SiOs .. 

 AUO3 . 

 Fe^O, 

 FeO .. 

 MgO . . 

 CaO. . 

 NagO . 

 KjO.. 

 H„0 .. 

 Tibo.. 



Sp. Gr. 



ITALIAN PETROLOGICAL SKETCHES 49 



TABLE I. 



55.87 



21.82 



2.34 



1. 10 



0.48 



3-07 



4.81 



10.49 



0.34 



100.32 

 2.551 



1. Toscanite, Monte Calvario, Bracciano, A. Rohrig anal. 



2. Toscanite, Monte Cucco, Cerveteii, H. S. Washington anal. 



3. Toscanite, Castle Hill, Tolfa, H. S. Washington anal. 



4. Toscanite, Tolfa, vom Rath, op. cit., 596. 



5. Leucitite, Crocicchie, Bracciano, H. S. Washington anal. 



6. Leucite-tephrite, Bracciano, H. S. Washington anal. 



7. Leucite-phonolite, Lake Bracciano, H. S. Washington anal. 



Henry S. Washington. 



' By difference, through loss of Mg precipitate. 



