[ 4.10 ] 



LXIV. Experimental Researches in Electricity, — Eighth Se- 

 ries, By Michael Faraday, D,C.L.F,R.S.Fullerian Prof, 

 Chem, Royal Institutio7i, Corr, Memh. Royal and Imp. Acadd. 

 of Sciences^ Paris, Petersburgh, Florence, Copenhagen, Ber- 

 lin, &)C. Sfc. 



[Continued from p. 348, and concluded.] 



f V. General Remarks 07i the active Voltaic Battery. 



lOS*. 'l^HEN the ordinary voltaic battery is brought into 

 ^^ action, its very activity produces certain effects, 

 which re-act upon it, and cause serious deterioration of its 

 power. These render it an exceedingly inconstant instru- 

 ment as to the quantity of effect which it is capable of pro- 

 ducing. They are already, in part, known and understood ; 

 but as their importance, and that of certain other coincident 

 results, will be more evident by reference to the principles and 

 experiments already stated and described, I have thought it 

 would be useful, in this investigation of the voltaic pile, to 

 notice them briefly here. 



1035. When the battery is in action, it causes such sub- 

 stances to be formed and arrayed in contact with the plates 

 as very much weaken its power, or even tend to produce a 

 counter current. They are considered by Sir Humphry Davy 

 as sufficient to account for the phaenomena of Ritter's second- 

 ary piles, and also for the effects observed by M. A. De la Rive 

 with interposed platina plates *. 



1036. I have already referred to this consequence (1003.), 

 as capable, in some cases, of lowering the force of the current 

 to one eighth or one tenth of what it was at the first moment, 

 and have met with instances in which its interference was very 

 great. In an experiment in which one voltaic pair and one 

 interposed platina plate were used with dilute sulphuric acid 

 in the cells (fig. 31.), the wires of communication were so ar- 

 ranged, that the end of that marked 3 could be placed at 

 pleasure upon paper moistened in the solution of iodide of 

 potassium at x, or directly upon the platina plate there. If, 

 after an interval during which the circuit had not been com- 

 plete, the wire 3 were placed upon the paper, there was evi- 

 dence of a current, decomposition ensued, and the galvano- 

 meter was affected. If the wire 3 were made to touch the 

 metal of jj, a comparatively strong sudden current was pro- 

 duced, affecting the galvanometer, but lasting only for a mo- 

 ment; the effect at the galvanometer ceased, and if the wire 

 3 were placed on the paper at x, no signs of decomposition 

 occurred. On raising the wire 3, and breaking the circuit 



* Philosophical Transactions, 1826, p. 413. [or Phil. Mag. and Annals, 

 N.S., vol. i. p. 193.— Edit.] 



