194 Mv. H. F. Baxter on the Force evolved 



solution was positive to the stronger. We were enabled in this 

 instance, as with the acid solution, to obtain a solution of such 

 strength as to give a constant current in a certain direction, and 

 then make the current due from muscular contraction overpower 

 this current. As we consider this fact of some importance, it 

 will be necessary to state the mode of ascertaining this constant 

 current. If we find, either upon the introduction of the fingers 

 of both hands at the same time, or upon the introduction of the 

 fingers of one hand, that a currcut existed in one direction to 

 the amount of about 2°, the current occurring during muscular 

 contraction, if it coincided with this constant current, would 

 cause the needle to advance to 4° or 5° or more ; but if it has 

 to overcome this constant current, the needle would only move 

 2° or 3°. We need scarcely add, that the needle of the galva- 

 nometer should continue to indicate this current whilst the 

 fingers remain in the solution, which may be indicated by the 

 needle receding to its normal position upon the withdrawal of 

 the fingers. A great difficulty is frequently experienced in ob- 

 taining this constant current. 



Several other experiments might be related in which the elec- 

 trodes were made to difi'er 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 we have related, the effect being- 

 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 inde- 

 cisive. The hot solution was not always positive to the cold 

 solution. We could always obtain the effect during muscular 

 contraction. 



We agree with Du Bois-Reymond as to the importance of 

 attending to the five circumstances to which he refers, and which 

 we have already alluded to. The circumstances that appear to 

 us to be the most infiuential in masking the ultimate result, are, 

 — 1st, the action of the fluid upon the surface of the electrodes ; 

 and2ndly,the reaction of the cutaneous secretions upon the fluids. 

 Although we cannot remove these sources of error, we have it 

 nevertheless in our power to counteract their effects by showing 

 that the current consequent \ipon muscular contraction can be 



