264 The Rev. Prof. Callaii on a New Single 



with the opposite cuds of the coil of the galvanometer, in such a 

 way, that, as soon as the two cells should be filled, the galvanic 

 currents from them would flow simultaneously through the coil 

 in opposite directions. The cell of the nitric acid battery was 

 first filled : it was in the best working order, and produced a 

 steady deflection of 8.2°. The other cell was then filled with one 

 part of sulphuric acid and two of water, and the voltaic currents 

 from the two cells flowed simultaneously through the coil in 

 opposite directions. The current from the cell excited by dilute 

 sulphuric acid destroyed the entire deflection produced by the 

 nitric acid cell, and produced an opposite and steady deflection 

 of 72°. On another occasion I made a similar experiment with 

 a nitric acid cell and one of the same size, in which the distance 

 . between the zinc and cast iron was about the j\jth of an inch, 

 and which was excited with one of the fluids already described. 

 In this experiment the sine galvanometer was used, and the 

 compass-box containing the magnetic needle was slid 21 1 

 inches from the centre of the coil in the direction of its axis. 

 The voltaic current was first sent through the coil from the nitric 

 acid cell, and a deviation of 38° was produced. The single fluid cell 

 was then filled, and the galvanic currents flowed simultaneously 

 from the two cells in opposite directions through the coil. The 

 current from the single fluid cell destroyed the entire deviation 

 of 38°, and produced a deviation of 42° on the opposite side of 

 the magnetic meridian, thus showing that its power was more 

 than twice as great as that of the current produced by the nitric 

 acid cell. The porous cell employed in this experiment was of 

 the best quality ; it was perfectly saturated on the outside with 

 nitro-sulphuric acid, and on the inside with dilute sulphuric acid, 

 consisting of one part of very strong and pure sulphuric acid 

 and five of water. 



From the experiments and results which have been described, 

 it is evident that a single fluid battery more powerful than any 

 nitric acid battery of the same size, may be made by exciting 

 a suitable arrangement of cast-iron cells or plates and amalga- 

 mated zinc with any of the following fluids. First, undiluted 

 muriatic acid, or muriatic acid diluted with a small quantity of 

 water; secondly, muriatic and sulphuric acid together diluted 

 with a quantity of water a little more than twice as great by 

 measure as that of the sulphuric acid; thirdly, sulphuric acid 

 diluted with about twice its bulk of water, or the strongest sul- 

 phuric acid made from sulphur diluted with three times its bulk 

 of water ; fourthly, sulphuric acid mixed with three times its 

 bulk of a strong solution of common salt, or the strongest sul- 

 phuric acid made from sulphur mixed with about 3| times 

 its bulk of the same solution. The solution may be made 



