Contact Theory ofGalvanhm. 371 



fully acting fluids. The following experiments will probably 

 be more decisive with respect to the subject now before us. 



If I bring a fluid between homogeneous plates, a current 

 ought not to originate according to any theory, on connecting 

 the plates with the multiplier, from the independent action of 

 this system; or if 1 2 n/^r/)o<,f a fluid between homogeneous plates 

 in an active circuit, this interposition would, according to each 

 theory, influence the force of the circuit in no other manner 

 than by its opposing power as long as the plates are un- 

 changed^. It then appears : — 



a. That concentrated sulphuric acid inserted in an active 

 circuit between homogeneous zinc plates or muriatic acid 

 between homogeneous platinum plates, considerably weakens 

 the force of this circuit; a proof that a strong opposition to 

 the conduction has arisen in the circuit. 



h. That in like manner distilled water inserted in the cir- 

 cuit between homogeneous zinc plates or nitric acid between 

 homogeneous platinum plates considerably diminishes its 

 power. 



c. That, however, diluted sulphuric acid inserted in the cir- 

 cuit between homogeneous zinc plates, or a mixture of mu- 

 riatic and nitric acids between homogeneous platinum plates, 

 weaken the power but little in proportion ; a proof that from 

 the mixture (and that undoubtedly from the excited chemical 

 reaction) of the fluids the opposition to the conduction has 

 really diminished. The details of the experiments are as 

 follows. 



In the apparatus A a zinc and copper circuit K Z (of each 

 plate 1 1 '2 Parisian square inches immersed at 4 lines distance) 

 was connected in highly acidulated water with the multiplier 

 M (consisting of thick copper wire but not of many coils), and 

 the interposed intermediate apparatus which contained the 

 zinc plates a a, and either water or fuming sulphuric acid, or 

 diluted sulphuric acid, as the exciting fluid. The distance of 

 the plates a a was 14 lines, the immersed surface Tl square 

 inch. The measure of the power of the current was always 

 taken by the first oscillations of the needle, which was placed 



2 B 2 



