io Sir Humphry Davy on the fire-damp of coal mines , and on 
of a higher conducting power connected with its greater 
density. 
The consideration of these various facts, led me to adopt a 
form of a lamp, in which the flame, by being supplied with 
only a limited quantity of air, should produce such a quantity 
of azote and carbonic acid, as to prevent 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 communicating any 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 introduced into the lantern through a small door in 
the side, which is instantly closed, both lights will burn for a 
few seconds, and be extinguished together. 
A similar phenomenon occurs, if, in a close lantern, supplied 
with a quantity of air merely sufficient to support a certain 
flame, a mixture of fire-damp 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 oxy- 
gene which ought to be supplied to the flame of the lamp, 
and the standard of the power of the air to support flame being 
lowered by the admixture of fire-damp and by its rarefaction, 
both the flame of the fire-damp and that of the taper are extin- 
guished 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 with it, is such as to prevent an 
explosion in any part of the lantern. 
