62 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XVI.) 
experimental evidence in proof that chemical action always evolves electricity* ; and 
De la Rive should be named as most clear and constant in his views, and most 
zealous in his production of facts and arguments, from the year 1827 to the present 
time-f. 
1798. Examining this question by the results of definite electro-chemical action, I 
felt constrained to take part with those who believed the origin of voltaic power to 
consist in chemical action alone (875. 965.), and ventured a paper on it in April 
1834^: (875, &c.), which obtained the especial notice of Marianini§. The rank of 
this philosopher, the observation of Fechner||, and the consciousness that over the 
greater part of Italy and Germany the contact theory still prevailed, have induced me 
to re-examine the question most carefully. I wished not merely to escape from error, 
but was anxious to convince myself of the truth of the contact theory ; for it was 
evident that if contact electromotive force had any existence, it must be a power not 
merely unlike every other natural power as to the phenomena it could produce, but 
also in the far higher points of limitation, definite force, and finite production (2065.). 
1799. I venture to hope that the experimental results and arguments which have 
been thus gathered may be useful to science. I fear the detail will be tedious, but 
that is a necessary consequence of the state of the subject. The contact theory has 
long had possession of men’s minds, is sustained by a great weight of authority, and 
for years had almost undisputed sway in some parts of Europe. If it be an error, it 
can only be rooted out by a great amount of forcible experimental evidence ; a fact 
sufficiently clear to my mind by the circumstance, that De la Rive’s papers have not 
already convinced the workers upon this subject. Hence the reason why I have 
thought it needful to add my further testimony to his and that of others, entering 
into detail and multiplying facts in a proportion far beyond any which would have 
been required for the proof and promulgation of a new scientific truth (2017-)- In 
so doing, I may occasionally be only enlarging, yet then I hope strengthening, what 
others, and especially De la Rive, have done. 
1800. It will tend to clear the question, if the various views of contact are first 
stated. Volta’s theory is, that the simple contact of conducting bodies causes elec- 
tricity to be developed at the point of contact without any change in nature of the 
bodies themselves ; and that though such conductors as water and aqueous fluids 
* A.D. 1824, &c. Annales de Chimie, 1824, xxv. 405; 1827, xxxv. 113; 1831, xlvi. 265, 276, 337, xlvii. 
113, xlix. 131. 
t Ibid. 1828, xxxvii. 225, xxxix. 297 ; 1836, lxii. 147 : or Memoires de Geneve, 1829, iv. 285 ; 1832, vi. 
149; 1835, vii. 
I Philosophical Transactions, 1834, p. 425. 
§ Memorie della Societa Italiana in Modena, 1837, xxi. p. 205. 
|| Philosophical Magazine, 1838, xiii. 205 ; or Poggendorf’s Annalen, xlii. p. 481. Fechner refers also to 
Pfaff’s reply to my paper. I never cease to regret that the German is a sealed language to me. 
