Discharge of Electricity through Gases. 335 



the action which takes place at the poles in an electrolyte as a 

 condenser action, and we can calculate from the measured capacity of 

 the condenser the distance between the two charges of electricity. 

 In the case of liquids, this distance is extremely small, and is given 

 by Helmholtz in his Faraday lecture as the ten-millionth part of a 

 millimetre. Though the total fall of potential in a gas which is 

 measured by the moment of the condenser might be the same as, or 

 even much stronger than in the liquid, the charges might easily escape 

 detection, if the distance between the layers is say ten thousand 

 times larger in the gas than in the liquid. The phenomenon of the 

 dark area tends to argue in favour of a greater thickness of the 

 region between which the condenser action takes place. 



The Positive Part of the Discharge. 



I cannot enter in the present paper fully into the phenomena which 

 happen in the positive part of the discharge. It is too early as yet, I 

 think, to form a distinct idea as to how the electricity is conveyed in 

 the manifold forms which the discharge seems able to take. But a 

 few remarks may not be out of place to show that we meet with 

 nothing that is contradictory to the theory which I have put forward. 

 A remarkable result obtained in different ways by Hittorf and by 

 E. Wiedemann is on the contrary rather in its favour. Hittorf has 

 found that the fall of potential in that part of the tube which we have 

 for convenience' sake called the positive half, is independent of the 

 intensity of the current passing through it. This means that the 

 current into the resistance is a constant quantity for a given tube and 

 pressure, or in other words, that the energy dissipated is directly 

 proportional to the current, and not to the square of the current as in 

 !a metallic conductor. It had, indeed, been found previously by 

 E. Wiedemann that the heat developed in a series of discharges is 

 proportional to the quantity of electricity which has passed through 

 the tube, and independent of the fact whether that quantity has 

 passed in a few strong sparks or in a greater number of weaker ones. 

 This fact seems to point to the conclusion that in the positive part of 

 the discharge a greater intensity of current only means that a greater 

 number of particles takes part in the discharge, but that the velocity 

 of diffusion of the particles carrying the discharge is independent of 

 the intensity of the current. 



With regard to the stratifications, I should offer the following 

 preliminary explanation, but only with the view of showing that the 

 theory is capable of dealing with these phenomena. In the first place 

 stratifications are seen at their best with compound gases, and also 

 with mixtures of gases which are likely to form compounds. That 

 the decomposed particles at the negative pole are liable to form 



