Identity of Electricities derived from different Sources, 163 



whether voltaic electricity in all cases merely eliminated, or 

 did not in some actually produce, the acid and alkali found 

 after its action upon water. The same necessity that urged 

 him to decide the doubtful point, which interfered with the 

 extension of his views, and destroyed the strictness of his rea- 

 soning, has obliged me to ascertain the identity or difference 

 of common and voltaic electricity. I have satisfied myself 

 that they are identical, and I hope the proofs I have to offer, 

 and the results flowing from them, will be found worthy the 

 attention of the Royal Society. 



267. The various phaenomena exhibited by electricity may, 

 for the purposes of comparison, be arranged under two heads ; 

 namely, those connected with electricity of tension, and those 

 belonging to electricity in motion. This distinction is taken 

 at present not as philosophical, but merely as convenient. 

 The effect of electricity of tension, at rest, is either attraction 

 or repulsion at sensible distances. The effects of electrical 

 currents may be considered as 1st, Evolution of heat; 2nd, 

 Magnetism ; 3rd, Chemical decomposition ; 4?th, Physiologi- 

 cal phaenomena ; 5th, Spark. It will be my object to com- 

 pare electricities from different sources, and especially com- 

 mon and voltaic electricities, by their power of producing 

 these effects. 



I. Voltaic Electricity. 



268. Tension. — When a voltaic battery of 100 pairs of 

 plates has its extremities examined by the ordinary electro- 

 meter, it is well known that they are found positive and nega- 

 tive, the gold leaves at the same extremity repelling each other, 

 the gold leaves at different extremities attracting each other, 

 even when half an inch or more of air intervenes. 



269. That ordinary electricity is discharged by points with 

 facility through air; that it is readily transmitted through 

 highly rarefied air ; and also through heated air, as for in- 

 stance a flame ; is due to its high tension. I sought, therefore, 

 for similar effects in the discharge of voltaic electricity, using 

 as a test of the passage of the electricity either the galvano- 

 meter or chemical action produced by the arrangement here- 

 after to be described (312. 316.). 



270. The voltaic battery I had at my disposal consisted of 

 140 pairs of plates four inches square, with double coppers. 

 It was insulated throughout, and diverged a gold leaf electro- 

 meter about one third of an inch. On endeavouring to dis- 

 charge this battery by delicate points very nicely arranged 

 and approximated, either in the air or in an exhausted re- 

 ceiver, I could obtain no indications of a current, either by 



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