1014.  The three pairs of zinc and platina plates were now opposed by two intervening platina plates, fig. 95.  In this case the current was stopped.

1015.  Four pairs of zinc and platina plates were also neutralized by two interposed platina plates, fig. 96.

1016.  Five pairs of zinc and platina, with two interposed platina plates, fig. 97, gave a feeble current; there was permanent deflection at the galvanometer, and decomposition in the cells vi and vii.  But the current was very feeble; very much less than when all the intermediate plates were removed and the two extreme ones only retained:  for when they were placed six inches asunder in one cell, they gave a powerful current.  Hence five exciting pairs, with two interposed obstructing plates, do not give a current at all comparable to that of a single unobstructed pair.

1017.  I have already said that a very feeble current passed when the series included one interposed platina and two pairs of zinc and platina plates (1012.).  A similarly feeble current passed in every case, and even when only one exciting pair and four intervening platina plates were used, fig. 98, a current passed which could be detected at x, both by chemical action on the solution of iodide of potassium, and by the galvanometer.  This current I believe to be due to electricity reduced in intensity below the point requisite for the decomposition of water (970. 984.); for water can conduct electricity of such low intensity by the same kind of power which it possesses in common with metals and charcoal, though it cannot conduct electricity of higher intensity without suffering decomposition, and then opposing a new force consequent thereon.  With an electric current of, or under this intensity, it is probable that increasing the number of interposed platina plates would not involve an increased difficulty of conduction.

1018.  In order to obtain an idea of the additional interfering power of each added platina plate, six voltaic pairs and four intervening platinas were arranged as in fig. 99; a very feeble current then passed (985. 1017.).  When one of the platinas was removed so that three intervened, a current somewhat stronger passed.  With two intervening platinas a still stronger current passed; and with only one intervening platina a very fair current was obtained.  But the effect of the successive plates, taken in the order of their interposition, was very different, as might be expected; for the first retarded the current more powerfully than the second, and the second more than the third.

1019.  In these experiments both amalgamated and unamalgamated zinc were used, but the results generally were the same.