80 
CONTRIBUTIONS TO MINERALOGY. 
[BULL. 2(32. 
Si0 2 . 
AljOj 
Ag 2 free 
CaO 
Na 2 .... 
H 2 0-... 
H,0+--- 
In leach water: 
CaO 
NaX> .... 
Natural 
thomsonite. 
41.13 
29.58 
11. 25 
5.31 
1.01 
12.12 
100. 40 
Silver 
thoinsonite. 
33.80 
23. 21 
23. 50 
2.56 
7.28 
.71 
.45 
s. 11 
99. 6| 
2. 68 
5. 04 
The color of this residue was dark, showing that some silver oxide 
had been formed, so contaminating the salt. A determination of thl 
free silver oxide was made by the following method, and it appears im 
the analysis as ' l Ag 3 free." 
A portion of the silver thomsonite was weighed out in a platinumi 
boat and placed in a glass tube, which was connected with a weighed* 
calcium chloride tube; .low red heat was then applied and at the samcM 
time a current of dry air was passed over it. At this temperature! 
silver oxide is decomposed, liberating the entire amount of oxygen i 
The loss of weight in the boat was water plus oxygen, the gain in th< 
tube was water alone; the difference represented the oxygen of the 
free silver oxide. 
The new compound dissolves easily in dilute nitric acid to a clea 
solution, which forms a perfect jelly on evaporation. Under th< 
microscope the material proved to be entirely crystalline, showing 
parallel extinction. 
Deducting free silver oxide, and also the water lost below 100°, am j 
reducing to 100 per cent, the analysis gives the results tabulate] 
below: 
sio, . 
A1 2 3 
A&O 
CaO . 
Na 2 
H 2 0. 
Silver thorn 
sonite re- 
duced. 
34.99 
24.02 
24.32 
7.54 
0.74 
8.39 
100. 00 
Moleculaf 
ratios. 
100. 
40. 
18. 
23. 
2 J 
