from the Pyrites; 309 



powdery heap, are to be called in aid ; and thefe 

 failing, I know not further how to advife, when 

 you would have a vitriol without fire, or the addi- 

 tion of any thing extraneous. 



As to the other inftrument in vitriolifation % name- 

 ly the fire, its relation thereto is fomewhat different 

 from that of the humidity of the air. Such pyrites 

 as fpontaneoufly yield not to the aclion of the air, 

 or too difficultly and flowly, or that mud pre- 

 vioufly be worked for fulphur, are firft, either 

 roafted, burnt, or defulphurated, and this holds, 

 in refpect of the difficulty of vitriolifation, not only 

 of the yellow pyrites ', or our copper- ore, but alfo 

 often of the yellowifh, that is, of many fulphur 

 or iron pyrit<e. But here occurs a difficulty, name- 

 ly, that the burnt pyrites mud generally be thrown 

 on heaps in the open air, though there is alfo a fort, 

 from which, immediately after burning, nay, tho* 

 ftill warm, a vitriol may be elixated. I made trial 

 with ail my pyrites, under the different circumftan- 

 ces of being much and little burnt, put warm and 

 cold into water, but often without procuring any 

 vitriol. 



From the inftance of foffile calamy, which, inv 

 mediately upon burning, nay, whilft ftill warm, 

 yielded not only a good deal of vitriol, but alfo 

 not a iittle alum, I imagined the fame would fuc- 

 ceed equally well, if not better with the pyrites, a3 

 containing the fulphur, confequently the acid of the 

 fulpnur not only fo plentifully, but alfo the metal- 

 earth immediately -, whereas in calamy there is little 

 formal fulphur, confequently, little fulphur- acid ; 

 but it muft firft be, by means of the fire, both ge- 

 nerated and rendered active. The pyrites mixt- 

 work of Geyer, which is properly an iron-ftone in- 



X 3 terfperfed 



