196 ON THE WING. 



Combustion, to be available, must not be instanta- 

 neous. Time must be given for movement. Fulmi- 

 nating powder is, like lightning, more instantaneous 

 in its effect than gunpowder. It does not act, how- 

 ever, as a propellent force, as its combustion is so in- 

 stantaneous that no time is given for its environment 

 to expand. A gun charged with fulminating powder 

 would be apt to burst when ignited, on account of the 

 charge not moving quick enough to accommodate the 

 combustion. 



The same thing is true, to some extent, with very 

 fine-grained gunpowder, the combustion of which is 

 much more instantaneous than powder of a coarser 

 grain. Placed in a long-barrelled gun, it loses the 

 accelerating power produced by slow combustion, and 

 consequently its propellent force is greatly reduced, 

 while the recoil is increased. 



Greener quotes from a writer, who says : " If 

 a train of gunpowder be crossed at right angles by 

 a train of fulminating mercury, laid on a sheet of 

 paper on a table, and the gunpowder lighted by a 

 red-hot wire, the flame will run on until it meets the 

 cross train of fulminating mercury, when the inflam- 

 mation of the latter will be so instantaneous as to cut 

 off the connection with the continuous train of gun- 

 powder, leaving one half of the train unignited." And 

 again : " If the fulminating powder be lighted first, it 

 will go straight on, and pass through the train of gun- 

 powder so rapidly as not to inflame it at all." 



The explosive force of gunpowder, its pressure by 

 the force of the gases, and the general law of com- 



