from ^Pyrites. 3 \q 



neous evaporation, without applying any fire, and 

 thus let it Hand for fome months, and there will 

 fomething feparate in that time, which proves not 

 cryftalline, but crumbly, like hemp-feeds and fmall 

 peafe, and what remains after, proves ftill thick 

 and oleaginous, as before. Now nothing further 

 happens, but that when the lafl is not removed 

 with the fame care, but the whole left long toge- 

 ther to dry away in the mild warmth of a ftove, 

 this oleaginous mafs, when become of the thick- 

 nefs of butter, heaves and rifes like a dough, in 

 its ftate of fermentation. 



As to what M. Geoffroy * has obferved in this 

 cafe, though he divides vitriol with more accuracy 

 than M. Lemery, into blue, green, and white* 

 yet he appears not to have had fo juft a notion of 

 the white fort, which he calls cmtpercfe blanche f , 

 as he pretends it to be mixed either with fome ca- 

 lamy (which it may, in regard to the earth it holds 

 for the generation of alum, and poflibly alfo for 

 the bafis of the white vitriol) or to confift of an 

 irony earth, and fome lead or tin, a prejudice he 

 was probably led into from the white colour of the 

 vitriol. 



Now the oleaginous fmeary matter remaining 

 after the (hooting of the vitriol, and which he calls 

 the mother-water, he procured not only from frefh 

 vitriol, but alfo from the fort he dried to whitenefs, 

 and likewife from what he had treated in the fire, 

 to yellownefs, for obtaining the volatile fpirit of 

 vitriol. He then obferves, that from frelh vitriol, 

 upon the firfl re-folution and cryftallifation, a grey 

 muddy earth had fettled to the bottom of the glafs ♦, 



a thing 



* Hift. de TAcad. YAn. 1707. p. 237. 



•j- lb. l'An. 1713, p. 48. & Mem. p. 225. 



