468 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. 



reverse direction to that produced by the action of the zinc in the arrangement ; and 

 after this has happened, the general current can pass through the whole of the system as 

 at first, but by its passage again restores the plates P^ and P' into the former opposing 

 condition. This, generally, is the fact described by Ritter, Marianini, and De la 

 Rive. It has great opposing influence on the action of a pile, especially if the latter 

 consist of but a small number of alternations, and has to pass its current through 

 many interpositions. It varies with the solution in which the interposed plates are 

 immersed, with the intensity of the current, the strength of the pile, the time of 

 action, and especially with accidental discharges of the plates by inadvertent contacts 

 or reversions of the plates during experiments, and must be carefully watched in 

 every endeavour to trace the source, strength, and variations of the voltaic current. 

 Its effect was avoided in the experiments already described (1036. &c.), by making 

 contact between the plates P' and P^ before the effect dependent upon the state of the 

 solution in contact with the zinc plate was observed, and by other precautions. 



1041. When an apparatus like fig. 26. (1017.) with several platina plates was used, 

 being connected with a battery able to force a current through them, the power 

 which they acquired, of producing a reverse current, was very considerable. 



1042. Weak and exhausted charges should never be used at the same time with 

 strong and fresh ones in the different cells of a trough, or the different troughs of a 

 battery : the fluid in all the cells should be alike, else the plates in the weaker cells, 

 in place of assisting, retard the passage of the electricity generated in, and transmit- 

 ted across, the stronger cells. Each zinc plate so circumstanced has to be assisted 

 in decomposing power before the whole current can pass between it and the liquid. 

 So that, if in a battery of fifty pair of plates, ten of the cells contain a weaker charge 

 than the others, it is as if ten decomposing plates were opposed to the transit of the 

 current of forty pairs of generating plates (1031.). Hence a serious loss of force, and 

 hence the reason why, if the ten pairs of plates were removed, the remaining forty pairs 

 would be much more powerful than the whole fifty. 



1043. Five similar troughs, of ten pairs of plates each, were prepared, four of them 

 with a good uniform charge of acid, and the fifth with the partially neutralized acid 

 of a used battery. Being arranged in right order, and connected with a volta-elec- 

 trometer (711.)? the whole fifty pairs of plates yielded 1*1 cubic inch of oxygen and 

 hydrogen in one minute : but on moving one of the connecting wires so that only 

 the four well-charged troughs should be included in the circuit, they produced 

 with the same volta-electrometer 8*4 cubical inches of gas in the same time. Nearly 

 seven eighths of the power of the four troughs had been lost, therefore, by their as- 

 sociation with the fifth trough. 



1044. The same battery of fifty pairs of plates, after being thus used, was connect- 

 ed with a volta-electrometer (711.), so that by quickly shifting the wires of commu- 

 nication, the current of the whole of the battery, or of any portion of it, could be 

 made to pass through the instrument for given portions of time in succession. The 



