l%\ Of the Vitriol 



of iron and copper, feems, though I cannot pofi- 

 tively fay it does, to partake of fomething alumi- 

 nous. We have few inftances in the grooves of a 

 pure, fimple, either martial or venereal, vitriol \ 

 and when we would have it pure, the mod careful 

 methods of refining, evaporation, and cryftallifa- 

 tion, muft be employed ; or, which is the furefl 

 method, the vitriol is to be prepared originally 

 from its metal, either iron or copper : and that, 

 both from the nature of the pyrites •, not only in 

 themfelves, or as vitriol matrices m their mixtion 

 (as being feldom pure irony, though the iron ge- 

 nerally predominates, nay, is often the only metal 

 in them, and a copper-pyrites, even that fort, on ac- 

 count of its rich copper-yield, called a copper-ore, 

 is never without iron) but alfo from the nature of 

 its encompafling rock and Hone; in particular, 

 the black, fatty, and fhivery fort, as matrices of 

 the pyrites, wherein there is generally, at the fame 

 time, alum generated : whence alfo the famous 

 Heflian iron-earth is not always naturally pure in 

 iron-vitriol, but often yields adtual alum, which 

 muft carefully be parted from the vitriol. 



(2.) Though this firft darling of vitriols, with 

 refped to their effence, might feem fufficient, yet 

 it may not be amifs to take fome notice of their co- 

 lours, feeing thefe firft ftrike the eye : thefe, exclu- 

 fxve of the white vitriol, may be reduced to a green, 

 or a blue, the green martial, the blue venereal ; 

 the former is very pale, like a pale emerald, com- 

 monly called a grafs, or fea- green, and ought not 

 to be confounded with verdegreafe, the colour of 

 which is a much higher green, fomewhat inclining 

 to a bluifh caft, cfpecially when prepared by art 

 From copper and a vegetable acid. The blue re- 

 fembles a beautiful fapphire and a laful-ftcne, as 

 - ™ this 



