INDEX. 335 



Hypothefis on the volcanic origin of china-clay and bo- 

 lus, 54. 



Account of the mountains at Montleri, 255. 

 Hypothefis on the origin of the Travertino, 255. 

 Arcluim (Pictro) at Padua, 14. 

 Argillaceous Jlones. 



Some produced from lava changed and affected by fulphu- 



reous acids, 166. 

 See Barddloni, 

 Horn-flats^ 

 Mica, 



Serpentine-Jlonc t 

 Slate. 



Arlcchlno antico, or di Seme Santo marble, 215. 

 Arfcnic, red, native, Vefuvian, ig. 

 cryftallized in the Solfatara, 169. 



in Serpentine-ftone and its fiffures, 85, 90, 277. 

 See 



j4Jbes (volcanic). 



Stratified, 127, 28. 

 Varieties about Vefuvius, 158, 159. 

 Mixed with fherl polygons, 162. 

 Effervefce with acids, 162, 63. 

 AJbes (volcanic). 



See F~olcanlc productions* 

 Piperino. 

 Pozzulana, 

 Tufo. 



tj never found on Vefuvius, i65. 



