THE ACTION OF SILVER NITRATE AND TH ALLOCS NITRATE 
UPON CERTAIN NATURAL SILICATES. 
By George Steiger. 
The following investigation is practically a continuation of the 
Bxperiments which were described by Clarke and Steiger in a recent 
bulletin of the United States Geological Survey/' although the new 
work is along somewhat different lines. 
In the former research the alkalies and alkaline earth metals of cer- 
tain silicates were replaced by ammonium, when the minerals were 
heated in sealed tubes with ammonium chloride. In the present work, 
silver nitrate and thallous nitrate have been substituted for ammonium 
chloride, the temperature employed being somewhat above their fusing 
points. As was anticipated, the alkalies and alkaline earth metals 
were replaced by the heavy metal, thus giving additional data rela- 
tive to the constitution of the minerals. 
The experiments were carried out as follows: The very finely ground 
material was mixed thoroughly with various amounts of nitrate by 
rinding in an agate mortar, the mixture was placed in a tube of Jena 
glass, and the tube was sealed. These tubes were then heated in a 
bomb furnace for the specified time and temperature, then opened 
tnd the contents leached with boiling water till the filtrate gave no 
est for nitrates. The residue was then dried and analyzed. 
In a recent paper/' the writer gave the results of some preliminary 
vork on analcite and chabazite. 
Heumann' prepared a silver ultramarine by boiling the native min- 
eral with a solution of silver nitrate, and A. H. Church' 7 made a silver 
>hillipsite by allowing a solution of silver nitrate to act on the natural 
uineral at ordinary temperatures for almost three years. 
For the optical notes in the present paper, the writer is indebted to 
lessrs. W. T. Schaller and J. S. Diller. 
The crystals in all cases were too small to permit a determination of 
leir forms. A few optical observations were made, and with the 
xception of the isotropic compounds, it can be said that all were 
ntirely crystalline. 
" Bull., C. S. Geol. Survey No. 207. cLieb. Ann,, vol. 199 l 1879), p. 253. 
'-Am. Jour. Sci., ser. 4, vol. l |. July, 1902, p. 31. *'.Min. Mag., 1899, vol. 12. p. «t. 
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