iio Faraday's Researches

platina, if they were made to replace the water, i.e. if the view
of independent action which I have taken (362, 363), as a con-
sequence of Dalton's principles, be correct. It would also seem
that the mutual relation of similar particles, and the indifference
of dissimilar particles which Dalton has established as a matter
of fact amongst gases and vapours, extends to a certain degree
amongst solids and fluids, that is, when they are in relation by
contact with vapours, either of their own substance or of other
bodies. But though I view these points as of great importance
with respect to the relations existing between different sub-
stances and their physical constitution in the solid, liquid, or
gaseous state, I have not sufficiently considered them to venture
any strong opinions or statements here.1

394. There are numerous well-known cases, in which sub-
stances, such, as oxygen and hydrogen, act readily in their
nascent state, and produce chemical changes which they are not
able to effect if once they have assumed the gaseous condition.
Such instances are very common at the poles of the voltaic pile,
and are, I think, easily accounted for, if it be considered that at
the moment of separation of any such particle it is entirely
surrounded by other particles of a different kind with which it is
in close contact, and has not yet assumed those relations and
conditions which it has in its fully developed state, and which it
can only assume by association with other particles of its own
kind. For, at the moment, its elasticity is absent, and it is in
the same relation to particles with which it is in contact, and
for which it has an affinity, as the particles of oxygen and
hydrogen are to each other on the surface of clean platina
(3^2, 363).

395. The singular effects of retardation produced by very
small quantities of some gases, and not by large quantities of
others (376, 381, 388), if dependent upon any relation of the
added gas to the surface of the solid, will then probably be found
immediately connected with the curious phenomena which are
presented by different gases when passing through narrow tubes
at low pressures, which I observed many years ago;2 and this
action of surfaces must, I think, influence the highly interesting
phenomena of the diffusion of gases, at least in the form in which
it has been experimented upon by Mr. Graham in 1829 and

1 In reference to this paragraph and also 362, see a correction by Dr. C.
Henry, in his valuable paper on this curious subject—Philosophical
Magazine, 1835, vol. vi. p. 365.—December 1838.

2 Quarterly Journal of Science, 1819, vol. vii. p. 106.833. If any part of the surface were