this report, four hun- 

 dred grains of the refidue, or diftilled pyrites, ought to have 

 taken only ninety-eight and a fraction of fulphur, whereas the 

 refult of our experiment gives one hundred and four. The 

 difference being no more than one and half per quintal, may 

 be afcribed to the inaccuracy of experiment, as well as the 

 nature of the pyrites, which is not an homogeneous combina- 

 tion ; for befides the clay and the fand, it often contains a 

 fmall portion of oxide of iron, which may have caufed the 

 fixation of a fomewhat greater quantity of fulphur than the 

 lofs it fuffered by diftillation. 

 Trial of the re- I afterwards examined my regenerated pyrites with a ful- 



generated pyrites pi iur ic acid of ten degrees by the areometer of .Baum6, which 

 by acids: which r ., ..,„ , , ,.„?,, . . ..<• , T . . . 



did not diflblve acid diflolves the diftilled pyrites very well ; but I obtained 



lU . only a. few ounces of fulphurated hidrogeu. I afterwards 



heated the mixture ; it afforded a flight portion of gas, after 

 which the pyrites remained without alteration, Long conti- 

 nued boiling was ineffectual for faturating my acid. 



With 



