Source of Power in the Voltaic Pile  233
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 chemical action was
first advanced by Fabroni,1 Wollaston,2 and Parrot,3 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 contri-
buted, from the first, a continually increasing mass of the
strongest experimental evidence in proof that chemical action
always evolves electricity;4 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.5
 786.	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 (610, 700), and ventured a paper on it
in April, 1834 6 (610, etc.), which obtained the especial notice
of Marianini.7   The rank of this philosopher, the observation
of Fechner,8 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 (1053).
 787.	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 neces-
sary consequence of the state of the subject.   The contact
1	a.d. 1792, 1799.    Becquerel's Traite de VElectricite, i. pp. 81-91, and
Nicholson's Quarto Journal, iii. 308, iv. 120, or Journal de Physique, vi. 348.
2	a.d. 1801.    Philosophical Transactions, 1801, p. 427.
3	a.d. 1801.    Annales de Chimie, 1829, x^i- 45 >  I^3I, xlvi. 361.
4	a.d. 1824, etc.    Annales de Chimie, 1824, xxv. 405;  1827, xxxv. 113;
1831, xlvi. 265, 276, 337; xlvii. 113;  xlix. 131.
5	Ibid. 1828, xxxvii. 225;   xxxix. 297;   1836, Ixii. 147:   or Memoires de
Geneve, 1829, iv. 285;  1832, vi. 149;  1835, vii.
6	Philosophical Transactions, 1834, p. 425.
7	Memorie della Societa Italiana in Modena, 1837, xxi. p. 205.
8	Philosophical Magazine, 1838, xiii. 205; or Poggendorf s Annalcn, 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.