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  XIII. 
  On 
  tlie 
  Radium- 
  Content 
  of 
  Deep-Sea 
  Sediments. 
  By 
  

   J. 
  Joly, 
  Sc.D., 
  F.R.S., 
  Professor 
  of 
  Geology 
  and 
  Mine- 
  

   ralogy 
  in 
  the 
  University 
  of 
  Dublin* 
  . 
  

  

  IN 
  a 
  paper 
  appearing 
  in 
  the 
  Philosophical 
  Magazine 
  of 
  

   March 
  this 
  present 
  year 
  I 
  have 
  recorded 
  some 
  ex- 
  

   periments 
  which 
  appear 
  to 
  show 
  that 
  sea- 
  water 
  possesses 
  a 
  

   richness 
  in 
  radium 
  not 
  hitherto 
  suspected. 
  

  

  Although 
  the 
  actual 
  amount 
  of 
  radium 
  per 
  cubic 
  centimetre 
  

   is 
  minute 
  (approximating 
  to 
  0*02 
  x 
  10~ 
  12 
  grams), 
  the 
  quantity 
  

   distributed 
  in 
  the 
  ocean 
  is, 
  of 
  course, 
  enormous. 
  We 
  do 
  not 
  

   as 
  yet 
  know 
  in 
  what 
  state 
  the 
  radioactive 
  matter 
  exists 
  in 
  the 
  

   water 
  — 
  whether 
  in 
  true 
  solution, 
  or 
  as 
  (possibly) 
  a 
  precipitate 
  

   or 
  dust 
  in 
  suspension. 
  I 
  have 
  found 
  in 
  some 
  recent 
  experi- 
  

   ments 
  that 
  a 
  part 
  of 
  the 
  radium 
  may 
  be 
  filtered 
  from 
  sea- 
  

   water 
  which 
  contains 
  much 
  organic 
  matter 
  and 
  has 
  been 
  left 
  

   standing 
  some 
  weeks. 
  Possibly 
  it 
  is 
  piecipitated 
  as 
  a 
  sulphate 
  

   by 
  bacterial 
  actions 
  in 
  the 
  decomposing 
  organic 
  particles. 
  

   This 
  observation 
  may 
  have 
  a 
  bearing 
  on 
  the 
  results 
  obtained 
  

   on 
  deep-sea 
  sediments 
  which 
  I 
  have 
  now 
  to 
  record. 
  But 
  

   whether 
  this 
  be 
  so 
  or 
  not, 
  it 
  is 
  certainly 
  in 
  harmony 
  with 
  the 
  

   high 
  radioactivity 
  of 
  sea-water 
  to 
  find 
  that 
  the 
  deep-lying 
  

   sediments 
  of 
  the 
  ocean 
  are 
  exceptionally 
  rich 
  in 
  radium 
  — 
  

   far 
  richer 
  than 
  average 
  terrestrial 
  rocks. 
  

  

  The 
  materials 
  dealt 
  with 
  in 
  the 
  following 
  experiments 
  are 
  

   partly 
  from 
  the 
  'Challenger/ 
  partly 
  from 
  the 
  ' 
  Albatross 
  ' 
  

   collections. 
  I 
  owe 
  these 
  to 
  the 
  kindness 
  of 
  Sir 
  John 
  Murray, 
  

   F.R.S. 
  For 
  a 
  specimen 
  of 
  Globigerina 
  Ooze, 
  brought 
  up 
  

   in 
  trawling, 
  I 
  have 
  to 
  thank 
  Mr. 
  S. 
  W. 
  Kemp, 
  of 
  the 
  Irish 
  

   Fishery 
  Department, 
  and 
  for 
  a 
  specimen 
  of 
  the 
  mud 
  elevated 
  

   by 
  the 
  volcanic 
  disturbance 
  of 
  1906, 
  in 
  the 
  Bay 
  of 
  Bengal, 
  

   Mr. 
  Stephen 
  Dawson, 
  (J.E. 
  

  

  Although 
  these 
  materials 
  have 
  been 
  in 
  my 
  possession 
  for 
  

   some 
  months, 
  most 
  of 
  the 
  experiments 
  are 
  of 
  recent 
  date, 
  and 
  

   where 
  two 
  are 
  recorded, 
  the 
  second 
  is, 
  in 
  every 
  case, 
  a 
  recent 
  

   re-examination 
  of 
  the 
  same 
  material. 
  The 
  reason 
  for 
  this 
  

   postponement 
  was 
  my 
  desire 
  to 
  arrive 
  at 
  a 
  fuller 
  knowledge 
  

   of 
  the 
  most 
  reliable 
  conditions 
  of 
  investigation 
  before 
  using 
  

   up 
  material 
  of 
  such 
  value. 
  In 
  the 
  process 
  of 
  acquiring 
  

   experience 
  of 
  the 
  experimental 
  difficulties 
  involved, 
  various 
  

   methods 
  of 
  extracting 
  the 
  emanation 
  were 
  tried. 
  According 
  

   to 
  the 
  nature 
  of 
  the 
  substance 
  these 
  methods 
  have 
  been 
  applied 
  

   in 
  the 
  observations 
  on 
  deep-sea 
  deposits. 
  It 
  would 
  be 
  out 
  

   of 
  place 
  to 
  consider 
  these 
  methods 
  here, 
  and 
  their 
  relative 
  

  

  * 
  Printed 
  with 
  additions 
  from 
  tli" 
  Proceedings 
  Royal 
  Dublin 
  Society, 
  

   vol. 
  xi. 
  p. 
  288. 
  Communicatee! 
  by 
  the 
  Author. 
  

  

  