methods of lighting the mines without producing its explosion, g 
by metallic tubes of j of an inch,* when they were l^inch 
long; and this phenomenon probably depends upon the heat 
lost during the explosion in contact with so great a cooling 
surface, which brings the temperature of the first portions 
exploded below that required for the firing of the other por- 
tions. Metal is a better conductor of heat than glass : and it 
has been already shown that the fire-damp requires a very 
strong heat for its inflammation. 
Mixture of the gas with air I found, likewise, would not 
explode in metallic canals or troughs, when their diameter 
was less than the \ 0 f an inch, and their depth considerable 
in proportion to their diameter ; nor could explosions be 
made to pass through such canals. 
Explosions likewise I found would not pass through very 
fine wire sieves or wire gauze. 
I mixed azote and carbonic acid in different quantities with 
explosive mixtures of fire-damp, and I found that even in very 
small proportions they diminished the velocity of the inflam- 
mation. Azote, when mixed in the proportion of 1 to 6 of 
an explosive mixture, containing 12 of air and 1 of fire-damp, 
deprived it of its power of explosion ; when 1 part of azote 
was mixed with 7 of an explosive mixture, only a feeble 
blue flame slowly passed through the mixture. 
1 part of carbonic acid to 7 of an explosive mixture de- 
prived it of the power of exploding; so that its effects are 
more remarkable than those of azote ; probably, in conse- 
quence of its greater capacity for heat, and probably, likewise, 
* I do not give this result as perfectly exact, as the bore of the metallic tube had 
not the same polish as that of the tube of glass. 
c 
MDCCCXVI. 
