362 MR. RITCHIE'S EXAMINATION OF THE ELECTRIC 



air of the atmosphere acting as a chemical agent and an imperfect conductor. 

 The same fact is proved by the electric column of DeLuc. The plate of zinc 

 becomes partially oxidized by the oxygen of the atmosphere, electricity is ge- 

 nerated or set at liberty, and the film of moist air in contact with the two 

 metals acts as the fluid conductor in an ordinary voltaic arrangement. If the 

 compound plate be coated with electric cement to exclude the chemical action 

 of the air on the zinc, I will venture to predict that no decided electric effect 

 will take place. Until the supporters of the electric theory show by direct ex- 

 periment that electric effect does take place with this modification of the ap- 

 paratus, we must view the whole of their reasoning as founded on a gratuitous 

 supposition. Having thus shown that Volta and his followers have overlooked 

 what appears to me to be the very cause of the disturbance of electric equi- 

 librium in the two metals, I shall now demonsti'ate that the other principle 

 on which the theory is built is equally unfounded. This will appear obvious 

 from the two following experiments. 



Experiment I. 



Having poured into a watch glass a quantity of diluted sulphuric acid, I 

 placed on the surface of the fluid a piece of gold leaf, which was connected 

 with one of the cups of a delicate galvanometer. I then placed a disc of platina 

 foil in the fluid below the gold leaf, and connected it with the other cup of the 

 instrument ; scarcely any electro-magnetic efffect was produced. Having re- 

 moved the acid, I substituted water containing condensed chlorine : a very de- 

 cided electro-magnetic effect was produced. A similar effect was produced by 

 using nitro-muriatic acid, or aqua regia as it was formerly called, instead of 

 the chlorine. The needle of the galvanometer in both cases turned round in 

 the same direction as it does when zinc was substituted for the gold leaf and 

 copper for the platina. Having tried, by the common method, the conducting 

 powers of the diluted sulphuric acid and the water containing chlorine, I found 

 that the diluted acid was the most powerful conductor. When the preceding 

 experiment was repeated with discs of zinc and copper instead of discs of gold 

 and platina, I found that the most powerful effect was produced when the 

 diluted sulphuric acid was used. This experiment clearly proves that the 

 interposed fluid does not act merely as a conductor to the electricity excited by 



