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III. Experimental Researches in Electricity. — Seventeenth Series. 
By Michael Faraday, Esq., D.C.L. F.RS. Fullerian Prof. Cliem. Royal Insti- 
tution, Corr. Memb. Royal and Imp. Acadd. of Sciences, Paris, Petersburgh, 
Florence, Copenhagen, Berlin, Gottingen, Modena, Stockholm, 8$c. 8$c. 
Received January 30, — Read March 19, 1840. 
§ 24. On the source of power in the voltaic pile. — (Continued.) 
iv. The exciting chemical force affected by temperature. 
v. The exciting chemical force affected by dilution. 
vi. Differences in the order of the metallic elements of voltaic circles. 
vii. Active voltaic circles and batteries without metallic contact. 
viii. Considerations of the sufficiency of chemical action. 
ix. Thermo-electric evidence. 
x. Improbable nature of the assumed contact force. 
iv. T'he exciting chemical force affected by temperature. 
1913. On the view that chemical force is the origin of the electric current in the 
voltaic circuit, it is important that we have the power of causing by ordinary chemical 
means, a variation of that force within certain limits, without involving any alteration 
of the metallic or even the other contacts in the circuit. Such variations should pro- 
duce corresponding voltaic effects, and it appeared not improbable that these dif- 
ferences alone might be made effective enough to produce currents without any me- 
tallic contact at all. 
1914. De la Rive has shown that the increased action of a pair of metals, when 
put into hot fluid instead of cold, is in a great measure due to the exaltation of the 
chemical affinity on that metal which was acted upon*. My object was to add to 
the argument by using but one metal and one fluid, so that the fluid might be alike 
at both contacts, but to exalt the chemical force at one only of the contacts by the 
action of heat. If such difference produced a current with circles which either did 
not generate a thermo current themselves, or could not conduct that of an antimony 
and bismuth element, it seemed probable that the effect would prove to be a result of 
pure chemical force, contact doing nothing. 
1915. The apparatus used was a glass tube (Plate III. fig. 7-) about five inches long 
* Annales de Chimie, 1828, xxxvii. p. 242. 
