480 Royal Society. 
2072. It should ever be remembered that the chemical theory 
sets out with a power, the existence of whichis pre-proved, and 
then follows its variations, rarely assuming anything which is 
not supported by some corresponding simple chemical fact. - 
The contact theory sets out with an assumption, to which it 
adds others as the cases require, until at last the contact force, 
instead of being the firm unchangeable thing at first supposed 
by Volta, is as variable as chemical force itself. 
2073. Were it otherwise than it is, and were the contact 
theory true, then, as it appears to me, the equality of cause 
and effect must be denied (2069.). Then would the perpetual 
motion also be true; and it would not be at all difficult, upon 
the first given case of an electric current by contact alone, to 
produce an electro-magnetic arrangement, which, as to its 
principle, would go on producing mechanical effects for ever. 
Royal Institution, Dec. 26, 1839. 
LXXXII. Proceedings of Learned Societies. 
ROYAL SOCIETY. 
[Continued from p. 157.] 
December 8, 1842.—The following papers were read, viz. :— 
“ Observations on the Blood-corpuseles, particularly with refer- 
ence to opinions expressed and conclusions drawn in papers ‘ On 
the Corpuscles of the Blood,’ and ‘On Fibre,’ recently published 
in the Philosophical Transactions.” By T. Wharton Jones, Esq., 
F.R.S. ; 
The author points out what he considers to be important errors in 
the series of papers by Dr. Martin Barry, which have lately appeared 
in the Philosophical Transactions, and are entitled, “ On the Corpus- 
cles of the Blood,” and “ On Fibre*.” He alleges that Dr. Barry has 
but the striking passage I desire now to refer to, is the following, at § 113. 
of the article Galvanism. Speaking of the voltaic theory of contact, he 
says, ‘“‘ Were any further reasoning necessary to overthrow it, a forcible 
argument might be drawn from the following consideration. If there 
could exist a power having the property ascribed to it by the hypothesis, 
namely, that of giving continual impulse to a fluid in one constant direc- 
tion, without being exhausted by its own action, it would differ essentially 
from all the other known powers in nature. All the powers and sources of 
motion, with the operation of which we are acquainted, when producing 
their peculiar effects, are expended in the same proportion as those effects 
are produced; and hence arises the impossibility of obtaining by their 
agency a perpetual effect; or, in other words, a perpetual motion. But 
the electromotive force ascribed by Volta to the metals when in contact, is 
a force which, as long as a free course is allowed to the electricity it sets 
in motion, is never expended, and continues to be excited with undimi- 
nished power, in the production of a never-ceasing effect. Against the 
truth of such a supposition, the probabilities are all but infinite.’—Rocer, 
* See Phil. Mag., S. 3. vol. xx. pp. 321, 344; vol. xxi. p. 220.—Enprr. 
