276 



Prof. J. C. Bose. On Electromotive Wave [May 21. 



position, alternate equal stimulations of A and B produce equal and 

 opposite electromotive effects, and when the two ends are stimulated 

 simultaneously there is no resultant effect. 



Increased Excitability produced by Preliminary Vibration. — If now one- 

 half of the wire, say the A half, be vibrated for a time, the electric 

 excitability of that half will be found to be more or less permanently 

 augmented, presumably by increased molecular mobility conferred by 

 vibration. The response of A would now be found to be very much 

 enhanced, as compared with its previous response, the response of 

 B remaining the same as before. If now both the ends are simul- 

 taneously vibrated, the balance which previously existed will be 

 found to be disturbed, the resultant showing that A has been rendered 

 the more excitable. 



If B be now vibrated for a time, the former approximate balance will 

 be re-established by the enhanced responsiveness of B. Thus in the 

 following experiment with the clamp at the approximate balancing 

 point — 



After the end A has been 



After the end B has been 

 vibrated for an equal 



E expense of A. 



Eesponse of B. 



Resultant 

 response. 



+ 5 divisions 

 + 10-5 „ 



+ 10-5 „ 



— 4 - 5 divisions 

 -45 



-95 „ 



-f0"5 divisions 

 + 60 „ 



+ io 



Effect of Chemical Reagents. — It will be shown that keeping the 

 electrolyte by which contact is made constant, the electric excitability 

 of the wire depends on the molecular condition of the wire. Certain 

 electrolytes, such as dilute solution of NaCl, dilute solution of bichro- 

 mate of potash, &c, are normal in their action, that is to say, with 

 such contacts the response to stimulation is practically the same as 

 with distilled water contact. 



Contact made with dilute NaCl solution may therefore be regarded 

 as the normal contact. There are again certain chemical reagents 

 which enhance the electrical excitability ; others on the contrary 

 produce great depression, or abolition of excitability. 



Electric Comparator. 



We may compare the relative electric excitability conferred by 

 chemical reagents by the method of balance. Having previously 

 obtained a balance (with water or dilute NaCl solution contacts 



