120 On Lighting Coal Mines. (Fes. 
of temperature, produced by the contact, and absorbing. oxygen 
from the air, suffer combustion, and an exaltation of temperature even 
to white heat. If, therefore, the collision be made in atmospheric air, 
combustion of the steel takes place. If in pure hydrogen gas neither 
combustion of the steel, nor explosion of the gas, takes place, for 
want of a due commixture of oxygen. If the collision be made in 
a due mixture of oxygen and hydrogen gases, will not both combus- 
tion of the steel first, and consequent explosion of the gas, be pro- 
duced? Perfect safety is not, therefore, to be expected from the 
use of these instruments, but this developement of the danger in 
its principles leads to this practical improvement in the machine. 
The chance of danger may be diminished by a construction that 
shall subject the steel only to close contact without any separation 
of parts, leaving all abrasions to be of the parts of flint which are 
incapable of further exaltation of temperature. 
Sir H. Davy’s lantern diminishing the supply of atmospheric air by 
adjustment of the apertures through which alone it enters and passes 
out, diminishes the flame. Admit hydrogen gas pure or not sufficiently 
mixed with atmospheric air, to explode ; the pure gas will burn with- 
out explosion, as it does in the lamps of the metropolis, and goes out, 
as it would in those lamps if the supply of fresh air were excluded 
from all other entrance, and. by the gas itself where it enters. A 
non-explodible mixture of gases burns in the lantern, as it does at 
the taper of the miner, who, when he sees the flame capped with a 
surrounding flame, knows his danger, gently depresses his candle 
into a lower stratum of air, and retires. . The lantern does nothing 
for him which his own observation of his candle does not; and if 
the flame of the lamp will thus fire this non-explodible mixture of 
the gases, what is there to prevent the inflammation and explosion 
of explodible mixtures, and the communication of the flame through 
the apertures of the lantern with that body of mixed gases which is 
external and adjacent? The lantern, therefore, will not explode 
non-explodible gases, and will not fail to explode explodible gases. 
Various other considerations present themselves in opposition to 
the use of this lantern. The flame, it is supposed, renders, as it 
burns, the air in the lantern less fit for combustion, by portions of 
azote and carbonic acid gases which mix therewith. If in the first 
minute a given portion of these airs be mixed with the air in the 
lantern ; in the second minute, another ; and in the third, and other 
succeeding minutes, successive rateable portions; the power of 
combustion must end, and the flame be gradually extinguished. 
This difficulty can only be surmounted by an adjustment of aper- 
tures, which supposes or renders this successive deoxygenation sub- 
ject to certain limits of existence? If from this supposed period 
we reason back, will not the agency of the same causes which at 
any time prevent, always prevent, any deoxygenation, even at the 
commencement of the inflammation; and does- not all this prove 
that the reduced state of the flame observed in the lantern depends 
upon some other cause rather than the quality of the air? 
