Page:Collected Physical Papers.djvu/222

the curve similar to that of Ag′ under electric stimulus mentioned above. Also the effects of different intensities of vibration, as shown in figure 45, (a) and (b).

Fig. 45. Effect of continuous vibration. (a) and (b) show effects on a Tin cell. In (c) the effect on the particular Silver cell; the sign of E. M. variation is opposite to that of Tin cell. (d) shows the effect on a Nickel cell.

In (d) is shown the effect of vibration on Ni. After reaching the maximum there is a tendency towards reversal. Ni also shows greater signs of fatigue.

In (c), fig. 45, is shown the interesting curve for a given piece of Ag. The effect is very much feebler, and curiously enough it gave response of an opposite sign, the vibrated wire becoming cuproid. It was said that silver occupied a peculiar position as regards response to electric radiation, sometimes responding in one, and again in an opposite manner, probably owing to its readiness to pass from one molecular condition to another, under slightly different external conditions. With mechanical vibration, too, I find silver, exhibiting