354 M. Rose on Analcime, [May, 



decomposed by carbonate of ammonia ; the precipitate, except 

 a slight trace of silica and oxide of iron, was dissolved by 

 potash. The solution, after the silica and alumina were sepa- 

 rated, was evaporated to dryness, and the residuum was heated 

 until all the muriate of ammonia was volatilized. The residuum 

 gave cubic crystals of common salt free from potash. The 

 results of the analysis were : 



Silica , 55-12 



Alumina 22-99 



Soda 13-53 



Water. ...•••• 8 * 27 



99-91 



I found upon trial that the white transparent analcime which 

 is found in the lava of Catana, in Sicily, was of similar composi- 

 tion ; but the quantity I possessed was too small to make a com- 

 fdete analysis, and the fragments were mixed with carbonate of 

 ime. 



I analyzed another analcime from Fassa, different from that 

 which I have just mentioned, and I found that its composition 

 agreed perfectly with that of the preceding ; the results of the 

 analysis were 



Silica 56-47 



Alumina 21-98 



Soda . < . . ,\ 13-78 



Water 8-8i 



101-04 



This analcime was of a flesh-red colour, on which account the 

 name of sarcolite has been given to the analcime of Montecchio 

 Maggiore, near Vicenza, and in which M. Vauquelin found 



Silica , , 50-0 



Alumina 20-Q 



Water 21*0 



Soda and potash 4*5 



Lime 4-5 



Iron Trace 



100-0 



I cannot explain the great difference between M. Vauquelin's 

 analysis and mine ; I think I have, however, some reason for 

 supposing that the sarcolite which he analyzed was not quite 

 pure ; for sometimes the large crystals of analcime which are 

 found in the valley of Fassa, are so filled with perfectly well 

 defined crystals of apophyllite, that they form almost half the 



