itEiQER.] ACTION OF SILVER NITRATE, ETC., ON SILICATES. 85 
Omitting water lost below LOO , we have the following ratios: 
L6 Tl,(). 2 CaO, 1 Na 2 0, 19 A1 2 3 , LOO Si0 2 , 20 11,(); 
and, combining monoxide bases, 
R" 1 ,Al„Si 100 O,„, 20H 2 O; 
which gives a ratio between the two acid radicles of 
7 SiO,:31 Si 3 8 . 
Inserting these in the formula, it becomes 
R" 19 Al S8 (SiO 4 ) 7 (SiA) 31 .20H 2 O, 
which condenses to 
R" 19 A1 38 X 38 .20 H,0. 
Reducing the analysis of stilbite in the same wa}% we get 
R" 17 Al 36 (Si0 4 ) 4 (Si 3 8 ) sa .93 H,0=l-2-2, 5 ILO. 
From the last three minerals we get the following formulae: 
Native thomsonite R // 42 Al 85 (SiO l ) 7(; (SiA)8- 98H 20=l-2-2,2^H,0. 
Silver thomsonite R%Al 80 (-SiO 4 ) 73 (Si 3 ( > 8 ) 9 .80H 2 O=l— 2— 2,2H 2 0. 
Native chabazite R // 20 Al 40 (SiO 4 ) 10 (Si 3 O 8 )3 .109H 2 O=l— 2— 2,5J H 2 0. 
Silver chabazite R" 20 Al 40 (Si< ) 4 ) 10 (Si 3 O 8 ) 30 .42H 2 O==l- -2 -2,2H 2 0. 
Thallium chabazite R'^AhJsK > 4 ) 16 (Si 3 < ) 8 ) 28 . 15H 2 < >=1 2 2,Aq. 
Native stilbite .._„R%Al 36 (Si0 4 ) 4 (Si 3 < > 8 ) M .93H a O=l— 2— 2,5H 2 ( ). 
Thallium stilbite R // 19 Al 38 (SiO 4 ) 7 (Si 3 O 8 ) 31 .20H 2 O=l-2-2, Aq. 
The similarity of the foregoing formula 1 is plainly evident. Leav- 
ing water out of consideration, and except in the single case of silver 
thomsonite, the ratios agree closely with the ratios of 1-2-2 for the 
monoxide base, aluminum, and silicic acid. It will be seen that with 
jthe two silver derivatives, compounds retaining two molecules of 
water were formed, although in the case of thomsonite a mineral 
hydrated with 2i molecules of water was taken, while the chabazite 
contained 5^. 
NATROLITE. 
The natrolite which was studied came from Bergen Hill, N. J. 
Two silver derivatives were made, as follows: 
A. Natrolite was heated in a sealed tube with a 10 per cent solution 
f silver nitrate, eighteen hours at L20° C. 
B. Natrolite was heated in a scaled tube with four times its weight 
f dry silver nitrate, twenty-two hours at 250 -290 C. 
