84 
CONTRIBUTIONS TO MINERALOGY. 
[BULL. 263 
IJoth of these residues were perfectly white and entirely crystalline. 
Thallium chabazite is easily decomposed with nitric acid, yielding 
sandy silica. 
Derivative D gives the following- ratios: 
lsTL.0, 2CaO, lNa 2 0, 22A1 2 3 , 100SiO 2 , 15H 3 0; 
or, combining monoxide bases, 
R" 21 Al, 4 Si 100 O 287 .15H 2 O. 
The ratio of the two acid radicles is 
16SiO,:28Si 3 8 ; 
and, inserting these in the formula, we have 
R" 21 Al 44 (Si0 4 ) 16 (Si 3 8 ) 28 .15H 8 0; 
or, condensed, 
R" 21 Al 44 X^.15H 2 0=l-2-2+aq. 
A rough experiment was made by heating silver chabazite in a scale 
tube with a 10 per cent solution of lead nitrate. The residue aftii 
washing and drying contained 5.50 per cent Ag 3 and 20.24 per cert 
PbO. 
STILBITE. 
The specimen of stilbite used came from Wassons Bluff, Nova Scotiifl 
The action of silver nitrate upon this mineral was not investigated. I 
One thallium derivative was made by heating the stilbite in a seal* | 
tube with four times its weight of thallous nitrate sixty-five hours 1 
230°-280° C. The residue was perfectly white, entirely crystallimJ 
and biaxial, and it gave sand}^ silica with nitric acid. The analyst! 
follows: 
SiO, 
A1 2 3 - 
Fe 2 3 
T1,0 . 
CaO.. 
Na 2 . 
H 2 0- 
H 2 0+ 
Stilbite. 
55.41 
16. 85 
.18 
7.78 
1.23 
3.60 
15.41 
100.16 
Residue. 
36. 75 
11.74 
42.94 
.68 
.15 
5.48 
2.29 
100. 03 
Mole, 
rati 
1 
