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  XLVII. 
  Magnetic 
  Rotation 
  of 
  Electric 
  Discharge. 
  

   By 
  Prof. 
  D. 
  N. 
  Mallik, 
  B.A., 
  Sc.D., 
  F.R.S.E.* 
  

  

  [Plate 
  XXI.] 
  

  

  1. 
  TITHE 
  present 
  paper 
  presents 
  a 
  detailed 
  study 
  of 
  the 
  

   JL 
  properties 
  of 
  the 
  electric 
  discharge 
  in 
  De 
  La 
  Rive's 
  

   apparatus. 
  

  

  The 
  apparatus 
  is 
  of 
  the 
  usual 
  form. 
  The 
  vacuum-tube, 
  

   however, 
  is 
  in 
  communication 
  with 
  a 
  pump 
  and 
  an 
  ordinary 
  

   barometric 
  gauge. 
  An 
  aluminium 
  disk 
  and 
  ring 
  of 
  the 
  same 
  

   material 
  form 
  the 
  electrodes. 
  

  

  Fig. 
  1. 
  

  

  The 
  electromagnet 
  (E, 
  E) 
  is, 
  as 
  usual, 
  made 
  up 
  of 
  a 
  coil 
  

   carrying 
  current 
  and 
  a 
  soft 
  iron 
  core 
  projecting 
  from 
  it. 
  

   The 
  discharge 
  (in 
  most 
  of 
  the 
  experiments) 
  is 
  passed 
  from 
  an 
  

   induction-coil, 
  the 
  E.AI.F. 
  of 
  which 
  is 
  varied 
  by 
  changing 
  the 
  

   number 
  of 
  cells 
  in 
  the 
  primary 
  circuit. 
  

  

  2. 
  As 
  the 
  pump 
  is 
  worked, 
  it 
  is 
  found 
  that 
  at 
  a 
  certain 
  

   pressure 
  depending 
  on 
  the 
  number 
  of 
  cells 
  in 
  the 
  primary 
  of 
  

   the 
  induction-coil, 
  i.e. 
  the 
  E.M.F. 
  of 
  the 
  induction-coil, 
  and 
  

  

  * 
  Communicated 
  "by 
  the 
  Author. 
  

  

  2N2 
  

  

  