AND ON PREVENTING ITS EXPLOSION. 47 
holding in the hand a candle within a glass case, having a tube 
attached to it supplying air from near the floor. The supply 
of air to support the combustion being thus from beneath, the 
presence of carbonic acid gas to any hazardous extent would 
soon be discovered, by the flame of the lamp becoming fainter, 
and being at length extinguished, while the respiration of the 
individual would not be affected: And. by.raising the open 
end of the tube to different heights from the ground, the ex- 
tent to which the atmosphere of carbonic acid reached would 
be ascertained.» By establishing in mines in which the choak-. 
damp is liable to occur, a system of lighting similar to that 
which has been described, the danger from it would be effec. 
tually obviated... ) 
ik 
NOTES. 
