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II. Experimental Researches in Electricity. — Sixteenth Series. 
By Michael Faraday, Esq., D.C.L. F.R.S. Fullerian Prof. Chem. Royal Insti- 
tution, Corr. Mernb. Royal and Imp. Acadd. of Sciences, Paris, Petersburgh, 
Florence, Copenhagen, Berlin, Gottingen, Modena, Stockholm, 8$c. Sfc. 
Received January 23, — Read February 6, 1840. 
§ 24 . On the source of power in the voltaic pile. 
f i. Exciting electrolytes, 8$c. being conductors of thermo and feeble currents. 
ii. Inactive conducting circles containing an electrolytic fluid. 
iii. Active circles excited by solution of sulphuret of potassium, fyc. 
§ 24 . On the source of power in the voltaic pile. 
1796. WHAT is the source of power in a voltaic pile? This question is at present 
of the utmost importance in the theory and to the development of electrical science. 
The opinions held respecting it are various ; but by far the most important are the 
two which respectively find the source of power in contact, and in chemical force. 
The question between them touches the first principles of electrical action ; for the 
opinions are in such contrast, that two men respectively adopting them are thence- 
forward constrained to differ, in every point, respecting the probable and intimate 
nature of the agent or force on which all the phenomena of the voltaic pile depend. 
1797. The theory of contact is the theory of Volta, the great discoverer of the 
voltaic pile itself, and it has been sustained since his day by a host of philosophers, 
amongst whom, in recent times, rank such men as Pfaff, Marianini, Fechner, 
Zamboni, Matteucci, Karsten, Bouchardat, and as to the excitement of the power, 
even Davy ; all bright stars in the exalted regions of science. The theory of chemi- 
cal action was first advanced by Fabroni*, Wollaston -f-, and Parrot^, and has been 
more or less developed since by CErsted, Becquerel, De la Rive, Ritchie, Pouillet, 
Schcenbein, and many others, amongst whom Becquerel ought to be distinguished 
as having contributed, from the first, a continually increasing mass of the strongest 
* A.D. 1792, 1799. Becquerel’s Traite de l’lilectricite, i. pp. 81 — 91, and Nicholson’s Quarto Journal, 
iii. 308. iv. 120, or Journal de Physique, vi. 348. 
t A.D. 1801. Philosophical Transactions, 1801, p. 427. 
+ A.D. 1801. Annales de Chimie, 1829, xlii. 45 ; 1831, xlvi. 361. 
