Intelligence and Miscellaneous Articles. 373 



ON THE ACTION OF MAGNETISM ON ELECTRICAL DISCHARGES IN 

 DILUTE GASES. BY PROF. BOLTZMANN. 



A flat Geissler's tube in which there was a pressure of 2-5 millim. 

 was placed in a homogeneous magnetic field ; its section at right 

 angles to the lines of force was nearly a rhomb with diagonals of 

 6 and 4 centim. ; its thickness was about 2 centim. The electrodes 

 were fixed at the corners of the rhomb; in tube I. platinum 

 wires were fused in, so that the wires were in the magnetic field ; 

 in the other, II., there were fused glass tubes, in which the wires 

 were sealed some distance outside the magnetic field. The in- 

 duction current of a small RuhmkorfPs coil, with a striking dis- 

 tance of 1 centim., passed through the acute angles of the rhomb 

 (primary electrodes), while the other two electrodes (the transverse 

 electrodes) were connected with a fine-wire galvanometer. The 

 luminous phenomenon in a Greissler's tube, as is well known, is de- 

 flected by magnetism in the same way as a wire traversed by a pri- 

 mary current would be, in accordance with Ampere's rule ; but with 

 a symmetrical position of the tube, and symmetrical position of the 

 transverse electrodes towards the line of junction of the primary 

 current, no conclusion could be drawn, whether, and in what 

 direction a current could be produced by magnetism in the circuit 

 which joined the transverse electrodes. 



Experiment showed now that a current was always produced 

 there, and the place at which the positive current emerged from 

 the tube was always at that transverse electrode from which the 

 band of light was repelled. If therefore this phenomenon is to be 

 compared with that of Hall (Phil. Mag. (5) vol. ix. p. 225), air 

 would behave like bismuth or gold. 



If the tube was filled with H or CO <2 of almost the same pressure, 

 these gases showed neither qualitatively nor quantitatively a demon- 

 strable difference in comparison with air. In tube I. the current 

 between the transverse electrodes was in the mean about the six- 

 tieth, and in the maximum about the thirtieth of the primary 

 current with a field of about 1800 (C.Gr.S.) ; yet this number can 

 only give an approximation to the order of magnitude, since the cir- 

 cuit to the galvanometer was quite inadequately insulated for cur- 

 rents of such potential ; and since from the electromotive force, 

 which according to Edlund appears at the electrodes, the intensity 

 of the current could not be taken as proportional to the electromo- 

 tive force of the primary or the transverse current. In tube II. the 

 transverse current was much smaller, probably because in addition 

 to the rhomb it had also to traverse the narrow glass tubes. 



In these experiments the inductorium, and the battery which 

 worked it (2-3 chromic acid elements), were insulated on sealing- 

 wax rods, so that without the action of magnetism electricity could 

 neither enter nor emerge in large quantities through the transverse 

 electrodes. This arrangement is quite in correspondence with that 



