﻿On 
  tJie 
  Radioactivity 
  of 
  certain 
  Lavas. 
  577 
  

  

  the 
  fundamental 
  assumptions 
  connected 
  with 
  the 
  diffusion 
  

   conceptions 
  of 
  Nernst, 
  Brunner, 
  and 
  others, 
  have 
  no 
  theoretical 
  

   and 
  no 
  experimental 
  support 
  whatever. 
  I 
  have 
  traversed 
  in 
  

   this 
  first 
  publication 
  almost 
  all 
  the 
  experimental 
  material 
  of 
  

   Bruner 
  and 
  Tolloczko, 
  Nernst 
  and 
  Brunner, 
  so 
  far 
  as 
  it 
  deals 
  

   with 
  molecular 
  reactions 
  in 
  solution. 
  I 
  have 
  shown 
  step 
  by 
  

   step, 
  that 
  all 
  their 
  experimental 
  proofs 
  here 
  are 
  nothing 
  but 
  

   arbitrary 
  experiments, 
  that 
  as 
  soon 
  as 
  they 
  are 
  replaced 
  by 
  

   accurate 
  reliable 
  results 
  the 
  very 
  same 
  substances 
  furnish 
  us 
  

   with 
  a 
  solid 
  proof 
  against 
  the 
  diffusion 
  theory. 
  In 
  my 
  next 
  

   publication 
  I 
  will 
  deal 
  with 
  the 
  speed 
  of 
  chemical 
  reaction 
  in 
  

   heterogeneous 
  systems, 
  and 
  T 
  shall 
  have 
  then 
  a 
  still 
  wider 
  

   opportunity 
  to 
  show, 
  traversing 
  again 
  the 
  whole 
  of 
  the 
  

   experimental 
  material 
  of 
  Nernst 
  and 
  Brunner, 
  that 
  from 
  the 
  

   beginning 
  to 
  the 
  end 
  there 
  is 
  not 
  one 
  experiment 
  which 
  is 
  

   not 
  arbitrary, 
  and 
  which, 
  when 
  replaced 
  by 
  correct 
  results, 
  

   does 
  not 
  most 
  decidedly 
  refute 
  the 
  so-called 
  diffusion 
  theory 
  

   with 
  all 
  its 
  numerous 
  and 
  unnatural 
  assumptions. 
  It 
  is 
  a 
  

   theory, 
  which 
  is 
  neither 
  theoretically 
  sound, 
  nor 
  is 
  it 
  supported 
  

   in 
  the 
  least 
  degree 
  by 
  direct 
  experiment. 
  

  

  Davy-Faraday 
  Laboratory 
  

   of 
  tlie 
  Koval 
  Institution, 
  London, 
  \ 
  \ 
  

  

  January 
  1909. 
  \ 
  ' 
  

  

  LXII. 
  On 
  the 
  Radioactivitij 
  of 
  certain 
  Lavas. 
  

   By 
  J. 
  JoLY, 
  F.R.S.'' 
  

  

  SOME 
  months 
  ago, 
  when 
  determining 
  the 
  radium 
  content 
  

   of 
  lavas 
  from 
  various 
  parts 
  of 
  the 
  world, 
  I 
  noticed 
  with 
  

   surprise 
  the 
  relatively 
  large 
  amount 
  of 
  radium 
  contained 
  in 
  

   one 
  from 
  V^esuvius. 
  This 
  lava 
  was 
  from 
  the 
  eruptiou 
  of 
  

   1855. 
  The 
  reading 
  was 
  so 
  high 
  that 
  before 
  accepting 
  it 
  I 
  

   re-determined 
  it 
  upon 
  a 
  second 
  chip 
  taken 
  from 
  the 
  interior 
  

   of 
  the 
  same 
  hand 
  specimen. 
  I 
  obtained 
  identically 
  the 
  same 
  

   value. 
  

  

  Returning 
  to 
  the 
  subject 
  at 
  a 
  more 
  recent 
  date 
  I 
  examined 
  

   the 
  series 
  of 
  dated 
  Vesuvian 
  lavas 
  in 
  the 
  Museum 
  of 
  Geology 
  

   in 
  Trinity 
  College, 
  and 
  found 
  quantities 
  of 
  radium 
  in 
  every 
  

   case 
  supporting 
  my 
  original 
  determination. 
  But 
  the 
  fact 
  

   seemed 
  brought 
  out 
  that 
  the 
  earlier 
  lavas 
  of 
  the 
  last 
  three 
  

   hundred 
  years 
  possessed 
  a 
  low^er 
  radium 
  content 
  than 
  the 
  

   more 
  recently 
  ejected 
  rocks. 
  At 
  this 
  stage 
  Prof. 
  Johnston- 
  

   Lavis 
  was 
  so 
  kind 
  as 
  to 
  send 
  me 
  some 
  samples 
  of 
  the 
  lava- 
  

   ilow 
  of 
  April 
  1906. 
  Subsequently 
  he 
  also 
  supplied 
  me 
  with 
  

   one 
  of 
  the 
  oldest 
  lavas 
  : 
  what 
  he 
  has 
  classified 
  as 
  Dyke 
  No. 
  1 
  

   of 
  the 
  ancient 
  volcano 
  of 
  Monte 
  Somma. 
  This 
  last 
  rock 
  is 
  — 
  

   * 
  Communicated 
  bv 
  the 
  Author 
  . 
  

  

  