Mr. Howldy on the Electric Inflammation of Gunpowder. 173 



deferred till the return of summer shall afford me an oppor- 

 tunity of continuing them. 



From the results which have been stated, I am induced to 

 believe that the more refrangible rays of the solar spectrum 

 have a magnetic influence even in this country. 



XXV. On the Inflammation of Gunpowder by "Electricity. 

 By Mr. Thomas Howldy. 



To the Editor of the Philosophical Magazine and Journal. 

 Sir, 

 T^HROUGH the medium of your very useful Magazine and 

 - Journal, your ingenious correspondent Mr. Sturgeon has 

 communicated to the public, some observations and experi- 

 ments concerning the ignition of gunpowder by the charge of 

 a Leyden jar. But as Mr. Sturgeon's method of performing 

 the experiment is not so certain in its effect, nor more simple 

 than Cavallo's, and as a better than Cavallo's * does not seem 

 to have been yet made public, you will, perhaps, sir, favour 

 me by communicating to the cultivators of electrical science, 

 a method which I contrived more than twelve years ago, of in- 

 flaming with ease and certainty, either loose or confined gun- 

 powder by electricity ; especially as it saves the experimenter 

 time, labour, and power. 



By describing the manner in which the original experiment 

 was conducted, the method will immediately be understood, 

 and may be readily practised by any electrician. A jar, con- 

 taining about 160 square inches of (interior) coated surface, 

 was placed at the prime conductor, and the points of the wires 

 of the universal discharger were set upon the table of that 

 instrument, at the distance of one inch, and a quarter from 

 each other. A chain, which was laid upon the bare surface 

 of the table supporting the machine and apparatus, had one 

 of its extremities placed at the distance of four inches from 

 the bottom or outside of the jar; while its other extremity 

 was annexed to the negative end of the universal discharger. 

 By this arrangement, two interruptions were made in the 

 electrical circuit ; the first or that between the points of the 



* See his Elements of Natural or Experimental Philosophy, vol. iii. 

 page 411. It may be here stated, likewise, that both Mr. Tatum and Mr. 

 JLewthwaite, in their lectures on electricity delivered at the London Me- 

 chanics' Institution, had recourse to Cavallo's " water tube," as it is called 

 by the reporter of the lectures, in order to effect the experiment in ques- 

 tion. See the London Mechanics' Register, vol. i. p. 84, and vol. ii. p. 36. 



wires 



