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Mr. Grove on the Electro-chemical Polarity of Gases. 499 



In none of the above papers, and in no researches on electri- 

 city of which I am aware, is there any experimental evidence 

 that the polarization of the dielectric is or may be chemical in 

 its nature, that, assuming a dielectric to consist of two substances 

 having antagonist chemical relations, as for instance, oxygen and 

 hydrogen, the particles of the oxj'gen wou^ld be determined in 

 one direction, and those of the hydrogen in the other; the only 

 experimental result bearing on this point with which I am ac- 

 quainted, is the curious fact which was observed by Mr. Gassiot 

 and some other electricians who experimented with him in the 

 year 1838, viz. that when two wires forming the terminals of a 

 powerful battery were placed across each other, and the voltaic 

 arc taken between them, the extremity of the wire proceeding 

 from the positive end of the battery was rendered incandescent, 

 while the negative wire remained comparatively cool ; it was at . 

 that time believed that there was some effect exhibited here extra 

 the voltaic circuit. Shortly afterwards I showed that with all, 

 or at all events a great number of metals, the positive terminal 

 was more heated than the negative, and that the portion of the 

 crossed wire which was positive became more incandescent than 

 that of the negative, from the greater heating effect developed at 

 the positive point when the disruptive discharge took place. I 

 suggested as an explanation of this phsenomenon, the possibility 

 that in air, as in water, or other electrolyte, the oxygen or elec- 

 tro-negative element was determined to the positive terminal, 

 and that from the union of the metal with that oxygen a greater 

 heating effect was developed. This, with some other impres- 

 sions, 1 mentioned in a letter to my friend Dr. Schonbeiu, not 

 intended for publication, but which shortly afterwards found its 

 way into print*. 



Though by no means thinking tliat this explanation was in 

 every respect satisfactory, there were many arguments in its 

 favour ; and the fact strongly impressed my mind as evincing a 

 very striking difference in character between the effect of the 

 discharge at the positive and negative terminals, and as present- 

 ing, as far as it went, a distant analogy to the effect of elec- 

 trolysis. 



In the year 1848, while experimenting with Mr. Gassiot with 

 a nitric acid batteiy consisting of 500 well insulated cells, I made 

 the following experiment : — Two wires of platinum ^'^th of an 

 inch in diameter, forming the terminals of the battery, were 

 immci-sed in distilled water ; the negative wire was then gra- 

 dually withdrawn until it reached a point a quarter of an inch 

 distant from the surface of the water. A cone of blue flame was 

 now perceptible, the water forming its base, and the point of the 

 * Philosophical Magazine, 1840, vol. xvi, p. 478. 

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