VOL. LIX.] PHILOSOPHICAL TRANSACTIONS. 601 



of the powder, and the fragments have been seen red-hot for some time in dif- 

 ferent parts of the room, that the powder has not been fired, or only a few 

 grains of it, the rest being dispersed with great violence, part of it flying against 

 the faces of persons who assisted in making the experiments. This circumstance, 

 together with the charcoal being a conductor of electricity, makes it so ex- 

 tremely difficult to fire gunpowder by electrical explosions ; and it is evidently 

 owing to this lateral force, that parts of the melted wire fiy so many ways, and to 

 so great a distance from the place of explosion. 



This lateral force is exerted not only in the neighbourhood of an explosion, 

 when it is made betv.een pieces of metal in the open air, but also when it is 

 transmitted through wires that are not thick enough to conduct it perfectly ; and 

 the smaller the wire, and the more complete the fusion, the greater is the dis- 

 persion of light bodies placed near it. At one time, when the wire was not 

 melted, but turned blue by the explosion (in which case it generally assumes a 

 dusky red, which lasts but for a moment), there was a small dispersion from 

 every part of the wire, but by no means so great as it would have been if it had 

 been melted, or only heated to a greater degree. By a considerable number of 

 trials Dr. P. found, that a greater force of explosion would move light bodies at 

 a greater distance ; but the smaller the bodies were, the less was this difference ; 

 so that he supposed, that if they had no weight at all, they would probably be 

 moved at the same distance by the explosion from any quantity of coated sur- 

 face, charged equally high ; but there was a great difference in the weights re- 

 moved by different forces at the same distance. Placing the same piece of cork 

 at the same distance from the place of explosion, he found that the discharge of 

 one jar removed it -i-th of an inch, 2 jars Hth, three 14ths, and 4 about 2 

 inches ; so that he does not wonder at very heavy bodies being moved from their 

 places, and to considerable distances, by strong flashes of lightning. 



That the immediate cause of this dispersion of bodies in the neighbourhood 

 of electrical explosions, is not their being suddenly charged with a quantity of 

 electric matter, and therefore flying from others that are equally charged with it, 

 is, he thinks, evident from the following experiments and observations. He 

 never observed the least sensible attraction of these light bodies to the brass 

 rods, through which the explosion passed, or to the electric matter passing be- 

 tween them, previous to this repulsion, though he used several methods which 

 could not have failed to show it, if there had been any such thing. Sometimes 

 he suspended them in fine silken strings, and observed that they had contracted 

 no electricity after they had been agitated in the manner described above. Some- 

 times he dipped them in turpentine, and observed that no part of it was found 

 sticking either to the brass rods themselves, or to any part of the table between 

 them and the place where the light bodies had been laid. He even found that 



VOL. XII. 4 H 



