THE NATIONAL GEOGRAPHIC MAGAZINE 



417 



THE THREE DEADLY 

 MINE GASES 



The three principal 

 gases encountered in 

 mines are choke-damp, 

 or carbonic acid gas ; 

 fire - damp, or marsh 

 gas; and after-damp, 

 or carbonic oxide gas. 

 Choke-damp is heavier 

 than air and settles in 

 the lower parts of a 

 mine, just as water 

 seeks the lowest level. 

 It kills by suffocation. 

 It may be dipped up 

 with a bucket like 

 water, and its pres- 

 ence may be detected 

 by lowering a light into 

 the cavity where it ex- 

 ists, as it will put out 

 the flame immediately. 

 Individual miners are 

 killed by it, but it 

 never explodes. 



Fire-damp is a most 

 peculiar gas. If you 

 mix less than 85 per 

 cent of air with it or 

 more than 95 per cent 

 of air, it will burn but 

 will not explode; but 

 if it be mixed in the 

 proportion of 88 or 

 89 parts air to 11 or 

 12 of fire-damp, the 

 combination becomes 

 one of the most terri- 

 ble of explosives. 



Eternal watch f u 1- 

 ness is the price of 

 safety. When the coal is blasted down, 

 fire-damp pockets are often opened up, 

 and the thin, trickling, hissing sound tells 

 the miner what has occurred. Miners 

 test the chambers, headings, and entries 

 for fire-damp with a lamp. If the blaze 

 becomes elongated and blue at the base, 

 that gas is present. 



An explosion of fire-damp is one of the 

 most terrible disasters that can occur in 

 a mine. In an instant the dark, man- 

 made caverns are lighted up from end to 

 end by a lightning that beggars descrip- 



Photograph from U. S. Bureau of Mines 



HOW NOT TO PREPARE A BLAST 



This miner, pouring powder out of a jagged, pick-cut hole in his 

 can, while his cap lamp burns brightly, is not only taking a chance 

 with his own life, but with that of every other miner in the work- 

 ings. This is a picture of what the miner should not do. But 

 thousands of lives have been sacrificed by just such methods. 



tion. "The expanded gas drives before 

 it a roaring whirlwind of blazing air," 

 as one who has survived the catastrophe 

 tells us, "which tears up everything in its 

 progress, burning many a miner's body to 

 cinders, entombing others, and, rushing 

 to the shaft, it wastes its fury in the 

 shower of dust and stones and timbers it 

 blows high into the air." 



A tragic story might be written of mine 

 disasters which fire-damp has caused and 

 of the tens of thousands of miners who 

 have given up their lives in such holo- 



