﻿144 
  

  

  Prof. 
  J. 
  Joly 
  on 
  the 
  Distribution 
  of 
  

  

  rocks 
  passed 
  through 
  by 
  the 
  tunnel. 
  The 
  solutions 
  had 
  been 
  

   prepared 
  with 
  much 
  care 
  and 
  stringent 
  precautions 
  against 
  

   accidental 
  contamination 
  with 
  radioactive 
  materials. 
  After 
  

   each 
  radium 
  test 
  the 
  alkaline 
  and 
  acid 
  solutions 
  were 
  put 
  by 
  

   in 
  corked 
  bottles. 
  The 
  quantities 
  of 
  rock 
  in 
  solution 
  are, 
  

   indeed, 
  small 
  ; 
  in 
  most 
  cases 
  rather 
  less 
  than 
  10 
  grams. 
  

   Notwithstanding 
  this, 
  in 
  all 
  but 
  a 
  very 
  few 
  instances, 
  

   perfectly 
  definite 
  readings 
  of 
  the 
  increased 
  discharge 
  rate 
  

   due 
  to 
  the 
  contained 
  thorium 
  have 
  been 
  obtained. 
  The 
  

   alkaline 
  solutions 
  have 
  not 
  in 
  every 
  case 
  been 
  dealt 
  with. 
  

   About 
  one 
  third 
  of 
  the 
  entire 
  number 
  of 
  alkaline 
  solutions 
  

   were 
  investigated 
  for 
  thorium, 
  but 
  with 
  negative 
  results. 
  

   This 
  is 
  to 
  be 
  expected 
  from 
  the 
  limited 
  sensibility 
  of 
  the 
  

   method 
  of 
  observation 
  and 
  from 
  the 
  insolubility 
  of 
  both 
  the 
  

   carbonate 
  and 
  oxide 
  of 
  thorium, 
  a 
  property 
  which 
  must 
  result 
  

   in 
  the 
  retention 
  of 
  the 
  greater 
  part 
  of 
  the 
  thorium 
  in 
  the 
  

   residue 
  of 
  the 
  melt 
  after 
  this 
  is 
  leached 
  with 
  water. 
  In 
  one 
  

   case 
  only 
  was 
  any 
  appreciable 
  quantity 
  of 
  thorium 
  found 
  in 
  

   the 
  alkaline 
  solution. 
  In 
  this 
  case 
  a 
  very 
  abnormal 
  amount 
  

   of 
  radium 
  had 
  also 
  been 
  detected 
  in 
  the 
  alkaline 
  solution. 
  

  

  The 
  numbering 
  of 
  the 
  rocks 
  and 
  their 
  position 
  in 
  the 
  tunnel 
  

   are 
  taken 
  from 
  Stapff^s 
  great 
  work 
  on 
  the 
  St. 
  Gothard 
  Tunnel 
  

   (A^inecVe 
  Special 
  aux 
  Rapports 
  du 
  Conseil 
  Federal 
  Suisse 
  sur 
  

   la 
  Marche 
  de 
  UEntreprise 
  du 
  St. 
  -Gothard). 
  The 
  naming 
  of 
  

   the 
  rocks 
  is 
  based 
  on 
  Stapff's 
  nomenclature. 
  I 
  add 
  the 
  

   radium 
  determinations 
  for 
  comparison. 
  They 
  have 
  not 
  before 
  

   been 
  published 
  in 
  detail. 
  (Table, 
  p. 
  143.) 
  

  

  The 
  means 
  of 
  the 
  determinations 
  of 
  the 
  several 
  geological 
  

   divisions 
  into 
  which 
  Stapff 
  subdivides 
  the 
  course 
  of 
  the 
  tunnel 
  

   are 
  as 
  follows 
  : 
  — 
  

  

  

  Thorium 
  in 
  

  

  grams 
  per 
  

  

  gram 
  

  

  X 
  10-5. 
  

  

  Eadium 
  in 
  

  

  grams 
  per 
  

  

  gram 
  

  

  X 
  10-12. 
  

  

  Uranium 
  in 
  

  

  granjs 
  per 
  

  

  gram 
  

  

  X 
  io-«. 
  

  

  Granite 
  and 
  gneiss 
  of 
  Finsteraarhorn 
  Massif 
  . 
  

   Altered 
  sediments, 
  Ursernmulde 
  

  

  1-85 
  

   0-97 
  

   1-18 
  

   0-51 
  

  

  7-7 
  

   4-9 
  

   3-9 
  

   3-4 
  

  

  2-26 
  

   1-44 
  

   1-15 
  

   1-00 
  

  

  Schists, 
  etc. 
  of 
  St. 
  Gothai'd 
  Massif 
  

  

  Altered 
  sediments, 
  Tessinm 
  ulde 
  

  

  

  The 
  uranium 
  is 
  computed 
  on 
  Boltwood's 
  measurement 
  of 
  

   the 
  equilibrium 
  amount 
  of 
  radium 
  in 
  one 
  gram 
  of 
  uranium 
  : 
  

   0-4 
  X 
  10~^ 
  gram. 
  

  

  In 
  my 
  address, 
  referred 
  to 
  above, 
  I 
  drew 
  attention 
  to 
  a 
  

   cori^espoudence 
  between 
  the 
  radium 
  content 
  of 
  the 
  St. 
  Gothard 
  

  

  