Page:Collected Physical Papers.djvu/215

Rh keep the deflection within the scale, a megohm was interposed in the circuit. The resistance of the cell was about 5000 ohms. The absolute values of electromotive force corresponding to the galvanometer deflections were subsequently obtained by noting the effect of a known electromotive force.

Most of the metals—exceptions presently to be described—become negative during molecular disturbance caused by torsion, i.e., the current through the liquid is from the acted to the unacted wire. As there is a considerable vagueness in the terms positive and negative, which has led to much confusion, I would name the acted wire as becoming zincoid or Z, when under an external disturbance the current flows through the electrolyte from the acted to the unacted wire. Again, in certain cases the reverse is true; the current flows from the unacted to the acted wire; the acted wire will in that case be designated as cuproid or C.

The induced electromotive variation is not due to twist as such, but to molecular disturbance induced during increasing twist. For if the wire be held stationary in the twisted position, the molecular disturbance with the attendant electromotive variation will gradually disappear (fig. 43). Other facts will be brought forward to show that the effect is due to the molecular disturbance.

The wires used in the following experiments were from commercial specimens. The length was in every case about 9 cm., but the diameters were not the same.

The responses under electric radiation, and under the stimulus of mechanical vibration will presently be