﻿Radium- 
  Content 
  of 
  Sea 
  Water. 
  399 
  

  

  observed 
  about 
  15 
  minutes 
  after 
  the 
  introduction 
  of 
  the 
  

   emanation 
  and 
  again 
  in 
  three 
  hours. 
  The 
  characteristic 
  gain 
  

   in 
  rate 
  is 
  an 
  assurance 
  that 
  the 
  effect 
  was 
  indeed 
  due 
  to 
  

   radium 
  and 
  not 
  to 
  any 
  loss 
  of 
  insulation, 
  &c. 
  The 
  constant 
  

   of 
  the 
  electroscopes 
  was 
  from 
  0'5 
  to 
  0*7 
  : 
  in 
  other 
  words 
  this 
  

   was 
  the 
  radium-value 
  in 
  billionths 
  of 
  a 
  gram 
  for 
  a 
  gain 
  of 
  

   one 
  scale-division 
  per 
  hour. 
  It 
  will 
  be 
  seen 
  that 
  working 
  

   with 
  so 
  low 
  a 
  constant 
  resulted 
  in 
  quite 
  unmistakable 
  incre- 
  

   ments 
  of 
  rate 
  even 
  in 
  the 
  case 
  of 
  the 
  lowest 
  values 
  obtained. 
  

   Ebullition 
  is 
  in 
  every 
  case 
  carried 
  on 
  under 
  reduced 
  pressure 
  

   and 
  for 
  from 
  fifty 
  minutes 
  to 
  one 
  hour. 
  A 
  quantity 
  of 
  

   powdered 
  talc 
  (tested 
  for 
  radium) 
  averaging 
  50 
  milligrams 
  

   is 
  added 
  to 
  improve 
  the 
  ebullition. 
  

  

  With 
  regard 
  to 
  the 
  nature 
  of 
  the 
  bottles 
  in 
  which 
  the 
  

   water 
  was 
  collected, 
  their 
  proper 
  cleansing, 
  and 
  the 
  time 
  in 
  

   which 
  the 
  water 
  was 
  retained 
  in 
  them. 
  In 
  the 
  case 
  of 
  

   experiments 
  (20)-(24) 
  the 
  bottles 
  were 
  new, 
  of 
  white 
  glass, 
  

   and 
  stoppered. 
  They 
  were 
  carefully 
  washed 
  and 
  were 
  filled 
  

   from 
  the 
  canvas 
  buckets. 
  The 
  water 
  was 
  stored 
  in 
  them 
  for 
  

   periods 
  varying 
  from 
  six 
  weeks 
  downwards, 
  according 
  as 
  the 
  

   homeward 
  journey 
  of 
  the 
  friend 
  who 
  acted 
  for 
  me 
  was 
  

   accomplished. 
  The 
  bottles 
  for 
  (15) 
  and 
  (16) 
  were 
  supplied, 
  

   and 
  specially 
  washed, 
  by 
  me. 
  xnTo 
  pains 
  Avere 
  spared 
  in 
  their 
  

   thorough 
  cleansing. 
  A 
  third, 
  similar 
  bottle, 
  was 
  sent 
  out 
  on 
  

   the 
  same 
  voyage. 
  This 
  brought 
  back 
  water 
  from 
  the 
  Rio 
  de 
  

   la 
  Plata. 
  The 
  three 
  bottles 
  were 
  in 
  appearance 
  alike, 
  and 
  

   were 
  new, 
  closed 
  with 
  rubber 
  stoppers. 
  The 
  collector 
  in 
  this 
  

   case 
  was 
  a 
  gentleman 
  of 
  considerable 
  scientific 
  training 
  who 
  

   quite 
  understood 
  the 
  importance 
  of 
  care 
  in 
  guarding 
  against 
  

   contamination. 
  Owing 
  to 
  some 
  negligence 
  in 
  their 
  delivery 
  

   they 
  did 
  not 
  reach 
  me 
  till 
  about 
  three 
  months 
  after 
  they 
  were 
  

   filled. 
  Sample 
  (25) 
  was 
  also 
  in 
  a 
  bottle 
  supplied 
  and 
  washed 
  

   by 
  me. 
  It 
  reached 
  me 
  in 
  a 
  few 
  hours 
  after 
  filling. 
  In 
  all 
  

   the 
  other 
  cases 
  the 
  bottles 
  were 
  purchased 
  by 
  the 
  collectors 
  

   or 
  supplied 
  on 
  board 
  ship. 
  I 
  have 
  received 
  every 
  assurance 
  

   as 
  to 
  the 
  precautions 
  taken 
  in 
  obtaining 
  these 
  samples. 
  The 
  

   Atlantic 
  series 
  were 
  in 
  black 
  glass 
  bottles. 
  The 
  water 
  

   was 
  enclosed 
  for 
  from 
  twelve 
  to 
  five 
  or 
  six 
  days 
  before 
  

   reaching 
  me. 
  

  

  The 
  details 
  of 
  the 
  experiments 
  are 
  contained 
  in 
  the 
  table 
  

   which 
  follows. 
  Owing 
  to 
  the 
  method 
  adopted 
  in 
  boiling 
  off 
  

   the 
  emanation 
  about 
  200 
  ccs. 
  of 
  distilled 
  water 
  are 
  added 
  

   upon 
  each 
  experiment 
  (to 
  expel 
  all 
  residual 
  gas 
  from 
  the 
  

   flask), 
  and, 
  hence, 
  between 
  each 
  experiment 
  this 
  is 
  again 
  

   removed 
  by 
  evaporation. 
  

  

  