Page:Collected Physical Papers.djvu/325

Rh 11. The effect of a feeble dose is often opposite to that of a stronger dose.

12. By touching different points of the same wire with different reagents, the excitability of these portions are rendered unequal. Hence a responsive electromotive variation is obtained by stimulating the wire as a whole. The current in the wire is from the less to the more excitable.

13. This method enables the detection of invisible traces of physico-chemical change in a wire.

14. Chemical reagents not only change the excitability but also the quickness of response. Two points having two different rates thus give diphasic and other interference effects. (Proc. Roy. Soc. May 1902.)