MAGNETIC *]L PYRITES. 269 



The folution was of a pale yellowifo-green colour. With Muriatic felu- 

 prufiiate of potafii it afforded a pale blue precipitate, or rather a 

 white precipitate mixed with blue; and with ammonia it formed 

 a dark blackihVgreen precipitate, which gradually became 

 ochraceous; fo that thefe effects corroborated the conclufions 

 which were founded on the properties of the fulplmric tolution, 

 namely, that the iron contained in the pyrites, is almott, if not 

 quite, in the metallic ftate. 



Other experiments were made; but, as they merely confirm 

 the above obfervations, I (hall proceed to give an account of 

 the analyfis. 



§ IV. 



ANALYSIS OF THE MAGNETICAL PYRITES. 



A. One hundred grains, reduced to a fine powder, were Analyfis. 



•figefted with two ounces of muriatic acid, in a glafs matrafs tlc pyr f tes ^ ei ~ 



placed in a fand bath. The effects already defcribed took digefted in mu- 



place; and a pale yellowith-green folution was formed. The p'artL^fol'ution 



refiduum was then again digefted with two parts of muriatic Refidue treated 



acid mixed with one of nitric acid; and a quantity of pure wn } 1 nltr °- mur » 



. . acid « Some 



fulphur was obtained, which, being dried, weighed 14 grains, fulphur fepa- 



B. The acid in which the refiduum had been digefted, " ted ; 



... . f n ■ • r , • r ■ • , To the add (o- 



was added to the firil muriatic lolution; tome nitric acid was | u tions wasadded 

 alio poured in, to promote the oxidizement of the iron, and fome n ' tric acid 

 thereby to facilitate the precipitation of it by ammonia, which tnen pr eci p . by S 

 was added after the liquor had been boiled for a confiderable ammonia. The 

 time. The precipitate thus obtained was boiled with lixivium foiled with 

 of potafii; it was then edulcorated, dried, made red-hot with afh and then re- 

 wax in a covered porcelain crucible, was completely taken up du " d toblack 

 by a magnet, and, being weighed, amounted to 80 grains. 



C. The lixivium of potafii was examined by muriate of The pota/h lix- 

 ammonia, but no alumina was obtained. mum gave no 



£). To the filtrated liquor from which the iron had been pre- The firft folu- 

 cipitated by ammonia, muriate of barytes was added, until it tion liquor was 

 ceafed to produce any precipitate; this was then digefled with ate of\J y ™s, n ~ 

 i'ome very dilute muriatic acid, was collected, wafhed, and, The fulphateof 

 after expofure to a low red heat for a few minutes in a crucible tainecTfhe'wed 

 of platina, weighed 155 grains. If therefore the quantity of ihe quantity of 

 fulphur, converted into fulphmic acid by the preceding oper- p acid * 

 ations, and precipitated by barytes, be calculated according to 

 the accurate experiments of Mr, Chenevix, thele 155 grains of 



fulphate 



