SUBTERRANEAN GASES. 
259 
Carbon dioxide is often very troublesome <in some of the deep alluvial mines 
at Creswick, just north of Ballarat, Victoria. In these mines the gravels of Ter¬ 
tiary river channels are extracted by means of shafts from 300 to 500 feet deep. 
The gravels are covered by thick basalt floors which have been erupted from many 
points in the district. As a rule these gravels contain only a small amount of 
organic matter. The occurrence of these gases has been carefully examined by 
Prof. A. Mica Smith, of the Ballarat School of Mines, who® finds that they issue most 
abundantly during periods of low barometer, that the gases are warmer than the 
normal air of the mine, and that they are heavily charged with moisture. The 
maximum amount of carbon dioxide found was 4.05 per cent, the highest nitrogen 
81.47 per cent, the minimum of oxygen 14.72 per cent. A typical analysis follows: 
Analysis of gas in mines at Creswiclc, Victoria. 
Carbon dioxide. 3.20 
Oxygen. 14. 72 
Nitrogen. 78. 78 
Water. 3. 30 
100.00 
A similar gas appears to be abundant in a great number of mines in the south¬ 
east section of the main Gilpin County district of gold-silver veins. 6 The deposits 
occur in pre-Cambrian gneiss with dikes and masses of andesitic rocks. The gas, 
which is partly, at least, composed of carbon dioxide, issues suddenly in great 
volumes during periods of low barometer and especially following a sudden decrease 
l the barometric pressure. Several fatal accidents are due to the presence of 
his gas. It is heavy and fills shafts and winzes up to a sharply defined line. 
Mr. J. E. Spurr states 0 that pockets of a gas which evidently consisted of 
carbon dioxide were opened in the Tonopah mines at relatively shallow depths. 
The deposits consist of gold- and silver-bearing fissure veins in andesite rocks. 
A heavy gas, probably chiefly carbon dioxide, is very abundant and trouble¬ 
some in the shafts near Rico, Colo. d 
There are few accounts of the presence of nitrogen gas in mines. Only one 
occurrence is quoted in the general literature; it is at the Strinesdale tunnel near 
Stockport, England/ It consisted of 92 volumes of nitrogen, 8 volumes of oxygen, 
and a trace of carbon dioxide. An important occurrence has lately been described 
by Mr. Harry A. Lee, of Denver/ The locality is Creede, a mining district in 
Colorado containing silver veins in Tertiary volcanic rocks. The Happy Thought 
mine is working on a great fault fissure on which a number of other well-known 
mines are also located. The shaft is 1,400 feet deep and the natural ventilation 
excellent. The gas at times issues in great abundance from the vein; the changes 
appear to accord with barometric variations. Nitrogen being slightly lighter than 
a Smith, A. Mica, Report on the foul air of the Allendale mines: Special Rept. Dept, of Mines, Melbourne 1892, p. 24. 
b Collins, Arthur L., Note on the occurrence of carbonic-acid gas in certain veins of Gilpin County, Colo.: Proc. Colorado 
Soi. Soc., vol. 6, 1897-1900, pp. 120-123. 
c Oral communication. 
d Ransome, F. L., Ore deposits of the Rico Mountains, Colorado: Twenty-second Ann. Rept. U. S. Geol. Survey, pt. 2, 
1901, pp. 304, 305. 
* Foster, C. Le Neve, Ore and Stone Mining, 2d ed., London, 1897, p. 479. 
/ Gases in metalliferous mines: Proc. Colorado Sci. Soc., vol. 7, 1897-1900, pp. 163-192. 
