PROCEEDINGS 



THE ROYAL IRISH ACADEMY. 



1846-7. No. 67. 



May 24th, 1847. 



REV. WILLIAM HAMILTON DRUMMOND, D. D., 



Librarian, in the Chair. 



M. Donovan, Esq., continued the reading of his paper on 

 the Nature of the Agency which produces the Effects called 

 Galvanic, Electro-magnetic, Magneto-electric, and Thermo- 

 electric. 



The next subject to which Mr. Donovan called the atten- 

 tion of the Academy was the instantaneous charge which a 

 Leyden battery receives by a momentary contact with an ex- 

 tensive voltaic series. This has been always adduced as an 

 argument in support of the affirmed enormous quantity of 

 electricity which constitutes the voltaic current. Van Marum 

 charged a Leyden battery of twenty-five jars by a momentary 

 connexion with a pile consisting of silver coins and zinc discs, 

 one inch and a half in diameter. The battery and pile were 

 thus charged to the same intensity, so feebly, however, as to 

 produce divergence in a gold leaf electrometer to the extent 

 of five-eighths of an inch ; but the shock from the battery was 

 only equivalent to halt that of the pile. Facts and calcula- 

 tions were adduced to show that the charge of electricity in 

 this Leyden battery, when thus charged, could not have ex- 

 ceeded the quantity of two or three one-inch sparks. Sir H. 



VOL. III. 2 T 



