42 Dr. Faraday*s Experimental Researches in Electricity, 



affinities and the acting affinities thus exalted. This expec- 

 tation was fully confirmed in the following manner. 



906. A little nitric acid was added to the liquid in the ves- 

 sel i;, so as to make a mixture which I shall call diluted nitro- 

 sulphuric acid. On repeating the experiments with this mix- 

 ture, all the substances before decomposed again gave way, 

 and much more readily. But besides that, many which before 

 resisted electrolyzation now yielded up their elements. Thus, 

 solution of sulphate of soda, acted upon in the interstices of 

 litmus and turmeric paper, yielded acid at the anode and al- 

 kali at the cathode ; solution of muriatic acid tinged by indigo 

 yielded chlorine at the anode, and hydrogen at the cathode ; so- 

 lution of nitrate of silver yielded silver at the cathode. Again, 

 fused nitre and the fused iodide and chloride of lead were 

 decomposable by the current of this single pair of plates 

 though they were not by the former (903.). 



907. A solution of acetate of lead was apparently not de- 

 composed by this pair, nor did water acidulated by sulphuric 

 acid seem at first to give way (973.). 



908. The increase of intensity or power of the current pro- 

 duced by a simple voltaic circle, with the increase of the force 

 of the chemical action at the exciting place, is here sufficiently 

 evident. But in order to place it in a clearer point of view, 

 and to show that the decomposing effect was not at all de- 

 pendent, in the latter cases, upon the mere capability of evolv- 

 ing more electricity, experiments were made in which the 

 quantity evolved could be increased without variation in the 

 intensity of the exciting cause. Thus the experiments in which 

 dilute sulphuric acid was used (899.) were repeated, using 

 large plates of zinc and platina in the acid; but still those 

 bodies which resisted decomposition before, resisted it also 

 under these new circumstances. Then again, where nitro-sul- 

 phuric acid was used (906.), mere wires of platina and zinc 

 were immersed in the exciting acid; yet, notwithstanding this 

 change, those bodies were now decomposed which resisted 

 any current tending to be formed by the dilute sulphuric acid. 

 For instance, muriatic acid could not be decomposed by a 

 single pair of plates when immersed in dilute sulphuric acid ; 

 nor did making the sulphuric acid strong, nor enlarging the 

 size of the zinc and platina plates immersed in it, increase the 

 power ; but if to a weak sulphuric acid a very little nitric acid 

 was added, then the electricity evolved had power to decom- 

 pose the muriatic acid, evolving chlorine at the anode and hy- 

 drogen at the cathode, even when mere wires of metals were 

 used. This mode of increasing the intensity of the electric 

 current, as it excludes the effect dependent upon many pairs 

 of plates, or even the effect of making any one acid stronger 



