the Pyrites, GV. 371 



is lighter than yellowifh, or iron pyrites, though 

 the latter confifts only of iron and fulphur, but the 

 former of copper and arfenic (at leaft more than 

 the latter) which are heavier than iron and ful- 

 phur ; and from this we muft needs conclude cop- 

 per-pyrites to hold more unmetajlic, confequently 

 more light earth. But, to fay the truth, the hy- 

 droflatical balance is far from being that abfolute 

 means of a-ttaining to the entire and full knowledge 

 of bodies, which fome philofophers, who might be 

 too nice to fmut their hands with chemical pro- 

 cefTes, would have us to take it for, whatever 

 fhort auxiliary means it may otherwife be : nay, 

 nor this balance, nor the fire alone, nor air, nor 

 depart-waters alone, nay, often, not all of them 

 together are fufrkient to difclofe to us the fecrets of 

 nature. 



III. Mifcellaneous Obfervations and Experiments on the 

 Pyrites. 



I. Native filver is moll commonly found either in. 

 pure quartz, or near and on cobald, and confequent- 

 ly on an arfenic-ore ; though mijfpickel, or arfenic -py- 

 rites y equally with cobald, be arfenical, yet we 

 have hitherto had no inftance of native fiiver there- 

 on, which muft be owing to its iron, or other 

 earth, hindering the production thereof. 



II. Native gold is, in like manner, commonly 

 found in pure quartz, never on cobald; whereas, 

 on the contrary, 'tis to be found on mifjpickel. 



III. On yellowifh and yellow pyrites we find nor 

 gold nor filver, at leaft, not as growing from fach 

 pyrites. 



IV. I have been lately fhewn a fample of kneifs 

 with yellov, ifli pyrites , and capillary filver lying 

 thereon, as if the filver grew from the Pyrites y but 



B b 2 firft 



