88 CONTRIBUTIONS TO MINERALOGY. [bull. 
These proportions agree fairly well with the formula 
R' 2 Al 2 Si 3 O 10 , -f-aq. 
The reaction in this case was incomplete, only a little over one-h 
the calcium and none of the sodium being- replaced, but the experiiiK 
shows that the desired molecule was partially formed. 
MESOLITE. 
The mesolite studied was a tine specimen of crystalline matei 
from Ostero, in the Faroe Islands. 
One thallium derivative was prepared by heating the mesolite h 
sealed tube with four times its weight of dry thallous nitrate 
eighty hours at 240°-280° C. 
Its analysis and that of the mesolite follow: 
Si0 2 _. 
A1A- 
TLO .. 
CaO... 
Na 2 . 
H,0- 
H 2 0+ 
Mesolite. 
45. 97 
25. 98 
Residue. 
In the leach water: 
A1A 
CaO 
Na 2 
9.69 
4.79 
1.34 
12.04 
99.81 
29.11 
16.94 
44. 75 
2. 90 
.26 
3.32 
3.06 
100. 34 
None. 
5.50 
4.42 
Moleci 
ratio 
1' 
The leached residue was perfectly white and entirely crystal 
with parallel extinction. It gave a perfectly clear solution with ; 
which gelatinized on slight evaporation. 
The molecular ratios are as follows: 
22Tl 2 O,llCaO,lNa 2 O,34Al 2 O ;5 a00SiO 2 ,35H 2 O. 
Combining monoxide bases, we have 
-^ c8Al 68 oi 100 0. {3C .f3oH 2 (J, 
agreeing almost perfectly with the formula 
R' 2 Al 2 Si 3 O 10 .H 2 (X 
