Discharge in Rarefied Gases. 379 



formed in the phosphorescent surfaces excited by the positive 

 light, and their position indicate similar behaviour. If the 

 electric rays in the kathode-light proceeded from its exterior 

 boundary towards the kathode, and in the secondary negative 

 and positive pencils from the side of the anode towards the 

 side of the kathode, then, on introducing an object, the pencil 

 of rays would, on the contrary, remain intact from the exte- 

 rior boundary up to the object, and the shadows would appear 

 upon the wall upon the kathode side of the object. 



Another argument for propagation in the direction of the 

 negative current is found in the phenomenon described above, 

 that the properties of secondary negative rays are, even for 

 considerable distances, such as correspond to the conditions 

 which exist at the negative boundary of the pencil of rays — 

 that is, the one nearest to the kathode. The pencil, which 

 with increasing evacuation radiates continually more and more 

 from the mouth of a narrow tube opening into a wider 

 vessel, contains rays possessing the properties of the light of 

 narrow tubes. If the pencil had its origin in the wider 

 vessel and propagated itself from it into the narrower tube, 

 we should expect to find its properties more in accordance 

 with the conditions of discharge offered by wide tubes. The 

 pencil between a narrow cylinder and a wider one following 

 upon this upon the side of the anode would show then the 

 same colour and spectrum as those pencils which have their 

 origin in the wide cylinder and compose the column of its 

 positive stratifications. 



A further criterion for the direction in which the electric 

 rays propagate themselves is found in their magnetic behaviour 

 as described above for the kathode-rays, in accordance with 

 Hittorf's conclusions. 



It is characteristic of this behaviour that if a (sufficiently 

 weak) magnet is allowed to act upon the end of a long 

 kathode-pencil remote from the kathode, only this end is 

 affected by the magnet, whilst those portions of the pencil 

 near the kathode retain their form and position unaltered. 

 If the magnet is brought into the neighbourhood of the kathode 

 itself so as to act upon the portions of the rays nearest the 

 kathode, then the whole pencil is deflected together with these 

 portions even to its furthest point, upon which, in consequence 

 of its great distance, the magnet could exert no action directly. 



The electric particles (or the electric motion) at the end of 

 the ray remote from the kathode therefore follows the direc- 

 tion impressed upon the particles at the kathode itself ; but 

 the particles at the kathode are not influenced by action upon 

 the particles at the further end. Roth phenomena agree with 

 2C 2 



