52 Mr Connetx’s Description and Analysis of 
From table-spar, the mineral obviously differs in containing 
water as an essential constituent, and in the relative proportions 
of silica and lime, table-spar being a bisilicate of lime. From 
those zeolites which do not contain alumina as a necessary in- 
gredient, such as apophyllite, and Dr Tuomson’s wollastonite, it 
differs, in respect that the quantity of alkali is too small to be 
viewed as an essential constituent, as well as in the relative pro- 
portions of silica and base. 
As soon as I had completed the analysis, I sent an account 
of the result to Sir Davin Brewster, who was so kind as to 
examine a few of the optical properties, and to give me the fol- 
lowing notice of his observations : 
* My Dear Srp, 
“ T ought to have thanked you sooner for your letter of the 
5th December. There can be no doubt that the mineral is a 
new one, and I have made various ineffectual attempts to obtain 
crystals from the surface of the large specimen which I have of 
it, and which I received from Count Vareas Bepemar. The 
crystallized faces are perfectly distinct, but they lie so near the 
general surface, that it is impossible to detach any fragment 
without pounding it. 
« T have, however, ground and polished a piece of the tough 
mass, and have ascertained that it possesses double refraction. 
It is also opalescent, reflecting a bluish light, and consequently 
transmitting a yellowish one. I have also found that its powder 
possesses no pyro-electricity. I cannot help thinking, that, by a 
careful examination of different specimens, small crystals will be 
found in some of the superficial cavities. I am, My Dear Sir, 
ever faithfully yours, 
« D. Brewster.” 
“ Belleville, Dec. 26. 1833.” 
