118 ELECTEIO FORCE CHAP. X. §. I. 



great di£aculty, however, is frequently experienced in 

 obtaining this constant current. 



Several other experiments might be related in 

 which the electrodes were made to dififer in size, one 

 being narrow, the other broad; or where one was 

 made to dip deeper into the solution than the other. 

 The general results indicated that a difference in 

 extent between the surfaces of the platinum electrodes 

 and the solutions, occasioned an effect upon the 

 needle upon the first introduction of the fingers. 

 In other experiments larger vessels were employed, 

 so as to insert the whole of the hand and wrist; 

 the results coincided with those that have been 

 related, the effect however was greater. 



The solutions were made to vary as to temperature 

 by placing the glass in a vessel containing hot 

 water, and then carefully stirring the solution so as 

 to make it completely uniform. One vessel was at 

 the temperature 65° F. and the other 115°- The 

 results upon the first introduction of the fingers 

 were indecisive. The hot solution was not always 

 positive to the cold solution. The effect during 

 muscular contraction could always be obtained. 



I agree with Du Bois Eetmond as to the import- 

 ance of attending to the five circumstances to which 

 he refers, and which have been already alluded to. 

 The circumstances that appear to me to be the most 

 influential in masking the ultimate result are, 

 1st, the action of the fluid upon the surface of the 

 electrodes ; and, 2ndly, the reaction of the cutaneous 



