Professor Faraday on Gunpowder. 117 



chanical disposition of the grains. By this simple arrangement flame 

 might be made to traverse water ; the prepared fusee was coated over 

 with bituminous matter, to render it impermeable to water, and it 

 was then fit for use. This fact was beautifully illustrated by bending 

 a long piece of miner's fusee across a bath full of water, the two ends 

 of the fusee projecting over the opposite ends of the bath. A heated 

 wire was applied to one extremity, and the gunpowder continued to 

 burn slowly ; it traversed the water, and, after a short interval, the 

 combustion was made manifest by the appearance of flame at the 

 other end, and the entire consumption of the powder. 



The connecting pieces of the pyrotechnist were made alternately to 

 burn and explode on a similar principle. If a long narrow cylinder 

 of paper were filled with powder, and the gunpowder compressed 

 by tying the cylinder tightly at certain lengths, an alternate effect of 

 combustion and explosion resulted. This was experimentally shown. 

 The common cracker was another familiar instance, but here no 

 other means of compression were employed than that arising from 

 merely bending closely and firmly one part of the paper cylinder 

 on another. In each straight piece of cylinder there was explosion, 

 at each angle or bend there was combustion. The slow combustion 

 of powder by compression and consolidation, was made a source of 

 motion in the rocket, which consisted of a cylinder of compact pow- 

 der, enclosed in a case, and hollowed out in the centre by a conical 

 mass being plunged into it. This presented a much greater surface 

 than if merely one extremity was ignited ; and there was a propor- 

 tionately rapid evolution of gas, which, reacting on the air, caused 

 the rocket to ascend. 



It has been stated, that the explosion of grain gunpowder is gra- 

 dual and progressive ; hence its force on a projectile is measured by 

 the length of time which it has the power of reacting on it ; and 

 where resistance is offered for some time, the combustion is more 

 complete, and the quantity of gaseous matter evolved, greater. In 

 short-barrelled pieces the projectile is not carried far, and much of 

 the powder escapes combustion ; in long barrels these conditions are 

 reversed. This progressive explosion renders gunpowder more cer- 

 tain and regular in its effects than gun-cotton. A body which is 

 very suddenly explosive is apt to shatter the parts immediately in 



