294 



M. De la Rive's Researches 



Exp. III. — Pairs the same as the preceding bid charged with 

 a solution still less acid. 



By employing pairs similar to the preceding, with the double 

 magnetic galvanometer, I found that two, twenty, and a hun- 

 dred and twenty pairs developed perfectly equal currents. 

 The strongest currents were developed by fourteen and seventy 

 pairs. 



To exhibit the influence of the duration of the effect upon 

 its intensity, I shall produce some further experiments per- 

 formed with pairs with surfaces only four inches square, but 

 charged with a strong solution of nitric acid. Two pairs gave 

 in the first instant 215° of Breguet's helix, at the end of five 

 minutes 100°, at the end of ten minutes 80°. In another 

 experiment four pairs gave in the first instant 300°, at the 

 end of five minutes 160°, at the end of fifteen minutes 100°. 

 Lastly, six pairs gave at the first instant 500°, but the effect 

 diminished with great rapidity. The preceding pairs had 

 never been employed; but after using them a certain number 



