{ 26l ) 



canic pitch-ftone lavas, whatever may be 

 their colour, as foon as they are expofed to 

 our common fire, become red. 



Thefe pitch-ftone lavas, which are found 

 In other parts of the Eugahean mountains 

 befides thofe already mentioned, have in- 

 duced Father Terzi, a Benedld:ine, to fup- 

 pofe that they were no other than real 

 glafs, an opinion which he publifhed a few 

 years fmce in fome letters on the Euganean 

 produdis. He informs us that he difcovered 

 large veins of them in the Mont^ del Muflato, 

 and at Brecalon, as well as in other places. 

 The novelty of the difcovery greatly ex- 

 cited the furprife of many Paduan natural- 

 ifts, and efpecially of the Abbe Fortis, who 

 having frequently made excurfions to thefe 

 mountains to examine their products, could 

 never meet with this extraordinary glafs. 

 To afcertain the truth, he, with fome other 

 perfons well acquainted with tjiis branch of 

 natural fcience, repaired to the mountains, 

 and foon difcovered the error which had 

 been committed by the good Father mif- 

 S 3 taking 



