Mr. Grove on the Electro-chemical Polarity of Gases. 509 



Faraday observes, Experimental Researches, 1164, "In an 

 electrolyte induction is the first state, and decomposition the 

 second." My present experiments show, I beheve, that in induc- 

 tion across gaseous dielectrics there is a commencement, so to 

 speak, of decomposition, a polar arrangement not merely of the 

 molecules, irrespective of their chemical characters, but a che- 

 mical alternation of their forces, the electro-negative element 

 being determined or directed, though not travelling in one direc- 

 tion, and the electro-positive in the opposite direction. 



This arrangement is only evidenced at present, as it is in 

 electrolysis, by the action at the polar extremities or termini of 

 the dielectric; possibly future researches may show, by the 

 action of polarized light, by magnetism or some other means of 

 analysis, that the polarity extends, as we theoretically believe it 

 does, through the whole intervening matter. 



In the Experiment No. 5 with oxygen and excess of nitrogen, 

 reduction takes place by the effect of negative electricity and 

 heat, at least there seems every reason from analogy to believe 

 that the effect of the nitrogen is only negative, protecting the 

 plate from oxygen, or at furthest catalytic, aiding the reduction 

 as sulphuric acid aids the electrolysis of water. Upon the state 

 of association of the gases in what is generally called mixture, I 

 venture an opinion with the greatest diffidence. I have always 

 inclined to the opinion that the difference between physical ad- 

 mixture, as it is termed, of gases and chemical union, is one of 

 degree, and the views of Dalton ever presented to my mind grave 

 difficulties*. My present results seem to me in favour of the 

 chemical view, as otherwise we can scarcely imagine electricity 

 as effecting in the instances given a merely physical separation j 

 it may indeed be said that there is composition and decomposition 

 produced by the same discharge ; but this is very difficult to 

 conceive, and can hardly apply to the cases of oxygen with 

 nitrogen and of carbonic oxide. 



In the experiments I have detailed, the flame or visible effect 

 of the electric discharge coincided with the chemical effect ; when 

 the plate was positive, a small globule of flame of a purj)le colour 

 was visible on the part of tlie plate attacked, and a bluish flame 

 extended over an inch or more of the needle. When the plate 

 was negative, a wider and less-defined disc of blue flame extended 

 over the part of the ])late opposed to the positive point, like a 

 sj)]asli of li(juid thrown u])on it, and a pencil of light apj)eared 

 on the ])oint. Sometimes, but not always, this flame avoided 

 the oxidated jjortion, probal)ly from its inferior conducting 

 j)ower; and wlien this was the case, reduction took place in a 

 much slighter degree, or not at all ; sometimes, and I observed 

 * Philosophical Transactions, 1843, p. 112. 



