Passage of Electricity through Gases. 179 



them, does a close aggregation ensue ; the heat and brightness 

 then become greater, and are transmitted, as stated above, 

 from particle to particle. Possibly, after the first collision, a 

 large number of consecutive equally charged molecules may 

 travel some distance without a fresh collision between each 

 other, in the same way as the molecules which first left the ne- 

 gative electrode ; and they may only then transmit their charge 

 to the unelectric molecules beyond them. In this way lighter 

 and darker patches may appear alternately, forming the well- 

 known strise. 



At the positive electrode the discharge begins at a much 

 higher charge than at the negative. With the same supply of 

 electricity it will pass in a much shorter time. The gas 

 molecules thrown off from it will be fewer ; but they will be 

 more highly charged, and will move from it with great velo- 

 city. The dark space, therefore, disappears. Only in par- 

 ticular cases does it exist to a smaller extent, viz. when the 

 electrodes are directly connected with the machine, and when 

 an air-spark is introduced at the negative electrode, by which 

 means a reverse discharge of the tube, which has been charged 

 by the positive electrode, may commence through the latter 

 before the spark can break through the interval at the nega- 

 tive electrode. 



I do not deny that many experiments will be needed to 

 prove these theories. But they essentially comprise the phe- 

 nomena under one general aspect, which involves no suppo- 

 sitions beyond those involved in our previous theories of the 

 nature of electricity. The great difficulty and complication 

 of the phenomena may make this preliminary statement not 

 wholly needless ; and I hope to be able to supply some further 

 contributions hereafter. 



We ought now to examine whether and how far the above 

 mentioned researches, and the differences deduced from them 

 as to the behaviour of the discharges at the positive and 

 negative electrodes (which for brevity we may generally 

 term positive and negative discharges), will explain the very 

 interesting and remarkable details of their outward appearance, 

 noticed more particularly by Hittorf*, with electrodes of 

 different forms. We must necessarily limit ourselves on this 

 point to some of the more simple phenomena. 



If, for example, instead of spherical electrodes in spherical 

 glass tubes, cylindrical (wire) electrodes in cylindrical tubes 



* Cf. Galvanismus (2), Bd. ii. S. 954, u. Fig. 



N2 



