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ford fparks with ft eel, it has been proved 

 that there are feveral Vv^hich have tlils qua- 

 lity. I pofTefs feverrJ fpecimens of n^iar- 

 bies, that I colle<Sted fome years fmce in 

 the quarries of Carrara, which when ftruck 

 againft fteel afford no inconfiderable quan- 

 tity of fparks. The fame may be faid of 

 the effervefcence with acids, there being fe- 

 veral kinds of thefe carbonates in which 

 acids caufe no motion, though they fuffi- 

 ciently diffolve them. 



To obtain proofs lefs equivocal, whether 

 this tranfmutation really took place, I re- 

 folved to have recourfe to chemical analyfis, 

 making my experiments on fragments of 

 the fame piece, fome entirely white, othei'S 

 of a very light red, others ftill reddei% and 

 others of a deep red. The refults were as 

 follow : 



In the fragments of the iirft kind, I 



found the quantity of lime very great, and 



that of filex very fmall ; negleding, at than 



time, the carbonic acid gas, and the fmall 



R 4 portion 



