from & P y r i T e s, 313 



in colour, tafte, or habitude in the fire. And all we 

 learn from the accounts from the Rammelfberg is, 

 that the ores there are alfo fyrity and mock-leady. 



In the PretzfchendorfT fort, it is certain, that be- 

 fides the pyrites, there is alio mock-lead, which 

 holds fome iron-earth, and a little footy fly-pow- 

 der, or arfenic, confequently no other contents than 

 what are in pyrites, and therefore the bufinefs fhould 

 feem to turn on the unmetallic earth, which confti- 

 tutes the greateft part of mock-lead, befides what 

 the external rock may contribute ; which though 

 alio to be met with in other pyrites, yielding no 

 white vitriol, yet we are to remember, that new 

 productions, as vitriols are, depend not fo much 

 on the great variery of matters to make up their 

 mixtion, as on the different proportions of a few, 

 the places of generation, &c. 



From the former prejudice generally arifes great 

 difficulties in acquiring a competent knowledge of 

 nature, in imagining, firft, mixts to have taken 

 their rife from fuch matters as they are found to con- 

 fift of; the abfurdity of which appears from the hi- 

 ftory of alum, which confiits indeed of a calcarious, 

 or if you had rather, a chalky earth, and yet nei- 

 ther nature nor art can produce it from thence : a- 

 gain, in being accuftomed, in the operations of na- 

 ture, to the terms, extraction, feparatien, combina- 

 tion, &c. 



As to the mixtion or nature of the white vitriol, 

 h far as my little obfervation reaches, it may be 

 concluded, its ground-earth is, firft, aluminous, 

 then, coppery •, the copperinefs not only appearing 

 in the common white vitriol, as worked from the 

 Rammtifberg ores, by plunging an iron into ir, 



buc 



