STAGER.] ACTION OF SILVER NITRATE, ETC., ON SILICATES. 
89 
These three minerals and their derivatives give the following com- 
parison, when all the monad and dyad bases are united under R": 
Native natrolite R // 36 A1 66 Si 100 O 335 . 72 H 2 
Silver natrolite R // 33 A1 62 Si 100 O 326 . 70 1 1 ,( ) 
Thalliuin natrolite R",,, Al 70 Si 100 O 339 . 9 1 1 2 
Native scolecite W^Al^ Si 100 O 333 . 99 H 2 
Silver scolecite R // 31 A1 68 Si 100 O 33S . 71 U.,() 
Native mesolite R // 33 A1 66 Si 100 O 332 . 87 H 2 
Thallium mesolite R // 34 A1 68 Si 100 O 33(; . 35 H 2 
Since, as others have shown, the water in these three minerals plays 
no part in the chemical molecule, it has been placed as a separate con- 
stituent in the formulae. 
The ratios found are not so sharp as could be desired, nor have the 
reactions been complete, but they indicate that the three minerals are 
all derived from the trisilicic acid H 8 Si 3 O 10 . 
Deducting- from each of the above formula? the water contained in 
the undeeomposed mineral, which latter is represented by the amount 
of alkali retained by the derivative, we have the water contents: 
Silver natrolite 70 H 2 less 18 H 2 equals 52 H 2 
Thallium natrolite 9 H 2 less 8 H 2 equals 1 H 2 
Silver scolecite 71 H 2 less 50 H 2 equals 21 1 1,( ) 
Thallium mesolite 35 H 2 less 29 1 1 2 equals 6 H 2 < ) 
We have here, as was the case with the thomsonite, chabazite, and 
stilbite derivatives, silver compounds strongly hydrated, while the 
thallium salts are practically anhydrous. 
PECTOLITE. 
The pectolite came from Bergen Hill, N. J. It contained a small 
amount of calcium carbonate as an impurity. 
A single silver derivative was made by heating the pectolite in a 
sealed tube with four times its weight of dry silver nitrate, for twenty- 
two hours at 240°-280° C. The residue was dried on the water bath. 
On analysis the following results, stated below, were obtained. 
Pectolite. 
Si0 2 .. 
A1A- 
Ag 2 0. 
CaO.. 
MnO. 
Na 2 0. 
H 2 
H 8 0+ 
co 2 ._ 
53. 34 
.33 
33.23 
.45 
9. 11 
.27 
2.70 
.67 
100.10 
Residue. 
39. 05 
.38 
32.57 
18. 13 
5. 99 
4. l: 
100.24 
Molecular 
ratios. 
100. 
21.5 
49. 8 
14.9 
35.2 
