844? Dr. F{iraday*s Experimental Researches in Electricitif, 



meter. This current I believe to be due to electricity reduced 

 in intensity below the point requisite for the decomposition of 

 water (970. QS^.); 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 under this intensity, it is probable that in- 

 creasing the number of interposed platina plates would not 

 involve an increased difficulty of conduction. 



1018. In order to obtain an idea of the additional interfer- 

 ing power of each added platina plate, six voltaic pairs and 

 four intervening platinas were arranged as in fig. 27 ; 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 re- 

 tarded the current more powerfully than the second, and the 

 second more than the third. 



1019. In these experiments both amalgamated and un- 

 amalgamated zinc were used, but the results generally were 

 the same. 



1020. The effects of retardation just described were altered 

 altogether when changes were made in the nature of the liquid 

 used between the plates, either in what may be called the ex- 

 citing or the retarding cells. Thus, retaining the exciting 

 force the same, by still using pure dilute sulphuric acid for 

 that purpose, if a little nitric acid were added to the liquid in 

 the retarding cells, then the transmission of the current was 

 very much facilitated. For instance, in the experiment with 

 one pair of exciting plates and one intervening plate (1011.), 

 fig. 20, when a few drops of nitric acid were added to the 

 contents of cell ii, then the current of electricity passed with 

 considerable strength (though it soon fell from other causes 

 (1036. 104<0.),) and the same good effect was produced by 

 the nitric acid when many interposed plates were used. 



1021. This seems to be a consequence of the diminution of 

 the difficulty of decomposing water when its hydrogen, as in 

 these cases, instead of being absolutely expelled, is transferred 

 to the oxygen of the nitric acid, producing a secondary result 

 at the cathode (752.) ; for in accordance with the chemical 

 views of the electric current and its action already advanced 

 (913.), the water, instead of opposing a resistance to decom- 



