Resistance to Electrolysis

22 I

749. Three pairs of zinc and platina plates, fig. 54, were able
to produce a current which could pass an interposed platina
plate, and effect the electrolysation of water in cell iv. The
current was evident, both by the continued deflection of the
galvanometer, and the production of bubbles of oxygen and
hydrogen at the electrodes in cell iv. Hence the accumulated
surplus force of three plates of zinc, which are active in decom-
posing water, is more than equal, when added together, to the
force with which oxygen and hydrogen are combined in water,
and is sufficient to cause the separation of these elements from
each other.

Fig. 55-

750. The three pairs of zinc and platina plates were now
opposed by two intervening platina plates, fig. 55. In this case
the current was stopped.

751. Four pairs of zinc and platina plates were also neutral-
ised by two interposed platina plates, fig. 56.

752. Five pairs of zinc and platina, with two interposed
platina plates, fig. 57, gave a feeble current; there was per-
manent deflection at the galvanometer, and decomposition in
the cells vi and vn. But the current was very feeble; very

Fig. 57.

Fig. 58.

much less than when all the intermediate plates were remr
and the two extreme ones only retained: for when they
placed six inches asunder in one cell, they gave a po^
current. Hence five exciting pairs, with two interposed ob
ting plates, do not give a current at all comparable to tL
a single unobstructed pair.

753. I have already said that a very feeble current pas
when the series included one interposed platina and two pan effect