CATALOGUE OF PHILOSOPHICAL APPARATUS, &c. 37 



Drawer 91. (i) Marl with marine shells, near Rome. 

 (2) Trachyte of Tolfa near Civita Vecchia. 



Showing the various stages of its decomposition, and the production 

 thereby of alumstone, from which the famous Roman alum was 

 manufactured. 



See Supplement to " Volcanos," p. 814. 



Drawers 92, 93, 94. Volcanic Tuff of Rocca Monfina, an extinct volcano 

 between Rome and Naples, together with the Trachyte which 

 forms its summit. 



The tuff from the side of the mountain contains various blocks 



imbedded and large crystals of leucite. 

 Its composition is 



3KO, 2Si 3 + 3 (Al a 3 , 2Si 3 ). 

 It is very rare at Vesuvius. 

 See " Volcanos" chap. x. and a memoir of mine in the Transactions of the Ashmolean Society. 



Drawer 95. 



Drawer 96. Volcanic Tuff of various kinds including the rock called Piperno, 



from the neighbourhood of Naples. 



See notice of a Paper read by me to the British Association, in the Volume of Reports for 

 1859, p, 102. 



Drawer 97. Do. chiefly from Pompeii, Herculaneum, Nola, with Obsidian 



and Pumice imbedded. 



N. B. It may be remarked, that Obsidian and Pumice are not ejected by the volcano at the 

 present time. 



Drawer 98. Volcanic Tuff from the Fossa grande Vesuvius, St. Rocca, and 

 other places near Naples. 



Containing shells similar to those of the Mediterranean at present. 

 This is one argument employed in favour of the elevation of the 

 mountain from the bed of the Mediterranean at some former 

 epoch. 



Drawer 99. Volcanic Tuff called Puzzolana from the neighbourhood of 

 Naples. 



Drawer i oo. Tuff and other rocks from Lake Agnano, Monte Nuovo, Astroni, 

 &c. near Naples. 



Drawer 101. Specimens from the Solfatara. 



Shewing the trachytic current of Mount Olifrano, and the trachyte of 



