176 Mr. Howldy on the Electric Inflammation of Gunpowder. 



a perceptible time before the explosion of the residual charge 

 was heard. 



As the electric explosions in these experiments do not occur 

 till the gunpowder is in a state of combustion, it appears evi- 

 dent that either the product of the combustion, or the rare- 

 faction of the air by it, is the cause of this interesting pheno- 

 menon. For the conducting power of the interval is so aug- 

 mented, as to enable a portion of the charge having a lower 

 intensity, to pass with explosion over a distance which the 

 whole charge, having even a higher intensity, was incapable of 

 passing over, in the same time either with or without explo- 

 sion. This mode of inflaming gunpowder is related principally 

 on account of the interesting fact which was discovered in thus 

 conducting the experiment ; for it does not possess the facility 

 of the former, because it requires a nicer adjustment of the 

 distance forming the interruption with respect to the intensity 

 of the charge ; and the wooden point is generally so much 

 burned after two or three experiments have been made with 

 it, as to be rendered useless ; but as different ways of pro- 

 ducing the same effect are sometimes desirable and pleasing 

 as well as instructive, it may be recommended to the student 

 in electricity who wishes to become well acquainted with the 

 varieties of electrical action. 



The latest experiments which I have made to ascertain any 

 fact relative to the inflammation of gunpowder by electricity, 

 were made during the severe frost which occurred here last 

 winter. Previous to leaving the room in which the machine 

 and apparatus are kept and employed, one night during the 

 frost a saucer was placed upon the window-sill, and filled 

 with pure water, which was there left to be frozen. On the 

 following morning before any fire was lighted in the apartment, 

 the saucer, then containing a very hard mass of ice, was put 

 in the electrical circuit, and the interruption in which the gun- 

 powder was placed, was made upon the surface of the ice. 

 And when the charge of the small phial before described was 

 transmitted through the circuit, the gunpowder was immedi- 

 ately inflamed. The experiment was repeated, under similar 

 circumstances, the next morning, and the same effect ensued. 

 A small Fahrenheit's thermometer denoted the temperature of 

 the room, when these experiments were made, to be 30°* 



Mr. Sturgeon supposes that the velocity with which the 

 electric fluid moves, when the discharge passes through the 

 circuit with explosion, is the cause of the non-ignition of the 

 gunpowder placed in the circuit. 



" Hence," says he, " my first object now was to devise 

 some means of retarding the velocity of the electric fluid ; for 



I con- 



