492 



10 grains of cyanide of mercury and 100 grains of hydrate of potash 

 dissolved in 2| ounces of aqueous hydrocyanic acid containing 5 per 

 cent, of anhydrous acid. 



The vibrations and sounds occur only at the surface of the negative 

 mercury electrode, as already described (Proc. Roy. Soc. No. 44, 

 page 177) ; and out of a large number of liquids examined, the only 

 ones in which phonetic vibrations occurred were solutions of alkaline 

 cyanides containing dissolved mercury ; and these only give the sounds 

 with electrodes (or at least a cathode) of mercury, not with solid 

 metals nor with fused alloys. 



The vibrations and sounds vary considerably according to the 

 size and number of the voltaic elements ; with a few elements of 

 large surface, the vibrations were small and the sounds high, and with 

 many elements of small surface they were much larger and the tone 

 lower. The most suitable number of elements to produce them is 

 either two of Grove's or five of Smee's. 



The interposition of a coil of stout copper wire in the circuit made 

 the vibrations wider and the sound more base ; and if an iron core was 

 suddenly thrust into the axis of the coil, they became still wider and 

 the sounds still more base, and remained so as long as the iron con- 

 tinued there ; but if a secondary coil containing a great length of 

 fine copper wire surrounded the primary coil (with or without an iron 

 core), and the ends of the secondary wire were suddenly united, the 

 vibrations instantly became narrower and the sounds more high, and 

 remained so as long as the secondary circuit was closed. 



The vibrations of the mercury and electrolyte make the electric 

 current which produces them sensibly intermittent, similar to the 

 influence of a vibrating coil-hammer ; and they may be used to some 

 extent in a similar way to that instrument to produce shocks, &c. 

 by means of a secondary coil. A strong electro-magnet placed in 

 various positions near the locality of the vibrations had no perceptible 

 influence upon them. 



The author considers the vibrations to be of electro-chemical origin, 

 and to result from an attraction between the mercury of the negative 

 electrode and the mercury of the electrolyte. He supposes that to 

 produce the vibrations, either the voltaic force itself must be of an 

 intermittent nature, or the resistance opposed to that force by the 

 liquids employed must be intermittent, and intends to make the 



