Page:On Electromotive Wave accompanying Mechanical Disturbance in Metals in Contact with Electrolyte.djvu/11

Fig. 5.—Successive modifications of the "straight wire" ending in "cell form." (b) shows how the ends of A and B of the wire may be vibrated by ebonite clip-holders, H and H′. When A is excited, current of response in the wire, normally speaking, is from the unexcited B to the excited A. The stimulated wire becomes zincoid. Note that though the current of response is constant in direction, the galvanometer deflection in (d) will be opposite in direction to (b). In (e) is shown one of the two graduated circles by which the amplitude of vibration is measured.

the internal resistance of the cell and the variation of that resistance by the addition of chemical reagents being thereby rendered quite negligible. Ordinarily I use tap-water as the electrolyte. The responses obtained with tap-water are practically the same as those obtained with distilled water. Zinc wires in ZnSO₄ solution give responses similar in character to those given by, for example, Pt or Sn in water.

Character and Intensity of Response dependent on Molecular Condition.

The following experiments show how intimately the response phenomena is connected with the molecular condition of the acted wire:—

Effect of Annealing.—The following photographic record, fig. 6, shows the equal and opposite responses in A and B wires to a succession of uniform stimuli. Hot water was now substituted for the cold water (too high a temperature temporarily reduces the response); the cell