﻿404 
  Prof. 
  J. 
  Joly 
  on 
  the 
  

  

  upon 
  the 
  large 
  increase 
  of 
  conductivity 
  observed 
  in 
  every 
  

   case 
  but 
  one, 
  the 
  author 
  states 
  that 
  the 
  mean 
  activity 
  shown 
  

   by 
  the 
  twelve 
  measurements 
  is 
  about 
  one-twentieth 
  o£ 
  that 
  of 
  

   a 
  feebly 
  active 
  spring. 
  The 
  experiments 
  were 
  made 
  in 
  calm 
  

   weather. 
  

  

  The 
  interest 
  of 
  the 
  individual 
  results 
  is 
  so 
  considerable 
  

   that 
  I 
  quote 
  the 
  entire 
  series 
  below 
  ; 
  the 
  last 
  column 
  being 
  

   added 
  by 
  me. 
  

  

  Equivalent 
  

   Current. 
  Eadium 
  

   E. 
  S, 
  Units, 
  per 
  litre. 
  

   ITth 
  Sept. 
  1908. 
  12° 
  28' 
  N. 
  24° 
  19' 
  W 
  0-00009 
  12-6 
  

  

  18 
  „ 
  „ 
  8° 
  24' 
  N. 
  26° 
  38' 
  W 
  0-00015 
  21-0 
  

  

  19 
  „ 
  „ 
  4° 
  24' 
  N. 
  28° 
  18' 
  W 
  0-00023 
  32-2 
  

  

  20 
  „ 
  „ 
  0° 
  27' 
  N. 
  30° 
  62' 
  W 
  0-00016 
  22-4 
  

  

  21 
  „ 
  „ 
  3° 
  54' 
  S. 
  32° 
  32' 
  W 
  0-00029 
  40-6 
  

  

  23 
  „ 
  „ 
  12° 
  54' 
  S. 
  35° 
  40' 
  W 
  000000 
  00-0 
  

  

  28 
  „ 
  „ 
  31° 
  48' 
  S. 
  49° 
  40' 
  W 
  0'00006 
  8-4 
  

  

  2 
  Oct. 
  „ 
  42° 
  12' 
  S. 
  59° 
  59' 
  W 
  0-00008 
  11-2 
  

  

  5 
  „ 
  „ 
  Entrance 
  Straits 
  of 
  Magellan. 
  O'OOOIO 
  14-0 
  

  

  6 
  „ 
  „ 
  In 
  Straits 
  of 
  Magellan 
  0-00009 
  12-6 
  

  

  13 
  „ 
  „ 
  Bay 
  of 
  Corral 
  0-00010 
  14-0 
  

  

  15 
  „ 
  „ 
  OfftheBay 
  of 
  Corral 
  0-00010 
  14-0 
  

  

  Assuming 
  that 
  radium 
  in 
  the 
  water 
  is 
  principally 
  respon- 
  

   sible 
  for 
  the 
  observed 
  effect, 
  we 
  may 
  arrive 
  at 
  an 
  approximate 
  

   estimate 
  of 
  the 
  radium 
  in 
  one 
  litre 
  of 
  sea 
  water 
  as 
  shown 
  by 
  

   these 
  experiments. 
  Apparently 
  no 
  deduction 
  is 
  made 
  by 
  the 
  

   author 
  for 
  the 
  effects 
  of 
  the 
  active 
  deposit 
  from 
  the 
  emanation, 
  

   a 
  large 
  part 
  of 
  which 
  would 
  be 
  generated 
  in 
  the 
  electroscope 
  

   during 
  the 
  thirty 
  minutes 
  of 
  observation 
  and 
  the 
  influence 
  of 
  

   which 
  must 
  enter 
  with 
  increasing 
  effect 
  into 
  the 
  potential- 
  

   fall 
  observed. 
  In 
  order 
  not 
  to 
  risk 
  exaggeration 
  of 
  the 
  

   radium 
  I 
  shall 
  assume 
  that 
  the 
  whole 
  of 
  the 
  active 
  deposit 
  is 
  

   concerned 
  in 
  ionizing 
  the 
  air. 
  On 
  Rutherford 
  and 
  Geiger's 
  

   result 
  that 
  in 
  one 
  gram 
  of 
  radium 
  3'4 
  x 
  10^*^ 
  atoms 
  break 
  up 
  

   per 
  second 
  the 
  corresponding 
  emanation, 
  in 
  equilibrium 
  with 
  

   its 
  products 
  of 
  rapid 
  change, 
  should 
  emit 
  about 
  10^^ 
  alpha 
  

   rays 
  per 
  second. 
  Assuming 
  that 
  a 
  total 
  of 
  1*5 
  X 
  10^^ 
  ions 
  (the 
  

   maximum 
  number) 
  are 
  generated 
  by 
  these 
  rays 
  and 
  that 
  

   the 
  charge 
  on 
  the 
  ion 
  is 
  4*6 
  x 
  10 
  "^^ 
  unit, 
  we 
  find 
  that 
  a 
  

   saturation 
  current 
  of 
  0'00012 
  electrostatic 
  unit 
  involves 
  the 
  

   quantity 
  of 
  radium 
  17 
  x 
  10"^^ 
  gram. 
  And 
  this 
  is 
  the 
  amount 
  

   of 
  radium 
  associated 
  with 
  a 
  litre 
  of 
  sea 
  water 
  according 
  to 
  

   the 
  mean 
  of 
  Knoche's 
  results, 
  on 
  the 
  assumption 
  that 
  the 
  

   radium 
  accompanies 
  the 
  emanation. 
  I 
  have 
  made 
  this 
  calcu- 
  

   lation 
  for 
  each 
  of 
  the 
  observations 
  ; 
  for 
  the 
  last 
  column 
  in 
  

  

  