^9^ Additional Notes, 



and equal shocks -, but tliat those made of larger plates are con- 

 siderably more powerful in fusing metals. 



Dr. Bostock's TJieory of Galvanism. 



John Bostork, M. D, of Liverpool, has offered the follow^ 

 iug Gahanic theory : — He thinks that the phenomena of the pile 

 of Volta may be all easiJy explained by admitting the truth of the 

 following po&iulatts. 



1 . I'h.at the electric fluid is always generated or liberated when 

 a metal, or any oxydable substance, is united to oxygen. 



2. Ihat the electric fluid has a strong attraction for hydro- 

 gen. 



3. That when the electric fluid, in passing along a chain of 

 conductors, leaves an oxydable substance to be conveyed through 

 water, it unites itself to hydrogen, from which it is again disen- 

 gaged, when it returns to the oxydable conductor. -^ 



The first of these propositions Dr. Bostock considers as almost 

 proved by the experiments of Fabroni, Davy, and Wollaston. The 

 second and third have not been directly established by experiment, 

 but are viewed by Dr. Bostock as highly probable. 



Dr. Bostock accounts for the operations carried on at the end of 

 the \\irc, in tlie interrupted circuit, as discovered by Nicholson, 

 in the fi)llowing manner. 



As the current of the electric fluid appears to pass from the 

 zinc, or plus end of the apparatus, to tlie silver end, it is flrst pro- 

 per to ascertain the action which takes place at the zinc end of the 

 wire. This appears to be the disengagement of oxygen in a con- 

 centrated state, by which the wire itself, Miien oxydable, is cor- 

 roded 5 but which, when the wire is formed of a perfect metal, is 

 disengaged in the form of oxygen gas. This oxygen appears to be 

 derived from the derompositicm of the water in which the wire 

 terminates, in consequence of the attraction which the electric 

 fluid possesses for hydrogen, and its incapacity of passing through 

 M'ater without being united to this substance, according to the 

 second and third postulates. The electric fluid, thus united to hy- 

 drogen, is carried to the other point of the wire, where, upon en- 

 tering the oxydable conductor, it is disengaged in the form of hy- 

 drogen gas, if water be the medium of communication. If a so- 

 lution of metallic oxyd be employed, it unites with the oxyd, and 

 reduces it. The decern [position of water is, therefore, elTccted at 

 the zinc point ajone, though the different gases which com])ose it 

 are discng.;j^vd at each of the points : and the process will continue 



