504 Of the A r s e n i c 



triol, without which it cannot -, as I have fhewn 

 from the Friberg-fchlacken-bade *. 



(5.) Arfenic lodges in pyrites, and effentially in 

 the white fort. This pyrites, and the fmalt-cobald, 

 are here at Friberg the principal forts •, the former 

 is a whitifh fort, confifting of iron, a crude earth 

 and arfenic ; notfo readily found as the other forts, 

 and never under the under-turf earth, nor readily 

 in fquats, but commonly in veins. At Friberg in 

 particular, it breaks near coarfe veins, as mock« 

 lead, fulphur, copper- pyrites and glitter ; parti- 

 culary, it every where accompanies mock-lead : in 

 the Obergeburg it readily lies near Zwitter : befides 

 iron 3 it contains but a very inconfiderable fhare of 

 filver ; it is picked out from among our ores, as 

 being not only unferviceable in our fmekings, but 

 alfo rapacious, or detrimental to the procuring the 

 full yield of metal ; its arfenic, if not well difcharg- 

 ed at firft, manifesting its ill effects not only in the 

 lead and copper works, but alfo in the bufinels of 

 cupellation, befides proving prejudicial to the li- 

 tharge. It is ufually employed for making arfenic, 

 tho' only incidentally with us, on the fcoie of the 

 charges. The arfenic rifes out of it, and cobald, 

 like a white- grey fume, fettling like a white-grey 

 powder in the receptacles prepared for it, as in fo 

 many aludels. The proportion of arfenic in luch 

 pyrites is generally a thiid, and rather over than 

 under : and thus, it exceeds the proportion of ful- 

 phur in the fulphur -pyrites, which at mofb amounts 

 but to a fourth of the other confeituent parts : and 

 thefe proportions are the more to be remarked, as 

 they do not offer only in a few inftances, but are 

 obfeived to hold conftantiy. 



* Breflaw Colleaion, P. 9. 



We 



