﻿Homogeneous 
  Secondary 
  Rontgen 
  Radiations. 
  555 
  

  

  secondary 
  cathode 
  particles 
  are 
  not 
  directed 
  like 
  the 
  primary 
  

   cathode 
  rays, 
  they 
  produce 
  radiation 
  which 
  is 
  not 
  polarized. 
  

   The 
  greater 
  the 
  number 
  of 
  secondary 
  cathode 
  particles 
  pro- 
  

   duced, 
  the 
  less 
  is 
  the 
  polarity 
  of 
  the 
  complex 
  radiation. 
  As 
  

   the 
  X-radiation 
  from 
  the 
  secondary 
  cathode 
  particles 
  is 
  

   probably 
  less 
  penetrating 
  than 
  that 
  due 
  to 
  the 
  primary 
  

   cathode 
  particles, 
  the 
  more 
  penetrating 
  portion 
  of 
  the 
  

   complex 
  X-radiation 
  exhibits 
  slightly 
  more 
  polarity 
  than 
  

   the 
  more 
  easily 
  absorbed. 
  

  

  The 
  small 
  increase 
  observed 
  in 
  the 
  intensity 
  of 
  secondary 
  

   radiation 
  from 
  air, 
  paper, 
  &c., 
  as 
  measured 
  by 
  the 
  ionization 
  

   produced 
  in 
  an 
  electroscope, 
  when 
  the 
  primary 
  beam 
  is 
  made 
  

   more 
  penetrating, 
  is 
  possibly 
  due 
  to 
  the 
  superposition 
  of 
  a 
  

   homogeneous 
  unscattered 
  radiation, 
  such 
  as 
  is 
  emitted 
  by 
  

   elements 
  of 
  higher 
  atomic 
  weight. 
  This 
  would 
  account 
  for 
  

   the 
  complex 
  secondary 
  radiation 
  differing 
  more 
  and 
  more 
  in 
  

   penetrating 
  power 
  from 
  the 
  primary 
  as 
  the 
  latter 
  became 
  

   more 
  penetrating 
  ; 
  for 
  it 
  has 
  a 
  definite 
  penetrating 
  power 
  

  

  characteristic 
  merely 
  of 
  the 
  element 
  emitting- 
  it. 
  Though 
  

  

  j 
  © 
  © 
  

  

  experiments 
  have 
  not 
  yet 
  been 
  made 
  to 
  analyse 
  this 
  secondary 
  

   radiation 
  set 
  up 
  by 
  the 
  more 
  penetrating 
  radiation, 
  it 
  appears, 
  

   for 
  reasons 
  discussed 
  later, 
  exceedingly 
  probable 
  that 
  such 
  a 
  

   radiation 
  does 
  appear 
  w 
  T 
  hen 
  a 
  penetrating 
  primary 
  beam 
  is 
  

   used. 
  

  

  A 
  point 
  still 
  awaiting 
  investigation 
  is 
  the 
  change 
  in 
  the 
  

   observed 
  ratio 
  of 
  intensities 
  of 
  secondary 
  radiation 
  in 
  direc- 
  

   tions 
  approximately 
  opposite 
  and 
  perpendicular 
  to 
  that 
  of 
  

   primary 
  propagation. 
  Experiments 
  have 
  been 
  made 
  to 
  

   ascertain 
  the 
  amount 
  by 
  which 
  this 
  ratio 
  is 
  affected 
  by 
  a 
  

   change 
  in 
  the 
  polarization 
  of 
  the 
  primary 
  beam, 
  by 
  the 
  

   superposition 
  of 
  tertiary 
  rays 
  in 
  greater 
  proportion, 
  and 
  

   by 
  the 
  superposition 
  of 
  homogeneous 
  radiation 
  characteristic 
  

   of 
  the 
  radiating 
  element. 
  In 
  these 
  later 
  experiments, 
  how- 
  

   ever, 
  the 
  deviation 
  from 
  the 
  theoretical 
  ratio 
  for 
  perfect 
  

   scattering 
  has 
  through 
  all 
  the 
  changes 
  made 
  in 
  the 
  primary 
  

   beam 
  been 
  much 
  less 
  than 
  in 
  the 
  first 
  experiments 
  ; 
  and 
  it 
  

   has 
  been 
  found 
  that 
  even 
  a 
  fairly 
  penetrating 
  primary 
  beam 
  — 
  

   much 
  more 
  penetrating 
  than 
  any 
  used 
  in 
  the 
  experiments 
  

   referred 
  to 
  in 
  a 
  previous 
  paper 
  (a) 
  — 
  sets 
  up 
  secondary 
  rays 
  

   whose 
  intensity 
  distribution 
  is 
  within 
  a 
  few 
  per 
  cent, 
  of 
  that 
  

   which 
  would 
  be 
  given 
  by 
  perfect 
  scattering. 
  This 
  matter 
  is 
  

  

  being 
  further 
  investigated 
  *. 
  

  

  © 
  © 
  

  

  * 
  It 
  ought 
  to 
  be 
  remarked, 
  that 
  though 
  au 
  elementary 
  consideration 
  

   of 
  the 
  production 
  of 
  secondary 
  rays 
  indicates 
  that 
  the 
  intensity 
  of 
  

   radiation 
  is 
  the 
  same 
  in 
  the 
  forward 
  and 
  backward 
  directions, 
  and 
  that 
  

   each 
  of 
  these 
  is 
  double 
  that 
  in 
  a 
  direction 
  at 
  right 
  angles, 
  a 
  more 
  complete 
  

  

  