1176 The Galvanic Battery. [No. 108. 



one- twentieth of a minute, than any man would willingly allow to pass 

 through his body at once. The loss with ordinary zinc appears to 

 arise from portions of copper, lead, cadmium, and other metals being 

 set free on its surface by the action of the dilute acid, and these being 

 in contact with the zinc, form small, but very active Voltaic circles, 

 which cause great destruction of the zinc, and in the same proportion 

 as they serve to discharge or convey the electricity back to the zinc, do 

 they diminish its power of producing an electric current, which shall 

 extend to a greater distance across the acid, and be discharged only 

 through the copper or platinum plate which is associated with it, for 

 the purpose of forming a Voltaic apparatus. 



These evils are remedied entirely by adopting that process of amalga- 

 mation of the zinc described in a former section of this paper, by which 

 its surface is brought into one uniform condition, and those differences 

 of character between one spot and another, which are essential to the 

 formation of the minute Voltaic circles, above alluded to, effectually 

 prevented. Hence the full equivalent of electricity is obtained for the 

 zinc oxidised, and a Battery so constructed is only active while the 

 poles, or, as Faraday calls them, the electrodes, are in connection, ceas- 

 ing to act, or be acted on, the moment this connection is broken. The 

 superiority of the amalgamated zinc is farther due to the state of the solu- 

 tion in contact with it, for as the unprepared zinc acts directly and 

 alone upon the fluid, which the amalgamated does not, the former by 

 the oxide it produces quickly neutralises the acid in contact with its 

 surface, so that the progress of oxidation is retarded, whilst at the sur- 

 face of the amalgamated zinc, any oxide formed is rapidly removed by 

 the free acid present, and the clean metallic surface is always ready to 

 act with full energy on the water. 



When an amalgamated zinc plate is immersed in dilute sulphuric 

 acid, the force of chemical affinity exerted between the metal and the 

 fluid, is not sufficiently powerful to cause sensible action at the surfaces 

 of contact, and occasion the decomposition of water by the oxidation 

 of the metal, but it is sufficiently powerful to produce such a condition 

 of the electricity (or the power upon which chemical affinity depends,) 

 as would produce a current, if there were a path open for it. Now 

 the presence of a piece of copper touching both the zinc and the fluid 

 opens such a path, and its direct communication with the zinc is far 



