SES tn Se 
pe ee ble eke | tee is See eae 
. pig SS Gy Si me 
A. W. Wright—Gases in Smoky Quartz. 215 
presence of a hydrocarbon of the nature of bitumen, which is 
driven off by heat, and the partial decomposition of which, at 
the high temperature reached, accounts for the heavy hydro- 
carbon found in the residual gas, or condensed upon the walls 
of the cooled tubes. These facts, moreover, are entirely in 
harmony with and confirm the conclusion of Forster* from 
an examination of the remarkable smoky quartz from the 
canton of Uri, that the color of the latter is due to the presence 
of some volatizable hydrocarbon, though they do not directly 
connect the ammonia with the latter, as his observations ap- 
pear to do. 
After the operation just described had been concluded, some 
pure distilled water was introduced into the bolt-head, and 
argentic nitrate it gave a considerable precipitate of argentic 
chloride, while when examined spectroscopically it afforded 
satisfactory evidence of the presence of sodium, but of no 
other metal. The water previously examined was found to be 
free from both chlorine and sodium. The bolt-head had been 
scrupulously cleansed before use, and great care was taken in 
this, as in all the experiments, to prevent contact of the quartz 
with things that might communicate to it any impurity. This 
result would indicate that the cubical crystals observed by 
Mr. Hawes in some of the cavities were chloride of sodium. 
Search was also made for chlorine or cblorine compounds in 
converted into vapor. Taking the amount of water. per cubic 
centimeter at 1:62 cubic millimeters as found above, this mul- 
for one 
aa retail derived from No. 2 above, where the water determi- 
nD 
oa of measurement being about 20° C., we have for the 
“ume at 100°, neglecting the correction for the barometric 
te which was not greatly different from 760 mm., 1-23 
eTESSu 
pew centimeters. Reduced to parts in 100 these volumes 
* Pogg. Ann., exliii, 173, 1871. 
