_same_ nature (891. 904.). Those at the place of decomposition have a
re-action upon, and a power over, the exerting or determining set
proportionate to what is needful to overcome their own power; and hence a
curious result of _resistance_ offered by decompositions to the original
determining force, and consequently to the current. This is well shown in
the cases where such bodies as chloride of lead, iodide of lead, and water
would not decompose with the current produced by a single pair of zinc and
platina plates in sulphuric acid (903.), although they would with a current
of higher intensity produced by stronger chemical powers. In such cases no
sensible portion of the current passes (967.); the action is stopped; and I
am now of opinion that in the case of the law of conduction which I
described in the Fourth Series of these Researches (413.), the bodies which
are electrolytes in the fluid state cease to be such in the solid form,
because the attractions of the particles by which they are retained in
combination and in their relative position, are then too powerful for the
electric current[A]. The particles retain their places; and as
decomposition is prevented, the transmission of the electricity is
prevented also; and although a battery of many plates may be used, yet if
it be of that perfect kind which allows of no extraneous or indirect action
(1000.), the whole of the affinities concerned in the activity of that
battery are at the same time also suspended and counteracted.

[A] Refer onwards to 1705.--_Dec. 1838._

911. But referring to the _resistance_ of each single case of
decomposition, it would appear that as these differ in force according to
the affinities by which the elements in the substance tend to retain their
places, they also would supply cases constituting a series of degrees by
which to measure the initial intensities of simple voltaic or other
currents of electricity, and which, combined with the scale of intensities
determined by different degrees of _acting force_ (909.), would probably
include a sufficient set of differences to meet almost every important case
where a reference to intensity would be required.

912. According to the experiments I have already had occasion to make, I
find that the following bodies are electrolytic in the order in which I
have placed them, those which are first being decomposed by the current of
lowest intensity. These currents were always from a single pa