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to which we may add a third, which is the 

 lofs of the iron, Ukewile an aid to fufion, ' 



Thefe fulphates, which for the inofl: part 

 accompany lav.as, prefent a pleafmg fpec-» 

 tacle to the naturalift. Their colours are 

 infinitely varied. Thofe which are moft 

 prominent to the eye, are the rofe colour, 

 violet, and orange, and they are the more 

 confpicuous becaufe they are generally 

 placed on a white ground. 



I have obferved three kinds of fulphate 

 of lime, independent of feveral varieties 

 which I omit. The firft is compofed of 

 thin plates, parallel to each other, clofely 

 united, brilliant, compad, and opake. They 

 form ftrata or beds of diiferent thicknefs, 

 fometimes more than a foot, and thefe ftrata 

 are eafily detached from the lavas to which 

 they adhere. 



The fecond fpecies is filamentous, having 



either parallel or ftellated filaments, in which 



Jatter cafe tl,e filaments form a kind of py-? 



ramids, which have their apices in one 



6 commo?! 



