502 RK. T. CHAMBERLIN 
which was capable of pulverizing a rock specimen in a complete 
vacuum. Any gas liberated could then be pumped off and analyzed. 
Two specimens of basalt, one from the Faroé Islands and the other 
from Hawai, gave little or no gas. Vein quartz from Iron County, 
Utah, gave no trace of gas. Being desirous of finding some specimen 
which would yield gas when crushed in this manner, I procured some 
crystals of cavernous quartz from Porretta, Italy, in which several 
of the cavities exceeded a millimeter in diameter. These, when 
crushed, yielded carbon dioxide amounting to only .03 of the volume 
of the quartz. An analysis showed also a little methane and some 
nitrogen, but the amount of gas available was too small for the determi- 
nation to be of any value.. The result of this last test agrees with the 
microscopic studies of the early investigators. Carbon dioxide exists 
in the cavities of quartz, but its volume, compared with the volume 
of inclosing mineral, is small. 
GASES DUE TO CHEMICAL REACTIONS 
We may note very briefly the possible sources of gas from high- 
temperature reactions between the non-gaseous constituents of the 
rocks. 
Hydrogen may be produced at temperatures above 500° through 
the decomposition of steam by a ferrous compound. 
Carbon dioxide is liberated when an ordinary carbonate is heated 
sufficiently, and hence if the rock specimen be slightly carbonated, 
gas will be derived from this source and will embarrass the determina- — 
tion of the free gas. 
Carbon monoxide is formed from carbon dioxide when that gas 
is heated in the presence of iron in the ferrous condition, and also 
to a lesser degree when heated with free hydrogen. 
Possible sources for methane are carbides, the decomposition of 
organic matter, and the reaction between carbon monoxide and free 
hydrogen which gives marsh-gas and water. 
Nitrogen and the sulphur gases may be attributed in part to nitrides, 
sulphides, and basic sulphates. 
Many of these chemical reactions actually took place in the com- 
bustion tube during the process of extracting the gas from the rock 
material, and in some cases the larger part of the gas doubtless was 
