ON THE TIME REQUIRED FOR IGNITION OF GUNPOWDER.
Gunpowder like all other inflammable substances requires to be raised to a certain temperature, before it will ignite, viz., to a dull red heat, or about 600° Fahrenheit. If the heat passes with such rapidity through the powder, so as not to raise the temperature to the necessary degree, then the powder will not ignite, from the velocity of transit, so that it might be possible to calculate theoretically, the velocity that must be given to a red hot ball to enable it to pass through a barrel of gunpowder without causing explosion. The passage of electric fluid through gunpowder may be adduced in evidence of the ignition being dependent on the degree of velocity. The flame of all fulminating powders will pass through the centre of a box filled with gunpowder without igniting one grain of it. If a train of gunpowder be crossed at right angles by a train of fulminating mercury, laid on a sheet of paper or a table, and the powder be lighted with a red hot iron wire, the flame will run on until it meets the cross train of fulminating mercury, when the inflammation of the latter will be so instantaneous as to cut off all connection with the continuous train of powder, leaving the remaining portion of the gunpowder unignited. If on the contrary the fulminating powder be lighted first, it will go straight on and pass through the train of gunpowder so rapidly, as not to inflame it at all. Were a gun to be charged with gun-cotton and gunpowder, the latter would be fired out unignited.