340 Dr. Faraday's Experimental Researches in Electricity, 



posed to occasion over the whole of its surface ; but this is not 

 the case. When the electric currents of two pairs of platina 

 and zinc plates were opposed, the difference being that one 

 of the zincs was amalgamated and the other not, the current 

 from the amalgamated zinc was most powerful, although no 

 gas was evolved against it, and much was evolved at the sur- 

 face of the unamalgamated metal. Again, as Davy has shown*, 

 if amalgamated and unamalgamated zinc be put in contact, 

 and dipped into dilute sulphuric acid, or other exciting fluids, 

 the former is positive to the latter, i. e. the current passes 

 from the amalgamated zinc, through the fluid, to the unpre- 

 pared zinc. This he accounts for by supposing that " there 

 is not any inherent and specific property in each metal which 

 gives it the electrical character, but that it depends upon its 

 peculiar state — on that form of aggregation which fits it for 

 chemical chancre." 



1005 The superiority of the amalgamated zinc is not, how- 

 ever, due to any such cause, but is a very simple consecjuence 

 of the state of the fluid in contact with it; for as the unpre- 

 pared zinc acts directly and alone upon the fluid, whilst that 

 which is amalgamated does not, the former (by the oxide it 

 produces) quickly neutralizes the acid in contact with its sur- 

 face, so that the progress of oxidation is retarded, whilst, at 

 the surface of the amalgamated zinc, any oxide formed is in- 

 stantly removed by the free acid present, and the clean me- 

 tallic surface is always ready to act with full energy upon the 

 water. Hence its superiority (1037.). 



100(5. The progress of improvement in the voltaic battery 

 and its applications, is evidently in the contrary direction at 

 present to what it was a few years ago ; for in place of in- 

 creasing the number of plates, the strength of acid, and the 

 extent altogether of the instrument, the change is rather 

 towards its first state of simplicity, but with a far more inti- 

 mate knowledge and application of the principles which govern 

 its force and action. Effects of decomposition can now be 

 obtained with ten pairs of plates (4? 17.), which required five 

 hundred or a thousand pairs for their production in the first 

 instance. The capability of decomposing fused chlorides, 

 iodides, and other compounds, according to the law before 

 established (380. &c.), and the opportunity of collecting cer- 

 tain of the products, without any loss, by the use of apparatus 

 of the nature of those already described (789. 814. &c.), ren- 

 der it probable that the voltaic battery may become a useful 

 and even oeconomical manufacturing instrument; for theory 

 evidently indicates that an equivalent of a rare substance may 



* Philosophical Transactions, 1826, p. 405. [or Phil. Mag. and Annals, 

 N.S„ vol. i. p. 102.— Edit] 



