256 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
PHYSIOLOGICAL EFFECTS. 
The gas produces the usual effects of suffocation. When present in small 
quantities a feeling of oppression and heaviness, with headache, is noted. In larger 
amounts the breathing and the pulse become rapid. If no fresh air is obtained 
collapse follows, often very suddenly and before the full extent of the danger is 
realized. The deaths due to gas have generally occurred in this way and not because 
the escape had been cut off. Nausea, vomiting, and pains in the back are common 
after-effects of a short visit to a gas-filled drift or winze. In some cases men have 
worked one or two days by electric light in places where candles woidd not burn; 
but in such cases utter exhaustion and possibly permanent injury followed. 
CONDITIONS OF OCCURRENCE. 
The miners soon ascertained that in the places affected the bad air was present 
and absent at intervals. The reason commonly assigned was the change of direction 
of the wind, high southwesterly winds being generally supposed to bring out the gas. 
In no mine were barometric observations carried on. While a local influence of 
winds on conditions of ventilation can not be denied, the relations of mine gases to 
barometric fluctuations, as established by investigations elsewhere, suggested an 
inquiry along these lines. A few observations in the Ophelia tunnel and in the 
Conundrum mine soon confirmed the hypothesis that the influx of gas takes place 
during low barometer and that the air is good during periods of high pressure. A 
series of observations extending over eight months was kindly and most efficiently 
carried out for us by Mr. B. F. Tipton, of the Conundrum mine, as recorded on 
page 264. In conjunction with our own data these records prove fairly well that the 
gases are subject to Kohler’s laws, primarily formulated for coal mines, which may 
be expressed as follows:® 
1. The influx of gas increases with falling barometer and decreases with rising 
barometer. 
2. The rapidity of the influx of gas is, roughly, proportional to the rate of 
decrease of pressure, and, conversely, the more rapidly the pressure increases the 
more rapidly the gas disappears. 
3. If a sudden fall of the barometer is followed by a longer period of low pressure 
the gas decreases slowly. If a sudden rise of the barometer is followed by a less 
rapid increase, or if the pressure remains constantly high, the quantity of gas will 
slowly increase. The largest or smallest amount of gas present does not, therefore, 
always correspond to the minimum or maximum of pressure. 
The records kept by Mr. Tipton show that in April and May, as well as in 
November and December, 1904, a great number of sharp fluctuations took place, the 
aneroid varying from 20.1 to 20.7 inches. One or two remarkable exceptions were 
noted. The gas was bad on April 23, with the high stand of 20.6 and a strong 
southwest wind. 
During the summer and fall, from June 9 to October 29, the barometer remained 
steadily at 20.4 to 20.5. During this period slow and curious fluctuations took 
place. From June 9 to August 4 the gas was continuously very troublesome. 
a Kohler, G., Lehrbuch der Bergbaukunde, 5th ed., Leipzig, 1900, p. 682. 
