﻿Rad'iam 
  present 
  in 
  Sea- 
  Water, 
  105 
  

  

  Nevertheless 
  it 
  might 
  be 
  objected 
  that 
  the 
  radium 
  emanation 
  

   is 
  absorbed 
  by 
  bubbling 
  through 
  water 
  to 
  a 
  variable 
  and 
  

   unknown 
  extent. 
  Therefore 
  re-determinations 
  were 
  made 
  by 
  

   collecting 
  over 
  mercury. 
  There 
  was 
  no 
  certain 
  observable 
  

   difference 
  between 
  the 
  two 
  methods. 
  It 
  is 
  often 
  simpler 
  and 
  

   it 
  seems 
  perfectly 
  safe 
  to 
  collect 
  over 
  water. 
  

  

  To 
  calibrate 
  the 
  electroscope 
  1 
  prepared 
  solutions 
  of 
  radium 
  

   bromide, 
  using 
  those 
  standard 
  solutions 
  whose 
  history 
  is 
  given 
  

   in 
  the 
  American 
  Journal 
  of 
  Science, 
  vol. 
  xxii. 
  July 
  1906. 
  

   These 
  same 
  standard 
  solutions 
  were 
  those 
  also 
  used 
  by 
  

   Rutherford 
  and 
  Bolt 
  wood 
  in 
  their 
  determinations 
  of 
  the 
  

   ratio 
  of 
  uranium 
  to 
  radium 
  in 
  pitchblende. 
  As 
  Joly 
  used 
  

   this 
  ratio 
  for 
  calibration, 
  our 
  standards 
  are 
  practically 
  the 
  

   same. 
  Moreover 
  Strutt, 
  Joly, 
  Eve 
  and 
  Mcintosh 
  all 
  find 
  

   values 
  for 
  the 
  radium 
  contents 
  of 
  rocks 
  which 
  are 
  in 
  satis- 
  

   factory 
  agreement, 
  so 
  that 
  the 
  question 
  of 
  relative 
  standards 
  

   does 
  not 
  arise. 
  

  

  One 
  c.c. 
  of 
  the 
  standard 
  solution, 
  containing 
  I'oTxlO"^ 
  

   gram 
  of 
  radium, 
  was 
  taken 
  with 
  a 
  new 
  and 
  clean 
  pipette 
  

   and 
  placed 
  in 
  a 
  flask 
  with 
  99 
  c.c. 
  of 
  distilled 
  water 
  and 
  HCl. 
  

   Another 
  new 
  and 
  clean 
  pipette 
  was 
  used 
  to 
  remove 
  1 
  c.c. 
  of 
  

   the 
  well-shaken 
  mixture 
  and 
  to 
  transfer 
  it 
  to 
  a 
  second 
  flask 
  

   containing 
  99 
  c.c. 
  of 
  distilled 
  water 
  and 
  HCl. 
  More 
  dis- 
  

   tilled 
  water 
  was 
  added 
  to 
  each 
  flask, 
  and, 
  after 
  sealing, 
  the 
  

   contents 
  were 
  in 
  due 
  course 
  tested. 
  

  

  Divisions 
  per 
  minute. 
  

   Gram 
  radium. 
  Collected 
  over 
  water. 
  Over 
  mercury. 
  

  

  1-57x10-9 
  8-43 
  8-43 
  

  

  1-57x10-^1 
  -080 
  -083 
  

  

  The 
  agreement 
  is 
  better 
  than 
  can 
  be 
  expected 
  and 
  is 
  partly 
  

   accidental. 
  One 
  division 
  per 
  minute 
  of 
  the 
  electroscope 
  is 
  a 
  

   measure 
  of 
  the 
  emanation 
  from 
  1'90 
  x 
  lO'^*^ 
  gram 
  of 
  radium. 
  

   In 
  testing 
  the 
  specimens 
  of 
  sea-water 
  it 
  was 
  found 
  that 
  

   the 
  readings 
  by 
  day 
  were 
  larger 
  than 
  those 
  by 
  night. 
  Mr. 
  F. 
  

   W. 
  Bates 
  has 
  recently 
  proved 
  that 
  the 
  conduction 
  of 
  sulphur 
  

   is 
  greatly 
  increased 
  by 
  direct 
  sunlight, 
  and 
  also 
  to 
  a 
  less 
  

   extent 
  affected 
  by 
  daylight. 
  My 
  readings 
  were, 
  therefore, 
  

   taken 
  between 
  5 
  p.m. 
  and 
  9 
  a.m., 
  during 
  which 
  time 
  the 
  

   aluminium-leaf 
  moved 
  about 
  10 
  divisions 
  of 
  the 
  scale 
  in 
  the 
  

   eyepiece 
  of 
  the 
  observing 
  microscope. 
  When 
  samples 
  were 
  

   tested 
  at 
  intervals 
  of 
  less 
  than 
  a 
  month 
  the 
  necessary 
  cor- 
  

   rections 
  were 
  made 
  for 
  the 
  incomplete 
  growth 
  of 
  the 
  rndiura 
  

   emanation 
  in 
  the 
  flasks. 
  The 
  flask 
  containing 
  distilled 
  

   water 
  and 
  HCl 
  alone 
  gave 
  the 
  same 
  reading 
  as 
  the 
  " 
  natural 
  

   leak.*' 
  

  

  