152 Proceedings of Philosophical Socieiies. [FEx 
of gas, is erroneous. He considers the heat evolved by the com- 
bustion as the sole cause of the explosion. 
On Thursday, Jan. 16, Sir H. Davy’s paper on Flame was con- 
cluded. In the third part of his paper the author treats of the 
effect of different mixtures of other gaseous bodies on the combus- 
tibility of exploding compounds by the electric spark, He made a 
mixture of two volumes hydrogen and one volume oxygen gas, and 
tried the effect produced by adding various mixtures of other 
gaseous bodies. Olefiant gas was found to have the greatest effect 
in preventing the explosion of this mixture by electricity. The 
quantity of each gas necessary to prevent the explosion was diffe-- 
rent. From his experiments it appears that the effect does not de- 
pend upon the specific heat or the specific gravity of the gas added. 
He is of opinion that it depends chiefly upon the property of the gas 
to conduct heat. Gases, he thinks, differ as much in their con- 
ducting powers as solid bodies, and those which conduct best will 
act most powerfully in preventing explosion, by carrying off the 
heat, and cooling the mixture below the exploding point. 
The fourth part of the paper consisted in general remarks and 
practical inferences. He finds that neither the rarefaction nor con- 
densation of common air produces much effect upon flame burning 
init. The effect of wire-gauze in preventing explosions he con- 
siders as owing entirely to its property of carrying off the heat, and 
thus reducing the temperature of the gases that pass through it 
below the exploding point. He gave an account of various improve- 
ments introduced of late into the construction of the safe lamps for 
coal-mines, and pointed out advantages arising from the yielding 
nature of the wire-gauze, of which they are constructed. 
On Thursday, Jan. 23, a curious paper by Sir H. Davy was 
read, constituting an important addition to his preceding memoir. 
He had concluded from his former investigations that flame con- 
sisted of gaseous bodies heated above whiteness; and he had found 
that oxygen and hydrogen, as well as oxygen and charcoal, might be 
made to combine silently at a temperature below redness, and to 
form respectively water and carbonic acid. It occurred to him that 
during these combinations heat was given out, and that, though 
not sufficient to cause the explosion of the gaseous mixture, it 
might, notwithstanding, be able to heat a metallic body to redness 
While thinking of an experiment to determine this point, the phe- 
nomenon exhibited itself accidentally while he was making an ex- 
periment with a safe lamp in a mixture of carbureted hydrogen and 
air. He plunged the lighted safe lamp into this mixture, and then 
caused an additional quantity of carbureted hydrogen to pass into 
the mixture, The lamp was extinguished; but a platinum wire that 
was above the flame became red-hot, and continued so for several 
minutes ; and when it ceased to be luminous, the mixture had en- 
tirely lost its exploding properties. It was immediately obvious that 
the heat was evolved by the silent combination of the. carbureted 
hydrogen with the oxygen of the mixture; and that, though not 
