106 Of //&<? Iron 



again be made to anfwer the magnet, if, by a due 

 fmelting, its metallic fattinefs be again procured 

 to it. All pyrites, without exception, defulphuratcd 

 in clofe veffels, anfwer the magnet equally with 

 fmelted iron, and a genuine iron-ftone. Even the 

 pyrites, that contains copper in no great quantity, 

 is acted on by the magnet \ that holding much as 

 ten, twenty, thirty, and more pounds the quintal, 

 not fo ftrongly, but more or lefs in proportion to 

 the copper it holds \ but the copper predominat- 

 ing in a greater proportion, the virtue of the mag- 

 net proves more weak and effete, or has no effect 

 at all. The magnet alfo exerts fome efficacy on 

 the mijfpickel of Friberg, and the poifon-pyrites of 

 the Obergeburge. 



In order to know what fort, and how much of 

 other metals the magnet can bear, fo as to continue 

 to exert its virtue ; I, by it, after defulphu ration, 

 examined different pyrites-copper- ores, and plainly 

 found it attracted them all, though not within the 

 fame fphere, nor with the fame briiknefs of acti- 

 vity, as it does the pure iron, or poor copper py- 

 rites -, but by it I could not difcover the exact pro- 

 portion of iron and copper in each, and, confe- 

 quently, how much copper the magnet can bear 

 in the iron, without lofing its virtue thereon •, only 

 I obferved a greater efficacy exerted on one fort, 

 as the pyrites of Ilmenau and Sweden, than on 

 thofe from Lorentz- vein, near the Halfebrucke •, 

 thofe from the Kuhfchaft, Kroner, Kayfer Hen- 

 rich, Goflar, &c. in general ; but then 'tis not 

 poflible, in an intelligible manner, to fpecify the 

 particular degree of attraction. Again, I am not 

 fure, whether the pyrita, which here, in refpect 

 of the magnetic virtue, are to be compared toge- 

 ther, have always gone through one and the fame 



degree 



