123 



in its external characters, but differs in appearance from that mi- 

 neral, in possessing a much higher lustre. Its quantitative analysis 

 gave the following results. 



99-805 



agreeing with the formula, 



Na 0, Si O3 + (4 Ca 0, 3 Si O3) + 2 HO, 



the calculation being, 



Silicic acid, 4 atoms, 181-2 — 52-6 



Lime, 4 ... 112-0 - 32-4 



Soda, 1 ... 31-3 - 9-1 



Water, 2 ... 18- 



342-5 100 



which approximates much more closely to the experimental results, 

 than the complicated formula proposed by Bcrzelius, 



3 (Na O, Si O3) -r4 (3 Ca O, 2 Si O3) + 3 HO. 



The occurrence of this mineral in Scotland has not been hitherto 

 noticed. 



Natrolite. — A specimen received from Mr Rose of this city, and 

 found in a railway tunnel at Bishopstown in Eenfrewshire, was 

 found to consist of 



Silicic acid, . . 47*626 



Alumina, . . . 27-170 



Soda, . . . 15-124 



Water, . . . 9-780 



99-700 



Corresponding with the well-known formula of Natrolite, 



Na O, Si O3 + Alj O3, Si O3 + 2 HO. 



Laumonite. — Found at Storr in Skye, in a vein traversing trap, 



k2 



