ELECTROLYSIS ACROSS GLASS. 4*7 



detect no signs of electrolysis, when instead of the Ruhmkorff 

 coil a nitric acid battery of thirty cells was employed. 



In the first experiment the evolution of gas gradually 

 diminished, and ceased after about twenty minutes' experi- 

 ment ; but upon intercepting communication with the battery 

 for ten minutes, and then re-connecting it, the evolution took 

 place again ; or a recurrence of electrolysis could be produced 

 by reversing the direction of the current. 



When the flask, after twenty minutes' experiment, was 

 removed from the outer vessel and tapped, minute bubbles 

 rose from the interior surface. When a tolerably thick test- 

 tube was used instead of the Florence flask, a very slight effect 

 of electrolysis could be detected ; and when the outer wire 

 was removed to a short distance from the surface, sparks 

 passed, but not of half the length of those with the Florence 

 flask. When, however, a large phial of somewhat greater 

 contents than the Florence flask was used, the effects were 

 the same as with the latter, showing, as I expected, that 

 surface is an important element in the success of the expe- 

 riment. 



There seems little doubt from the above experiments that 

 the electrolysis was effected by induction across the thin glass 

 of the Florence flask ; and its cessation after a time and recur- 

 rence after interruption of the current would seem to indicate 

 something like a state of charge or of polarisation of the sur- 

 face of the glass. 



Whether the bubbles which arose from the interior surface 

 of the glass were the effect of electrolytic action or mere air- 

 bubbles, cannot be affirmed with certainty ; but as there was 

 distinct evolution from the platinum wires, the corresponding 

 elements must have been either dissolved, evolved, or depo- 

 sited somewhere, and the most probable place of evolution 

 would be the surface of the glass. If this be so, the glass 

 would act in effect just as an interposed plate*of inoxidable 

 metal, though the one acts by induction, the other by con- 

 duction. 



The oxygen and hydrogen may, however, be spread over 

 the surface of the glass without evolution in the form of gas ; 



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