Electric discharge with the chloride of silver battery. 109 
3. When the discharge takes place there is a sudden dilatation of the medium in 
addition to and distinct from, that caused hy heat. This dilatation ceases 
instantaneously when the discharge ceases. 
4. The potential necessary to produce a discharge bet ween parallel flat surfaces at a 
constant distance and various pressures, or at a constant pressure and various 
distances, may be represented by hyperbolic curves. The resistance to the 
discharge between parallel flat surfaces being as the number of molecules 
intervening between them. 
5. This law does not hold with regard to points. In Part I. it has been shown that 
the potential necessary to produce a discharge at the atmospheric pressure 
and various distances is as the square root of the distances; while with 
a constant potential and various distances, the pressure has to be diminished 
in a greater ratio than that of the increase of distance in order to permit a 
discharge to take place. 
6. The electric arc and the stratified discharge in vacuum tubes are modifications of 
the same phenomenon. 
We propose later on to follow up this communication with an account of some 
researches on the conditions of the dark discharge and of special phenomena of the 
negative discharge. We have also made preparations for constructing the terminals 
of the tubes of very small platinum tube, in order to permit of gas being admitted 
through them during the discharge. 
We have again pleasure in thanking Professor Stokes for his much-valued advice 
during the course of our investigations. To our assistant, Mr. Fram, we are indebted 
for his able co-operation, and we have to thank Mr. H. Reynolds for his aid and skill 
in taking photographs. 
