CHAP. X. §. I. DUEING MUSCULAR CONTEACTION. Ill 



any, but indecisive results. Upon repeating the 

 experiments on another occasion, some definite 

 result was ultimately obtained, and also a clue to 

 my former failures. I found that when the muscles 

 of the arms were contracted alternately at definite 

 periods, and continuing this act for some time, that 

 OS the hands became moist, a decided effect upon the 

 needle occurred, indicating the contracting arm to 

 be positive^ to the other. These results may be 

 considered as due partly to the reaction of the acid 

 secretions of the hand upon the metallic electrodes, 

 partly to the skin becoming a better conductor than 

 the dry cuticle, and partly perhaps to thermo-electric 

 action. 



The question now arose, could not the effect 

 which might be due to muscular contraction coincide 

 with that which arose from the action of the cutaneous 

 secretions ? From the results obtained by Du Bois 



^ Some difficulty is frequently experienced in comprehending 

 tie results obtained by different inquirers in reference to the 

 direction of the current ; it is uncertain to which of the circles 

 of the old construction, the simple or compound, reference is 

 made for illustration, or whether it be the positive metal or the 

 positive electrode that is referred to ; hence arises an apparent 

 contradiction The direction of the current is of the utmost 

 importance to he attended to in accounting iot the effects 

 produced. I always allude to the simple elementary circle for 

 illustration ; if zinc, platinum, and dilute acid, be formed into a 

 oirouit, the current goes, according to the usual mode of 

 expression, from the zinc to the platinum ; the platinum being 

 the positive electrode. In the combination of an acid with an 

 alkali, the electrode in contact with the add is the positive 

 electrode. 



