450 On the Fire-damp of Coal-mines, and on Methods 



greater capacity for heat, and probably, likewise, of a highe? 

 cotuluctiug power connected with its greater density. 



Tlie consideration of these various facts led me to adopt a 

 fjrni of a lamp, in which the flame by being suj~plied with onlv 

 a hmited quantity of air, should produce such a quantity of azote 

 and carbonic acid as to jnevent the explosion of the fire damp, 

 and which, by the nature of its apertures for giving admittance 

 and exit to the air, should be rendered incapable of communi- 

 cating anv explosion to the external air. 



If in a close lantern, supplied with a small aperture below 

 and another above, a lighted lamp having a very small wick be 

 placed, the natural flame gradually diminishes, till it arrives at a 

 point at which the supply of air is sufficient for the combustion 

 of a certain small quantity of oil ; if a lighted taper be intro- 

 duced into t!!e lantern through a small door in the side, which 

 rs instantly closed, both lights will burn for a few seconds, and 

 be extinguished tc>gether. 



A similar phsenon^enon occurs, if, in a close lantern, su|)plied 

 with a quantity of air merely sufficient to support a certain flame, 

 a mixture of fire danjp and air is gradually admitted : the first 

 effect of the fire-damp is to produce a larger flame round that 

 of the lamp, and this flame, consuming the oxygen which ought 

 to be su])plied to the flame of the lamp, and the standard of tl\e 

 power of the air to support flame being lowered bv the admix- 

 ture of fire-damp and by its rarefaction, both the flame of the 

 fire-damp and that of the taper are extinguished together ; and 

 as the air contained a certain quantity of azote and carbonic 

 acid before the admission of the fire-damp, their effect, by mixing 

 \vith it, is such as to prevent an explosion in any part of the 

 laiitern. 



I tried several experiments on the burning of a flame in at- 

 mospb.eres containing fire-damp. I inclosed a taper in a little 

 close lantern, having a small aperture below nnd a larger one 

 above, of such size that the taper burnt with a flame a little be- 

 low its natural size. I placed this lantern, the taper being 

 lighted, on a stand under a large glass receiver standing in 

 water, having a curved tube containing a little water, adapted to 

 itE top to confine the air, and which was of such a capacity a* 

 to enable the candle to burn for some minutes ; I then rapidly 

 threw a quantity of fire-damp into the receiver from a bladder, 

 8>o as to make the atmosphere in it explosive. As the fire-damp 

 mixed with the air, the flame of the taper gradually enlarged, 

 till it half filled the lantern ; it then rapidly diminished, and was 

 suddenly extinguished without the slightest explosion. I ex- 

 amined the air of the receiver after the experiment, and found 

 it highly explosive. 



I tried 



