Laios of the Elementary Voltaic Battery. 47 



feet, the needle being retained at zero by a light trigger placed 

 against the index. The immersion being then made as instantane- 

 ously as posible, the observer stationed at the needle marked wheth- 

 er the index receded from its lateral support, this of course indicating 

 that the deflecting force was more than a balance for the torsion. 

 In this case the number of degrees of torsion read off the upper circle 

 was recorded -j- (Plus). If no movement of the needle occurred, the 

 number was recorded — (Minus). Experiments were thus succes- 

 sively made, always setting the torsion key previous to immersion at 

 some number either less or greater than the former number accord- 

 ing as this had been found plus or minus. In this way after repeat- 

 ed observations, a close approximation to the momentary effect was 

 procured. 



Having observed that the momentary effect was influenced to some 

 extent both by the period of exposure to the liquid and by the inter- 

 val of repose between the immersions, two distinct sets of experi- 

 ments were made, in order as far as possible to separate these two 

 influences. In the first set, the intervals of repose in the air were 

 varied, as follows, — 1 min. for 1st result, 2 min. for 2nd, 4 min. 

 for 3d. The period of exposure to the solution was constant, name- 

 ly, minute after each dip. 



In the second set, the periods of exposure to the solution were 1 

 min., 2 min., 4 min., 8 min., and the interval of repose out of the 

 solution was constant. In each observation besides the momentary 

 action, the permanent deflection was noticed. 



1st set. — Period of exposure to solution 1 min. in all the observa- 

 tions. — Interval of repose 1 min. 

 1st. obs. momentary def. —360° 

 2nd. " " 



3rd. « " 



4th. " " 



5th. " " 



320+340 

 Result, 2 = 330 of mom. def. and between 103 and 104 



perm. def. 



Interval of repose, 2 minutes. 

 1st. obs. momentary def. +340° Perm. def. 104° 



2nd. " " " +360 " " 104 



3rd. " « " +380 " " 103 



4th. " " " -400 " " 103 



380+400 

 Result, a =390 of mom. def. and as before of perm. def. 



