116 ELECTBIC FORCE CHAP. X. §.I. 



The solution in one vessel was now diluted to 

 one-half. Upon the first introduction of the fingers, 

 the strong solution was positive 5°. Keeping the 

 fingers in and waiting imtil the needle had become 

 motionless, the contracted arm was positive to the 

 other ; if the arm connected with the strong solution 

 was contracted, the effect was greater than when the 

 other was contracted, the current in the former case 

 rising to 5°, in the latter to 3° or 3°. 



With the acid solution. Upon the first introduction 

 of the fingers, the needle would sometimes go 30° 

 or 40°, but generally speaking it would oscillate first 

 to one side and then to the other. Withdrawing the 

 fingers of one hand and then reintroducing them, 

 this hand was positive to the other. Keeping the 

 fingers quiescent, and contracting the muscles of the 

 arm, the corresponding fingers were positive 4°. 



The solution in one vessel was diluted to half the 

 strength of the former ; the strong solution was 

 positive to the other upon the introduction of the 

 fingers. If the difference between the two solutions 

 was not too great, (the exact strength being difficult 

 to state,) I could determine a slight current to pass 

 in a constant direction, and then make the current 

 arising during muscular contraction overcome this 

 constant current. Strong solutions were foimd best 

 for this purpose, firom their forming, perhaps, a 

 better conducting liquid than the weaker solutions. 



With the alkaline solution. Upon the first intro- 

 duction of the fingers no definite result, the needle 



