72 Sir H. Davy’s researches on flame. 
of explosive mixtures at rest, will suffer them to pass when 
in rapid motion; but by increasing the cooling surface by 
diminishing the size, or increasing the depth of the aperture, 
ajl flames, however rapid their motion, may be arrested. 
Precisely the same law applies to explosions acting in close 
vessels : very minute apertures when they are only few in 
number will permit explosions to pass, which are arrested by 
much larger apertures when they fill a whole surface, A 
small aperture was drilled at the bottom of a wire-gauze 
lamp in the cylindrical ring which confines the wire-gauze ; 
this, though less than —§• of an inch in diameter, passed the 
flame and fired the external atmosphere, in consequence of 
the whole force of the explosion of the thin stratum of the 
mixture included within the cylinder driving the flame 
through the aperture; though, had the whole ring been 
composed of such apertures separated by wires, it would 
have been perfectly safe. 
Nothing can demonstrate more decidedly than these simple 
facts and observations, that the interruption of flame by solid 
tissues permeable to light and air, depends upon no recondite 
or mysterious cause, but to their cooling powers, simply con- 
sidered as such. 
When a light included in a cage of wire-gauze is intro- 
duced into an explosive atmosphere of fire-damp at rest, the 
maximum of heat is soon obtained, the radiating power of 
the wire, and the cooling effect of the atmosphere, more effi- 
cient from the mixture of inflammable air, prevents it from 
ever arriving at a temperature equal to that of dull redness. 
In rapid currents of explosive mixtures of fire-damp, which 
heat common gauze to a higher temperature, twilled gauze. 
