Salts. 189 



SPECIES VIII. 



Vitriol of Iron. 



It is of a greenifh colour when perfectly 

 and recently cryftalized, but efflorefces by 

 expofure to the air, and becomes yellowifh : 

 it requires 6 times its weight of water to dif- 

 folve it in the temperature of 60 ; its acid is 

 known by this, that the folution of this fait 

 mixes without turbidity with the folutions of 

 other ialts that contain the vitriolic acid, as 

 Epforn, felenite, tartar vitriolate, &c. but 

 renders the folutions of nitrous or marine 

 felenite turbid ; and its bafis, by the black 

 colour which the folution of galls or vegeta- 

 ble aftringents immediately produce in its 

 folution. 



100 Parts of it recently cryftalized contain 

 20 of real acid, 25 of iron and 55 of water. 



It is frequently found native, either in 

 coal mines, or in the cavities of pyritaceous 

 mines, or adhering to the fcaffolds in a ftalac- 

 titical form. Alfo in fmall round ftones called 

 Ink ftones, of a white, red, grey, yellow or 

 black colour, which are almoft intirely folu- 

 ble in water, and contain a portion of copper 

 and zinc. 2 Schlutter, 620. 2 Jars, 26$. 

 Alfo fometimes in ihiftus. But the greatdl 



part 



