Page:Collected Physical Papers.djvu/216

196 shown to exhibit remarkable similarities. Still more extraordinary are the similarities that exist even in abnormalities, several instances of which will be given later; of these I shall mention here only one. It

was shown in experiments with electric radiation that substances sometimes fall into a sluggish molecular condition, when the responses almost disappear. Strong stimulation (induction shocks, etc.) or annealing is then found to restore the sensitiveness. The same peculiarity is observed in the strain-cell. Lead, for example, specially on cold days, is apt to fall into a sluggish condition, when it becomes almost irresponsive, But it regains its sensitiveness after intense vibration or after annealing.

All metals (including the noble metal Pt) when molecularly disturbed exhibit electromotive effect. The intensity of electromotive variation depends on the nature and physical condition of the substance. The intensity oi effect does not, however, depend on the