Fluid Galvanic Battery. 263 



I subsequently tried the effect of sulphuric acid mixed with a 

 solution of common salt, of dilute sulphuric and muriatic acid 

 together, of undiluted muriatic acid, and muriatic acid diluted 

 with a small quantity of water, and found by the galvanometer 

 that a galvanic current of the same power was produced by the 

 Bame cast-iron cell and zinc plate, whether they were excited by 

 one part of the sulphuric acid which I first used, diluted with 

 two of water, or with one part of the strongest sulphuric acid 

 diluted with three of water, or with the first sulphuric acid mixed 

 with three times its bulk of a strong solution of common salt, or 

 with the strongest acid mixed with 3| times its bulk of the 

 same solution, or with sulphuric and muriatic acid together 

 diluted with a volume of water about twice as great as that of 

 the sulphuric acid, or with undiluted muriatic acid, or muriatic 

 acid diluted with a small quantity of water. Cast iron and zinc 

 appear to be equally excited by the seven fluids just described. 



Seeing, by the indications of the galvanometer, that the gal- 

 vanic current produced by a cast-iron cell excited by any of the 

 preceding fluids was exceedingly powerful, I resolved to compare 

 it with tbe current produced by a nitric acid cell of the same 

 size, and found that nearly the same deflection of the needle was 

 produced by the two currents. I used a cell of tbe cast-iron 

 nitric acid battery rather than one of Grove's or Bunsen's, because 

 I found it more convenient than either, and not inferior in 

 power. 



The two cast-iron cells which I used were of the same size and 

 shape; both were of a rectangular form. They were made for 

 holding porous cells which contained zinc plates 4 inches square ; 

 their inside width was about |ths of an inch. For the nitric 

 acid battery their width could not be less : were it less, the 

 porous cells would not fit in the iron cells. The thickness of 

 the zinc plate was about £th of an inch. Therefore the distance 

 between each side of the zinc and cast iron was f ths of an inch. 

 This distance cannot be diminished in tbe cells of the nitric acid 

 battery; but in the battery excited with any of the above- 

 mentioned fluids, it may be diminished without limit, and thus 

 the galvanic power of the battery may be greatly increased. 



When the distance between the zinc and cast iron of a cell 

 excited by one part of sulphuric acid and two of water, or by 

 any of the fluids which have been described, does not exceed the 

 vsth of an inch, the voltaic power of the cell is considerably 

 superior to that of a cell of equal size of the nitric acid battery. 

 1 prepared a 4-inch cell and zinc plate of the nitric acid bat- 

 tery, and a zinc plate and cast-iron cell of the same size, in which 

 the distance between the zinc and cast iron was about the y^th 

 of an inch. The opposite ends of these two cells were connected 



