?**& PYRITE"£ 2,%? 



(2^1 find metals better fitted for additions for 

 pyrites, and thefe not fo much in their metallic as 

 earthy form, fo they be otherwife adapted to the 

 fubjeft. 



And, (3J Earths feem of more importance 

 than we commonly imagine, from the prejudice 

 of confidering them only as dead, inefficacious bo- 

 dies : for, tho' we may not always allow them ac^ 

 tivity, yet a paflive receptibility we often may. 



I know of earths, not only devoid of all gold 

 or filver, but of any other metal, yet combined 

 with pyrites, yields filver in a proportion never ta 

 be found in pyrites alone. There are earths, looked 

 upon as dead and effete, which in obvious circum- 

 ftances, particularly phofphorus, manifeft the great- 

 eft degree of activity. What are falts other than 

 productions from earth, only that they appear not 

 in their faline form in all operations : and falts and 

 earths are ever mutually convertible •, falts turning 

 again to earth, as is a known cafe. And M. Ro- 

 finus of Munden fent me a white cryftalline fait, 

 greatly refembling a Glauber's or an Epfom fait, 

 and prepared from a fort of ftone, without the ad- 

 dition of any faline matter : which feems to be 

 confirmed, from obferving, that mineral bodies, 

 manlfefting nothing faline, as bifmuth ore and co- 

 bald, much more alum-Jhiver, do barely by means 

 of the air yield an actual fait. 



Thefe things being premifed, we are to confider 

 the gold in the pyrites in a threefold view : 



(1.) As it is feen in the common way of proof, 

 by means of lead and aqua-fortis. 



(2.) As 



