﻿196 
  Prof. 
  J. 
  Joly 
  on 
  the 
  Radium- 
  Content 
  

  

  The 
  Red 
  Clay 
  of 
  Chall. 
  Station 
  276 
  might 
  appear 
  to 
  be 
  

   exceptional. 
  It 
  is, 
  however, 
  recorded 
  of 
  this 
  clay 
  that 
  the 
  

   dredge 
  came 
  up 
  with 
  many 
  manganese 
  nodules 
  and 
  sharks' 
  

   teeth. 
  This 
  is 
  evidence 
  of 
  high 
  antiquity. 
  The 
  richness 
  in 
  

   calcium 
  carbonate 
  of 
  this 
  clay 
  may 
  be 
  due 
  to 
  conditions 
  no 
  

   longer 
  prevailing. 
  

  

  It 
  might 
  be 
  inferred 
  from 
  a 
  priori 
  considerations 
  that 
  the 
  

   uranium 
  which 
  is 
  parent 
  to 
  the 
  radium 
  must 
  be 
  present 
  

   either 
  in 
  the 
  waters 
  o£ 
  the 
  ocean 
  or 
  in 
  its 
  deposits 
  : 
  for 
  it 
  is 
  

   evident 
  that 
  a 
  substance 
  so 
  perishable 
  as 
  radium 
  — 
  disappearing 
  

   in 
  a 
  very 
  few 
  thousand 
  years 
  — 
  cannot 
  be 
  supplied 
  from 
  the 
  

   land 
  at 
  a 
  rate 
  adequate 
  to 
  make 
  good 
  its 
  disappearance 
  from 
  

   so 
  vast 
  a 
  reservoir. 
  Again, 
  we 
  have 
  the 
  evidence 
  of 
  the 
  

   Chalk, 
  &c, 
  that 
  uranium 
  must 
  enter 
  precipitated 
  deposits. 
  In 
  

   the 
  legitimacy 
  of 
  any 
  deductions 
  which 
  may 
  be 
  founded 
  on 
  

   the 
  high 
  radioactivity 
  of 
  the 
  deep-sea 
  oceanic 
  sediments, 
  

   however, 
  it 
  was 
  necessary 
  to 
  ascertain 
  whether 
  uranium 
  

   actually 
  existed 
  in 
  these 
  radioactive 
  deposits. 
  So 
  far 
  as 
  I 
  am 
  

   aware 
  this 
  substance 
  has 
  not 
  hitherto 
  been 
  found 
  either 
  with 
  

   manganese 
  nodules 
  or 
  in 
  the 
  Cozes 
  and 
  Clays. 
  In 
  the 
  

   nodules 
  it 
  has 
  been 
  sought 
  in 
  vain 
  (' 
  Challenger 
  ' 
  Report, 
  

   p. 
  419). 
  Mr. 
  Pollock, 
  of 
  the 
  Royal 
  College 
  of 
  Science, 
  

   Dublin, 
  who 
  has 
  done 
  so 
  much 
  to 
  extend 
  the 
  availability 
  of 
  

   Professor 
  Hartley's 
  spectroscopic 
  methods 
  of 
  quantitative 
  

   analysis, 
  after 
  going 
  fully 
  into 
  the 
  matter 
  found 
  that 
  the 
  

   spectroscope 
  was 
  not 
  sufficiently 
  sensitive 
  for 
  the 
  research 
  

   owing 
  to 
  the 
  lack 
  of 
  distinctive 
  and 
  accentuated 
  uranium 
  

   lines. 
  On 
  the 
  other 
  hand, 
  following 
  the 
  method 
  of 
  P. 
  H. 
  

   Walker 
  (Journ. 
  Amer. 
  Chem. 
  Soc. 
  1898, 
  p. 
  20). 
  Professor 
  

   Werner, 
  of 
  Trinity 
  College, 
  successfully 
  established 
  the 
  

   presence 
  of 
  uranium, 
  and 
  even 
  obtained 
  an 
  approximate 
  

   colorimetric 
  estimate 
  of 
  its 
  amount 
  in 
  the 
  S'4:2 
  grams 
  of 
  the 
  

   Red 
  Clay 
  of 
  Chall. 
  Station 
  276, 
  as 
  used 
  in 
  the 
  experiment 
  

   given 
  above. 
  In 
  a 
  letter 
  dated 
  28th 
  April, 
  Werner 
  writes 
  : 
  

   " 
  One 
  can 
  say 
  without 
  doubt 
  that 
  the 
  uranium 
  is 
  present 
  — 
  

   not 
  less 
  than 
  O0006 
  and 
  not 
  more 
  than 
  0*0007. 
  It 
  is 
  

   difficult, 
  however, 
  to 
  be 
  sure 
  that 
  one 
  has 
  got 
  all 
  the 
  uranium. 
  

   so 
  that 
  the 
  result 
  probably 
  underestimates 
  the 
  real 
  thing." 
  

   The 
  theoretical 
  quantity 
  of 
  uranium 
  present 
  in 
  the 
  8*42 
  grams 
  

   would 
  be 
  0012. 
  

  

  The 
  result 
  on 
  the 
  magnetic 
  particles 
  seems 
  to 
  show 
  that 
  

   the 
  cosmic 
  particles 
  which 
  Sir 
  John 
  Murray 
  detected 
  in 
  the 
  

   slow-forming 
  Oozes 
  cannot 
  be 
  regarded 
  as 
  concerned 
  in 
  the 
  

   supply 
  of 
  radium 
  or 
  uranium 
  to 
  the 
  ocean. 
  It 
  would 
  there- 
  

   Bore 
  be 
  inferred 
  thai 
  the 
  oceanic 
  radioactive 
  elements 
  are 
  

  

  