ABC 



with the galvanometer. There is a large deflection to your 

 right, indicating current in the skin from C to A, i.e., that A has 

 been rendered electro-negative to C, an unaltered point, and to 

 other unaltered points inclusive of B, which by the previous 

 trial you saw to be unaltered. We infer from this first pair of 

 trials that the outgoing (unequivocal) blaze B A depends upon 

 post-kathodic " pull " under A at or near the outer surface. 



Now reverse the direction of excitation, passing the induction 

 shock through the skin in the negative direction from A 

 to B. 



First test the altered state of B, in the same way as before 

 (balance B with C, excite through A B, connect B C with the 

 galvanometer), there is no effect. Then test the altered state of 

 A (balance A C, excite A B, connect A C), there is a large deflec- 

 tion to your right, i.e., current in the skin from C to A, i.e., A is 

 electro-negative to unaltered points C and B, etc. We infer 

 from this second pair of trials, that the outgoing (equivocal) 

 blaze B A depends upon post-anodic " pull " under A at or near 

 the external surface. And from both pairs of trials we infer the 

 simple conclusion that the blaze-currents B A unequivocal by 

 excitation B A and equivocal by excitation A B depend upon 

 an electro-motive action aroused at or near the external surface. 

 We must further infer, against all our preconceptions of the 

 matter, that this electro-motive action is aroused by the kathode 

 as well as by the anode of an exciting current (i.e., is post- 

 kathodic as well as post-anodic) and that in both cases it 

 consists in an electro-negative state of the active part, i.e., that 

 this part is galvanometri- 

 cally positive to inactive 

 parts the seat of an in- 

 creased anionic solution- 

 pressure. 



44. Intact external 

 surface. We shall find in 

 this ABC plan a ready means of testing an intact external 

 surface, and of thereby learning what are the separate contri- 

 butions of A and of B in any total reaction between A and B ; 



