Page:On Electromotive Wave accompanying Mechanical Disturbance in Metals in Contact with Electrolyte.djvu/12

was then allowed to cool to its old temperature, when a second series of responses were taken, the stimulus intensity being the same as before. It will be seen how the responses are enhanced by annealing.

Fig. 6.—Series of responses, to uniform stimuli, of both A and B wires, before and after annealing.

Effect of Previous Vibration—The increased sensitiveness conferred by previous vibration has already been referred to before. I give below a record (fig. 7) obtained with platinum (I have obtained similar

Fig. 7.—Photographic record showing the effect of continuous stimulation in enhancing response (Pt). Each curve shows response (followed by recovery), the stimulus being kept constant throughout. The series of responses (a), enhanced to series (c) after continuous vibration (b).

records with other metals), which clearly shows how the response is enhanced after preliminary vibration.

Sometimes the wire gets into a very sluggish condition, when the response almost disappears; in other words, owing to some molecular modification, responsiveness is reduced from the normal positive value (by positive is meant that the acted wire becomes zinc-like or is zincoid) to zero. In these cases annealing or preliminary vibration are usually effective in transforming the sensitiveness from zero to a positive value.