Page:Collected Physical Papers.djvu/309

Rh of response is earlier when the applicaticin of Na$2$CO$3$ is fresh. In the experiment whose record is given, the wire is held at one end, and successive uniform vibrations imparted to the wire as a whole at intervals of one minute by means of a torsion head at the other end. Owing to after-effect of previous applications of Na$2$CO$3$, the sensitiveness of A is at the beginning great, hence the resultant response at the commencement is positive or upward. Dilute solution of Na$2$CO$3$ is next applied to B. The response of B (down) begins earlier, and continues to grow

stronger and stronger. The response therefore shows a preliminary negative twitch of B followed by positive variation of A. The negative grows continuously. At the fifth response, the two components, negative and positive, of the double response become equal; after that, the negative becomes very prominent, the positive dwindling into a feeble and inconspicuous response.