120 ANNUAL OF SCIENTIFIC DISCOVERY. 



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be expected to exhibit thermic effects. (This Mr. Grove has been 

 enabled to effect in a sensible degree.) 



The effect of electricity in the disruptive discharge, as in the voltaic 

 arc and the electric spark, would seem at first sight to offer greater 

 difficulties of explanation on the dynamic theory. The brilliant phe- 

 nomenal effects of the electric discharge, and the apparent absence of 

 change in the matter affected by it, would at first lead the observer to 

 believe that electricity was a specific entity. With ordinary flame, or 

 the apparent effects of combustion, however, the idea has to a great 

 extent been abandoned that such visual effects are due to specific mat- 

 ter, and it is regarded by many as an intense motion of the particles 

 of the burning body. So with electricity. If in regard to the disrup- 

 tive discharge it can be shown that the matter of the terminals, or of 

 the intervening medium is changed, the necessity for the assumption 

 of a fluid or ether ceases, and to say the least, a possibility of viewing 

 electricity as a motion or affection of ordinary matter is opened. To 

 make evident the relation of the electrical discharge to combustion, 

 and the fact that the terminals were themselves affected, the voltaic 

 arc was taken first between silver, and then between iron terminals ; 

 in the first case a brilliant green-colored flame was produced, and in 

 the second a redish scintillation, as in the ordinary combustion of the 

 metals. The known transport of particles of the terminals from one 

 pole to the other, and the different effects of different intervening 

 media on induction, are instances of the, train of molecular changes 

 consequent upon electrical action. 



Hitherto the polarity of the gaseous medium existing between the 

 metallic or conducting terminals of the electrical circuit was only 

 known as a physical polarity and not shown to have an analogous 

 chemical character with that existing in electrolytes anterior to elec- 

 trolysis ; but Mr. Grove stated, that he had recently shown, that 

 mixture of gases having opposite electrical, or chemical relations, such 

 as oxygen and hydrogen, or compound gases such as carbonic oxide, 

 were electro-chemically polarized, or had their electro-negative, or 

 electro-positive elements thrown in opposite directions ; thus, if a 

 silvered plate be made positive in such gases it is oxidized ; if negative, 

 the dark spot of oxide is reduced. Here, as in other experiments, was 

 an effect on the terminals, and an effect of polarization of the inter- 

 medium. In the experiments hitherto referred to, solid terminals had 

 been used ; it became important to examine what would be the effect 

 of liquid terminals, for instance, water : the spark, or disruptive dis- 

 charge of electricity was readily obtained from its surface, but hitherto 

 no voltaic battery had been found to show a discharge at any sensible 

 distance from the surface of water. A nitric acid battery consisting 

 of 500 cells had been constructed by Mr. Gassiot, which as regards 

 intensity of action was probably the most powerful ever constructed. 

 With this Mr. Grove was able to shew an experiment which he had 

 first made when experimenting with Mr. Gassiot some time ago, and 

 which produced the effect he had long sought for, viz., a quantitative 

 or voltaic discharge at a sensible distance from the surface of water. 



