CH. XII.] 



NON-POLARISABLE ELECTRODES. 



143 



end, or the middle of the same muscle, is connected by another 

 non-polarisable electrode in the same way to the other side of the 



Fig. 164. Diagram of Du Bois Reymond's non-polarisable electrodes, a, glass tube filled 

 with a saturated solution of zinc sulphate, in the end, c, of which is china clay drain n 

 out to a point; the clay is moistened with O'6 NaCl solution ; in the solution a well 

 amalgamated zinc rod is immersed and connected, by means of the wire A, with the 

 galvanometer. The remainder of the apparatus is simply for convenience of applica- 

 tion. The muscle and the end of the second electrode are to the right of the figure. 



galvanometer. If there is any electrical difference of potential 

 (that is, difference in amount of positive or negative electricity) 

 between the two parts of the muscle thus led off, there will be a 



Fig. 165. Arrangement for measuring the electromotive force of muscle. 

 (M'Kendrick.) 



swing of the galvanometer needle ; the galvanometer detects the 

 existence and direction of any current that occurs. 



Fig. 164 shows a more convenient form of non-polarisable 

 electrodes. 



