﻿584 
  Mr. 
  J. 
  Satterly 
  on 
  the 
  Amount 
  of 
  

  

  were 
  merely 
  held 
  by 
  a 
  body 
  or! 
  much 
  greater 
  mass, 
  we 
  

   should 
  expect 
  the 
  emission 
  of 
  wave-trains 
  instead 
  of 
  pulses, 
  

   yet 
  if 
  the 
  atomic 
  system 
  consisted 
  of 
  a 
  number 
  of 
  interacting 
  

   electrons, 
  the 
  energy 
  of 
  vibration 
  would 
  be 
  rapidly 
  commu- 
  

   nicated 
  to 
  other 
  parts 
  of 
  the 
  system 
  and 
  the 
  motion 
  of 
  the 
  

   displaced 
  electron 
  would 
  be 
  little 
  more 
  than 
  half 
  a 
  complete 
  

   vibration. 
  The 
  resultant 
  radiation 
  would 
  in 
  that 
  case 
  behave 
  

   much 
  as 
  a 
  number 
  of 
  isolated 
  pulses. 
  

  

  An 
  explanation 
  on 
  the 
  disruption 
  theory 
  would 
  be 
  similar 
  

   in 
  many 
  respects, 
  but 
  the 
  displacement 
  of 
  electrons 
  would 
  on 
  

   such 
  a 
  theory 
  be 
  sufficient 
  to 
  destroy 
  the 
  equilibrium 
  of 
  the 
  

   atomic 
  system 
  and 
  produce 
  some 
  change 
  in 
  its 
  structure. 
  The 
  

   evidence 
  against 
  this 
  is 
  perhaps 
  not 
  conclusive, 
  but 
  there 
  is 
  no 
  

   indication 
  from 
  the 
  energy 
  of 
  secondary 
  X-radiation 
  of 
  such 
  

   a 
  phenomenon, 
  and 
  the 
  relation 
  between 
  the 
  primary 
  and 
  

   secondary 
  radiations 
  points 
  rather 
  to 
  the 
  latter 
  being 
  due 
  to 
  

   the 
  motion 
  of 
  the 
  atomic 
  system 
  in 
  regaining 
  its 
  normal 
  

   configuration. 
  

  

  George 
  Holt 
  Physics 
  Laboratory, 
  

   University 
  of 
  Liverpool, 
  

   30th 
  May, 
  1908. 
  

  

  XLIX. 
  The 
  Amount 
  of 
  Radium 
  Emanation 
  in 
  the 
  Atmosphere. 
  

   By 
  John 
  Satterly, 
  A.R.C.Sc, 
  B.Sc, 
  B.A., 
  St. 
  Johns 
  

   College, 
  Cambridge*. 
  

  

  IN 
  1900 
  Elster 
  and 
  Geitel 
  f 
  found 
  that 
  when 
  a 
  negatively 
  

   electrified 
  wire 
  was 
  exposed 
  to 
  the 
  atmosphere 
  for 
  some 
  

   time 
  a 
  radioactive 
  deposit 
  was 
  formed 
  on 
  it 
  whose 
  properties 
  

   agreed 
  very 
  closely 
  with 
  the 
  properties 
  of 
  the 
  active 
  deposit 
  

   from 
  radium. 
  Blanc 
  J 
  and 
  others 
  have 
  shown 
  that 
  a 
  thorium 
  

   deposit 
  accompanies 
  the 
  radium 
  deposit, 
  the 
  relative 
  amounts 
  

   of 
  the 
  two 
  deposits 
  being 
  dependent 
  on 
  the 
  time 
  of 
  exposure 
  

   of 
  the 
  wire. 
  Eve 
  § 
  compared 
  the 
  amount 
  of 
  the 
  active 
  

   deposit 
  obtained 
  from 
  a 
  known 
  volume 
  of 
  air 
  with 
  the 
  active 
  

   deposit 
  obtained 
  from 
  the 
  emanation 
  generated 
  by 
  a 
  solution 
  

   of 
  radium 
  bromide 
  of 
  known 
  strength, 
  and 
  in 
  this 
  way 
  

   formed 
  an 
  estimate 
  of 
  the 
  amount 
  of 
  radium 
  necessary 
  to 
  

   keep 
  up 
  the 
  supply 
  of 
  emanation. 
  Strutt 
  ||, 
  Eve 
  If, 
  Joly 
  ** 
  

  

  * 
  Communicated 
  by 
  Prof. 
  J. 
  J. 
  Thomson, 
  F.P.S. 
  

   + 
  Elster 
  and 
  Geitel, 
  Phys. 
  Zeit. 
  ii. 
  1901. 
  

  

  % 
  Blanc, 
  Phil. 
  Mag. 
  Mar. 
  1907. 
  Also 
  Dadourian, 
  Le 
  Radium, 
  April 
  

   1908. 
  

  

  § 
  Eve, 
  Phil. 
  Mag. 
  July 
  1905. 
  

  

  II 
  Strutt, 
  Proc. 
  Boy. 
  Soc. 
  May 
  1905, 
  May 
  and 
  Aug. 
  1906. 
  

   1[ 
  Eve 
  and 
  Macintosh, 
  Phil. 
  Mag. 
  Aug. 
  1907. 
  

   ** 
  Joly, 
  Phil. 
  Mag. 
  Mar. 
  1908. 
  

  

  