Page:On Electromotive Wave accompanying Mechanical Disturbance in Metals in Contact with Electrolyte.djvu/21

1902.] on carefully applying just the proper amount, I find that the stimulus evokes a responsive electric variation which is less than the normal, and the period of recovery is very much prolonged from the normal 1 minute before to 5 minutes after the application of the reagent (fig. 13(a)). In the next record (fig. 13(b)) the arrest is more pronounced, i.e., there is now no recovery. Note also that the maximum is attained much later. Stimuli applied after the arrest produce no effect, as if the molecular mechanism became locked up.

Résumé.

 Molecular disturbance produced by mechanical stimulus gives rise to an electrical disturbance. In the majority of cases, under normal conditions, the responsive electrical current in a wire is from the less to the more disturbed. Response may be obtained by (1) method of block, (2) by methods of negative or positive variation. The electromotive variation disappears on the cessation of disturbance. The intensity of the electrical variation produced by a given disturbance is modiﬁed by the molecular condition of the wire. Annealing, or previous continued vibration, enhances the electric effect. The abnormal response due to molecular modiﬁcation is transformed into normal by continued vibration. The intensity of electromotive variation is increased with increasing intensity of stimulation. In a curve—the ordinates representing the electrical effects, and the abscissm the amplitudes of vibration-«the ﬁrst part is slightly convex to the abscissa, the second is approximately straight, and the third concave. With increasing stimulation there is a tendency for the electrical variation to reach a limit. <li>A maximum electrical effect is produced by continuous vibration, which is deﬁnite for a given amplitude of vibration. A curve showing the relation between the maximum effect and the amplitude of vibration exhibits the same characteristics as in the last case.</li> <li>Hysteresis is exhibited in cyclic curves. The forward and return curves tend to coincide after several cycles. Previous annealing reduces hysteresis, and after one or two cycles the wire assumes a constant condition of sensibility.</li> <li>Chemical reagents may profoundly modify the electric excitability. Some increase the excitability. Others depress or even abolish the excitability. The after-effects are sometimes very persistent.</li> <li>The effect of weak solution is sometimes the opposite to that of strong solution.</li> </ol>