THE 
EDINBURGH 
PHILOSOPHICAL JOURNAL. 
Art. I. — On the Chemical Composition of some Minerals of 
the Zeolite Family ; with an Account of two new Substances^ 
Mesole and Mesoline. In a Letter to Dr Brewster from 
M. Berzelius. 
Sir, 
In compliance with your request, I have analysed the Apo- 
phyllite of Faro, whose action upon polarised light presents 
such remarkable peculiarities^ that you have considered it as a 
new mineral species, and given it the name of Tesselite. 
The investigations in which you are occupied, respecting the 
action of crystallised substances upon light, are of such high 
importance, that I feel it my duty to do every thing in my 
power to furnish you with the analytical data which you re- 
quire ; and though the result which I have obtained in the ana- 
lysis of the Tesselite^ does not appear to confirm ;^our conjec- 
ture respecting the difference between its composition and that 
of the other apophyllites I shall communicate to you the ex- 
periments which I have made upon this mineral. 
The specimens of Tesselite with which Sic George Mackenzie 
had the goodness to supply me for analysis, though very large 
* See the follotying Article. — E d. 
VOL. vri. NO. 13. JULY 182^. 
A 
