416 EXPERIMENTAL INVESTIGATIONS. 



communication around the edges, it is hardly necessary to 

 say that, according to received opinions and experiments, no 

 current passes and no electrical effects appear. I was led 

 by some theoretic considerations to thiiik that this rule might 

 not be without an exception, and the following experiment 

 realised my views : 



A Florence flask, well cleaned and dried, was filled two- 

 thirds full of distilled water, with a few drops of sulphuric acid 

 added to it, and placed in an outer vessel containing similar 

 acidulated water, which reached to the same height as the 

 liquid in the interior. A platinum wire was passed through a 

 glass tube, one end of which was hermetically sealed to the 

 platinum, but so as to allow a small portion of the wire (about 

 ^th of an inch) to project ; the other end of the wire was 

 passed through a cork, and the cork fitted to the mouth of 

 the flask ; when the cork was introduced the projecting end 

 of the platinum wire was three-quarters of an inch below the 

 surface of the interior liquid ; a similar coated wire was dipped 

 into the outer liquid, and this and the wire which passed 

 through the cork were brought respectively into connection 

 with the extremities of the secondary coil of a Ruhmkorff 

 apparatus. Upon the latter being excited by the battery a 

 stream of minute bubbles arose from both the platinum 

 points, proving clearly that electrolysis took place, notwith- 

 standing the interposition of the glass. The portions of the 

 flask above the liquid, both outside and inside, were perfectly 

 dry, so that there could have been no communication of the 

 current over the surface of the glass. This was farther proved 

 by removing the outer wire a short distance from the surface 

 of the water, when sparks passed nearly equal in length to 

 those which took place between wires from the terminals. As 

 the outer wire was farther removed, keeping it near the glass, 

 the sparks passed along the surface of the latter for a short 

 distance ; and as it was farther removed they ceased, thus 

 showing conclusively that there was no passage of electricity 

 over the upper and unwetted surface of the glass. 



With distilled water unacidulated I could observe no effect 

 of electrolysis. 



With acidulated water and the same arrangement I could 



