upon the Electrical Discharge in Rarefied Gases. 133 



In the same manner, the bulb, when placed upon the point of 

 greatest magnetic action in such a manner that the platinum elec- 

 trode was horizontal and axial, might be turned rouud in the 

 equatorial plane without the disc of light thus formed under- 

 going any alteration at all. 



41. On making use of the tube before employed, provided 

 with a bulb in the centre of which the negative electrode termi- 

 nated, whose whole length, with the exception of the extremity, 

 was isolated with glass, the corresponding luminous magnetic 

 curve passing through the end of the wire remained always the 

 same, in whichever direction the bulb with its tube was turned 

 around its centre. 



42. In order to discover magnetic light, in the above-de- 

 scribed meaning of the term, experiments were in the first place 

 made with ordinary frictional electricity. The positively charged 

 conductor of an electrical machine, terminating in a sphere, was 

 placed above the great electro-magnet in such a manner that the 

 sphei'e was at a distance of from 20 to 22 centimetres from it. 

 " Brush " discharges wei'e effected from the sphere, which passed 

 to the edges of the armatures, whose rounded ends were ap- 

 proximated to one another and covered with caoutchouc. On 

 exciting the electro-magnet, the brush-discharges remained un- 

 altered. In the same manner I have not been successful in disco- 

 vering any action of the magnet, in the open air, upon the glow, as 

 M. Riess calls it [Glimmliclit) , which appears at the negative pole. 



43. On the other hand, the effect was complete on discharging 

 the positively charged conductor of the machine as it was being 

 turned, through one of Geissler's tubes terminating in bulbs. 

 In this case the platinum electrode of one bulb was brought into 

 contact with the conductor, while the other bulb rested upon 

 the approximated armature. In the latter bulb, that is, in the 

 negative electrode, the magnetic light appeared, which was drawn 

 by the magnetic action into magnetic curves. The phsenomenon 

 appeared continuous to the eye, and the same, only somewhat 

 more feeble, as when lluhrakorff's apparatus was employed. 

 Even when the conductor discharged itself in powerful sparks, 

 which passed to a metallic sphere in contact with the positive 

 electrode, the same appearance presented itself in the neighbour- 

 hood of the magnet at the negative electrode, at every separate 

 discharge. 



When the conductor was charged with negative electricity, no 

 magnetic light appeared abovethe magnet at thepositiveelectrode. 



44. In these experiments also the dark bands were observed 

 in the tube, and the proper electrical light-current was on every 

 occasion aberrated in the same manner as the stream of induc- 

 tion electricity as before described. 



