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



Effect of Annealing. — I repeated the experiment with the same wire, 

 after pouring hot water and allowing it to cool to the old temperature. 

 It will be seen from the cyclic curve (fig. 10, B), (1) that the sensitive- 

 ness has become very much enhanced; (2) that there is relatively less 

 divergence between the forward and return curves. Even this diver- 

 gence practically disappeared at the third cycle, when the forward and 

 backward curves coincided (fig. 10, C). The above results show in what 























/ 































4or 



60" 



60" 



100 



Fig. 10. — Cyclic curves for maximum effects due to increasing and decreasing 

 amplitude of -vibration. A, fresli wire; B, after annealing; C, the same after 

 three cycles. Abscissa represents the amplitude of vibration; the ordinate 

 represents the corresponding electromotive variation. 



manner the excitability of the wire is enhanced by purely physical 

 means. 



It is very curious to notice that the substitution of NaoC0 3 solution 

 as electrolyte produces results very similar to that produced by 

 annealing ; that is to say, not only is there a great enhancement of 

 sensitiveness, but there is also a reduction of hysteresis. Another 

 curious point is that, whereas with ordinary fresh wire the addition of 

 Na 2 C0 3 greatly enhances the sensitiveness, after the wire has been 

 annealed there is comparatively little further increase of sensitiveness 

 due to the addition of the reagent. 



