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