260 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
the air the gas accumulates in raises and in the backs of the drifts. According to 
analysis by Mr. W. F. Edwards the gas contains 96.08 volumes nitrogen (by differ¬ 
ence) and 3.92 volumes oxygen. Xo carbon dioxide is present. 
In the cases of the Colorado and New Zealand mines mentioned it seems most 
probable that the carbon dioxide and the excess of nitrogen are exhalations from 
cooling magmas, as they are believed to be at Cripple Creek. 
DETAILED OBSERVATIONS AT CRIPPLE CREEK MINES. 
Eastern part of the district .—The large mines in the immediate vicinity of Victor, 
including the Portland, Stratton’s Independence, and adjacent properties, also 
the Golden Cycle, Vindicator, Hull City, Findley, Isabella, and Victor mines, are 
all practically free from the exhalations which in other parts of the district often 
cause inconvenience. In the Isabella mine the gas accumulated near the end of 
a long crosscut east on level 11. The same is true of a long crosscut toward the 
east on level 11 of the Findley mine; also, in the Golden Cycle, of a crosscut 900 feet 
long, which, near its breast, enters a particularly loose and open mass of breccia. 
The Hull City mine contained a few indications of gas. With these insignificant 
exceptions, no inconvenience has been caused by subterranean gases in the mines 
mentioned. 
Eclipse mine .—The Eclipse mine, situated immediately east of the Elkton, con¬ 
tains some gas. At the time of examination the shaft was filled with water to a 
point 224 feet below the collar. Above this the shaft was filled with gas, rendering 
the first level inaccessible. 
ETkton mine .—In the Elkton mine serious inconvenience is often experienced 
from gases which issue from fissures following the basic dike which traverses the 
property. At times the northern portion of the mine is almost filled with gas, 
especially in the lower levels. It is sometimes necessary to suspend work on this 
account. Xo gas was known above level 6 and until recently the work was not 
really interrupted by it. In the southern part of the mine, on level 7, gases issued 
in considerable quantities from an open crevice in the vein, which is here contained 
in granite, just outside of the boundary line of the breccia. A candle held up to 
this crevice in the roof of the drift would be immediately extinguished, and at 
times this vicinity is entirely inaccessible. A sample of the dry gas as it issues 
from the crevice was collected according to the method indicated on page 254 and 
an analysis gave the result shown on page 255. 
Moose mine .—A heavy gas is exceedingly troublesome in the Moose mine, 
particularly on the levels below 6, which communicate with the surface only 
through the main shaft. It issues copiously from the fissures in the breccia, par¬ 
ticularly from the shattered breccia on the 1,050-foot level, and it was only by 
lining the north drift of this level with sheet tin for a distance of over 600 feet 
that work in the north end was made possible. Powerful suction blowers were 
used to draw out the gas from the bottom level; but on stormy days, presumably 
at times when the barometric pressure is low, the gas pours into the mine, and the 
miners in several instances narrowly escaped suffocation. It is said that at such 
times, in spite of the adit connection in level 6, the gas has issued from the collar 
of the shaft in such abundance as to at once extinguish a candle. The gas collects 
