136 Annhjsis of the viagnetical Pyrites. 



§111. 



From the appearance of those parts of the magnetical py.< 

 rites which have been exposed to the weather, it seems to 

 be liable to oxidizenicnt, but not to vitriolization. 



The specific gravity, at temperature 63*' of Fahrenheit, 

 is 4518. 



When exposed to the blowpipe, it eiiiils a sulphureous 

 odour, and melts into a globule nt-arly black, which is at- 

 tracted by the magnet. 



500 grains, in coarse powder, were exposed, in a small 

 earthen retort, to a red heat, during three hours. By this 

 operation the weight of the powder was vcrv little dimi- 

 nished ; neither was there any appearance of sulphur in 

 the receiver, which, however, smelt strongly of sulphureous 

 acid. 



500 grains of the same wen: put into a flat porcelain cru- 

 cible, which was kept in a red heat, under a nuiffle, during 

 four hours. The powder the n appeared of a dark gray, \\ ith 

 a tinge of deep red, and weighed -ISS-'AO grains. Tl;e loss 

 was therefore 67 -50 = IS'.^O per cent.: but, upon examin- 

 ing the residuum, I fuund that onlv part of the sulphur had 

 been thus separated^ 



The magnetical pvriles, when digested in dilute sulphuno 

 acid, is partially dissolved, with little eftervescencc, although 

 there is a very perceptible odour of sulphuretted hydrogen- 

 Thc solution is of a verv pale green colour. 

 Pure anmionia produced a dark green preripitatc, tending 

 to black ; and prussiate of potash formed a verv pale blue 

 precipitate, or rather a white precipitate mingled witli a 

 small portion of blue. 'I'he whole of the latter, however^ 

 by exposure to the air, gradually assumed tlie usual inten- 

 sity of Prussian blue ; and the blackish <rrcen precipitati, 

 formed by anmionia, became gradualiv ochraccous. These 

 effects, therefore, fully prove, that the iron in the solution 

 was, for the greater part, at the minimum of oxidizcment, 

 so as to form the green sulphate and white prussiate of iron *i 

 and, consequently, that the iron of the mairnetical pyrites is 

 either quite, or very nearly, in the stale of perfect metal. 



This pyrites, when treated with nitric acid of the specific 

 gravity of rs.S, diluted with an equal quantity of water, is 

 at first but little affected; but, when heat is applied, it is 

 dissolved \\ ith much eficrveseence, and discharge of nitrous 

 gas : the effervescence, hovicvcr, is by no means so violent 



* Recbncbes '.ur Ic B!ru d;: Prune, [at M. Proust. Annaks de Chimte, 

 rome xxiii. p. S5. 



as 



