Analysh of some Scottish Zeolites. 281 



This calculation presents a very close agreement with the 

 experimental results in all the constituents, with the excep- 

 tion of the soda, which differs to some extent, but still so 

 little as to render it obvious that the above must be its for- 

 mula. 



I have called this mineral Pectolite, because its chemical 

 composition and its external character, so far as they can be 

 determined by the description given in books, agree very 

 closely with those of the mineral described by Von Kobell 

 under that name ; but not having seen a specimen of the 

 true mineral from Monte Baldo, I cannot pronounce upon it 

 with absolute certainty. Analyses of the true pectolite, and 

 of another mineral occurring at Royal Island, in Lake Su- 

 perior, in North America, have been already published, and 

 their results are as follow : — 



Monte Baldo. 



Royal Island. 



Von Kobell. 



A. 



B. 



Silicic acid, . 51 '30 



53-45 



5566 



Lime, . . . 33-77 



31-21 



32-86 



Alumina, . . 090 



494 



1-45 



Soda, ... 8-26 



7-37 



7'31 



Potash, . . 1-57 







Water, . . 389 



2-72 



2-72 









99-69 



99-69 



100-00 



These analyses are somewhat conflicting ; but the first, by 

 Von Kobell, approximates very nearly to my analysis of 

 the Skye mineral. From the former Berzelius has deduced 

 the somewhat complicated formula : — 



3(NaOSi0 3 ) + 4(3Ca0 2Si0 3 ) + 3HO 



The calculation of which gives — 



Silicic acid, 11 atoms = 508-442 = 52-603 



Lime, 12 ... = 337*584 = 34-927 



Soda, 3 ... = 93-534 = 9667 



Water, 3 ... =27* = 2793 



966-560 

 which certainly does not agree by any means so well 



