AND PREVENTING ITS EXPLOSION. 39 



sion. Thus coming barely within the verge of the power of 

 exploding, and owing it to these circumstances of quantity and 

 condensation, there is every probability, that if kindled in small 

 quantities it would not explode, and that, presented to an igni- 

 ted body much diluted and in a rarefied state, it would not 

 even inflame. Hence the chance of its inflaming in a lamp 

 such as that described, is inconsiderable, were it even admitted 

 to the flame ; and the certainty of its not exploding might al- 

 most be depended on. The security from this might even be 

 carried so far, by adapting properly the size of the upper aper- 

 ture, so as to produce the greatest degree of rarefaction in the 

 air, that if a mixture of the fire-damp with atmospheric air 

 were introduced, it might, instead of inflaming, become inca- 

 pable of supporting the combustion, or at least might so far 

 weaken the flame, as to give indication of the danger. 



Lastly, If even, from some singular cause, an explosion did 

 happen within the case of the lamp, it appears to me very 

 doubtful if it would be propagated farther. It must be ex- 

 tremely feeble. The flame or ignition could not be communi- 

 cated by the upper aperture to the air without, partly from its 

 smallness, and partly from the upper part of the lamp being 

 previously occupied by air not capable of kindling. Nor could 

 it be easily communicated downwards through the tube, espe- 

 cially in a flexible tube, the sides of which would first yield, 

 and then collapse ; and though conveyed downwards, there 

 would be little or no probability of an air occupying the floor 

 of the mine capable of being inflamed. The risk of such a 

 communication, if it were thought there were any, might pro- 

 bably also be diminished by conveying the air rather by seve- 

 ral small tubes than by one larger. Other contrivances suffi- 

 ciently simple, if they were supposed necessary, might be em- 

 ployed. A cup containing water, for example, or a saline so- 

 lution, 



