Page:Collected Physical Papers.djvu/268

248 Figure 58 exhibits the variation of resistance under increasing E. M. F. described in the table VI.

But the most astonishing thing about the action of the receiver was that in taking the return curve, I found it practically coinciding in every part with the forward curve, so that when the E. M. F. was brought back to its initial value of 0·1 volt, the receiver had completely returned by its original path to its first condition, there being no residual effect. I repeated the experiment many times in succession, but the curves obtained, whether forwards or backwards, were in every case merely superposed on the original. Since the condition of the receiver is exactly the same after many cycles as at the beginning, it is evident that the conductivity variation could not be due essentially to any chemical change, for such changes are irreversible.

The increase of conductivity with increase of E. M. F. is not due to any sudden breakdown, such as fusion