174- Mr. Howldy on the Inflammation 



wires was, as usual, intended to receive the substance which 

 was to be subjected to the action of the charge ; and the se- 

 cond, or that between the end of the chain and the outside of 

 the jar, was intended to diminish the intensity of the charge, 

 so as to prevent the electrical explosion from occurring in the 

 first interruption. A little heap of gunpowder was then laid 

 at the point of each wire, so as to surround and cover it ; a 

 small train of the same being laid to connect the heaps. 



A moderate charge was then transmitted through the cir- 

 cuit, and the gunpowder was instantly inflamed by its trans- 

 mission. 



Having repeated the experiment several times, the distances 

 in the interruptions being the same, the desired effect was al- 

 ways produced with the same intensity of the charge ; and in 

 pursuing the subject further, it was likewise found that the 

 experiment succeeded when the distances were varied within 

 certain limits, unless the intensity of the charge was conside- 

 rably too great or too small. When the charge, in a few in- 

 stances, was too intense, on its transmission a spark was seen 

 darting between the two points, which disturbed, in a small 

 degree, some of the gunpowder, without inflaming it; but 

 when, in the subsequent experiment, the charge was less in- 

 tense, its transmission caused the immediate inflammation of 

 the gunpowder. Hitherto the gunpowder had been invariably 

 disposed of in the interruption, as described in the original 

 experiment ; but I now wished to ascertain whether it would 

 be inflamed when placed in a single heap in any part of the 

 interruption, every other part being free from it. On trial it 

 was discovered that whether the gunpowder was placed in a 

 heap at either the positive or negative wire, or in the middle 

 of the interruption, or in any other part of it, the passage 

 of the charge, through the interruption, always inflamed it, 

 though in each instance the rest of the interruption was en- 

 tirely free from gunpowder. 



During the performance of the preceding and many other 

 experiments of the kind, which it is unnecessary to detail, it 

 was observed on several occasions, that only a small portion 

 of the charge was transmitted through the circuit, and conse- 

 quently that a considerable portion of it remained in the jar ; 

 and yet the gunpowder in such cases was always inflamed. 

 This circumstance led me to infer that the charge of a smaller 

 jar might be successfully employed for the experiment. In 

 consequence of which a jar whose coated surface measured 

 half a square foot was placed at the conductor, and the trans- 

 mission of its charge inflamed the gunpowder as readily as 



that 



