4i8 EXPERIMENTAL INVESTIGATIONS. 



and when the glass is, so to speak, coated by the elements, 

 decomposition would cease. 



The quantity of gas in the above experiment was too small 

 for analysis ; and in all probability, could it have been 

 examined, some mixed gas would have been found to have 

 been eliminated from each electrode. When, however, there 

 is a small interruption in the secondary circuit of RuhmkorfFs 

 coil, producing a rapid succession of sparks, I have found that 

 between electrodes in the same circuit true polar decompo- 

 sition takes place, and a galvanometer is steadily deflected 

 according to the direction of the current, while without such 

 interruption the movements of its needle are most irregular. 

 I therefore repeated the experiment of interposed glass with 

 an interruption in the circuit, and found that electrolysis took 

 place apparently as before ; and in this case there was pro- 

 bably true polar decomposition. 



Although I failed with thirty cells of the nitric acid bat- 

 tery, I should expect that a battery of very high intensity, 

 such as the 500 cells nitric acid, or the water-battery of Mr. 

 Gassiot, would produce effects of electrolysis across glass 

 without the use of the coil. 



AN EXPERIMENT IN MAGNETO-ELECTRIC 

 INDUCTION. 



Philosophical Magazine, March 1868. 



SHORTLY after the publication of Mr. Wilde's experiments on 

 magneto-electric induction, it occurred to me that some of the 

 ordinary effects of the Ruhmkorff coil might be produced by 

 applying to it a magneto-electric machine. I tried an ordi- 

 nary medical machine with a small coil, made by Mr. Apps, of 

 3^ inches length by 2 inches diameter, and having about f of 

 a mile of fine secondary wire. 



The result was very unexpected. The terminals of the 

 magneto-electric coils being connected with the primary coil 

 of the Ruhmkorff, and the contact-breaker being kept closed, 



