﻿Chemistry 
  and 
  Physics. 
  145 
  

  

  But 
  it 
  should 
  be 
  noted 
  that 
  the 
  radio-activity 
  of 
  all 
  these 
  frac- 
  

   tions, 
  whether 
  produced 
  by 
  crystallization 
  as 
  in 
  the 
  case 
  of 
  the 
  

   chloride 
  or 
  by 
  precipitation 
  as 
  in 
  that 
  of 
  the 
  sulphate 
  and 
  carbo- 
  

   nate, 
  increases 
  very 
  rapidly 
  for 
  several 
  days 
  after 
  assuming 
  the 
  

   solid 
  form 
  ; 
  attaining 
  at 
  the 
  end 
  of 
  some 
  weeks 
  in 
  the 
  case 
  of 
  the 
  

   very 
  active 
  fractions 
  a 
  limiting 
  value 
  which 
  may 
  reach 
  even 
  five 
  

   or 
  six 
  times 
  the 
  initial 
  one. 
  Experiments 
  have 
  not 
  yet 
  been 
  

   made 
  to 
  fix 
  the 
  atomic 
  mass 
  of 
  the 
  substance 
  used 
  by 
  Demarcay 
  — 
  

   which 
  was 
  17000 
  times 
  more 
  active 
  than 
  uranium 
  — 
  for 
  want 
  of 
  

   material. 
  Evidently 
  the 
  atomic 
  mass 
  of 
  radium 
  is 
  higher 
  than 
  

   that 
  of 
  barium. 
  — 
  C. 
  7?., 
  cxxix, 
  760, 
  November, 
  1899. 
  g. 
  f. 
  b. 
  

  

  4. 
  On 
  Chemical 
  Effects 
  produced 
  by 
  Becquerel 
  Rays. 
  — 
  A 
  yet 
  

   more 
  remarkable 
  effect 
  of 
  the 
  Becquerel 
  rays 
  has 
  been 
  noticed 
  by 
  

   M. 
  and 
  Mme. 
  Curie. 
  They 
  find 
  that 
  these 
  rays 
  emitted 
  by 
  very 
  

   strongly 
  radio-active 
  barium 
  salts 
  are 
  capable 
  of 
  transforming 
  

   oxygen 
  into 
  ozone. 
  When 
  such 
  a 
  salt 
  is 
  preserved 
  in 
  a 
  stoppered 
  

   bottle, 
  for 
  a 
  short 
  time, 
  there 
  is 
  perceived 
  on 
  opening 
  the 
  bottle 
  a 
  

   distinct 
  odor 
  of 
  ozone; 
  a 
  fact 
  first 
  noted 
  by 
  Demarcay 
  with 
  the 
  

   sample 
  of 
  active 
  barium 
  chloride 
  sent 
  him 
  for 
  his 
  spectroscopic 
  

   work. 
  With 
  the 
  bottle 
  open 
  the 
  odor 
  is 
  dissipated 
  almost 
  com- 
  

   pletely. 
  But 
  if 
  the 
  bottle 
  be 
  closed 
  it 
  regains 
  its 
  primitive 
  intens- 
  

   ity 
  in 
  ten 
  or 
  fifteen 
  minutes. 
  The 
  production 
  of 
  ozone 
  in 
  this 
  

   way 
  was 
  verified 
  by 
  the 
  authors 
  by 
  means 
  of 
  iodide 
  of 
  starch 
  

   paper 
  which, 
  placed 
  before 
  the 
  mouth 
  of 
  the 
  bottle, 
  was 
  distinctly 
  

   colored. 
  The 
  tint 
  is 
  darker 
  if 
  the 
  active 
  substance 
  is 
  placed 
  

   directly 
  on 
  the 
  paper. 
  Ordinary 
  barium 
  chloride 
  produces 
  no 
  

   effect 
  under 
  these 
  conditions. 
  The 
  radio-active 
  substances 
  required 
  

   to 
  produce 
  this 
  ozonizing 
  effect 
  are 
  all 
  very 
  active 
  and 
  very 
  lumi- 
  

   nous. 
  But 
  the 
  effect 
  seems 
  more 
  directly 
  connected 
  with 
  the 
  

   radio-activity 
  than 
  with 
  the 
  luminosity 
  ; 
  a 
  radium 
  carbonate, 
  

   though 
  very 
  luminous, 
  producing 
  less 
  ozone 
  than 
  a 
  radium 
  chlor- 
  

   ide, 
  much 
  less 
  luminous 
  though 
  more 
  strongly 
  radio-active. 
  An 
  

   analogous 
  action 
  of 
  the 
  Becquerel 
  rays 
  upon 
  glass 
  has 
  also 
  been 
  

   observed 
  by 
  the 
  authors. 
  If 
  a 
  sample 
  of 
  a 
  radium 
  salt 
  be 
  pre- 
  

   served 
  for 
  a 
  long 
  time 
  in 
  a 
  stoppered 
  bottle, 
  a 
  violet 
  coloration 
  

   appears 
  inside 
  the 
  glass 
  and 
  passes 
  gradually 
  through 
  to 
  the 
  out- 
  

   side. 
  With 
  a 
  very 
  active 
  material, 
  the 
  bottom 
  of 
  the 
  bottle 
  

   appears 
  almost 
  black 
  in 
  the 
  course 
  of 
  twelve 
  days. 
  Even 
  barium 
  

   platinocyanide, 
  when 
  exposed 
  to 
  the 
  action 
  of 
  radium, 
  begins 
  to 
  

   turn 
  first 
  yellow 
  and 
  then 
  brown, 
  losing 
  its 
  power 
  of 
  phospho- 
  

   rescence 
  ; 
  though 
  by 
  exposure 
  to 
  sunlight 
  this 
  power 
  may 
  be 
  

   recovered. 
  This 
  yellowing 
  effect 
  can 
  take 
  place 
  even 
  through 
  a 
  

   plate 
  of 
  aluminum. 
  If 
  such 
  a 
  plate 
  covered 
  with 
  the 
  platino- 
  

   cyanide 
  be 
  placed 
  above 
  a 
  radio-active 
  salt, 
  in 
  the 
  dark, 
  the 
  

   platinocyanide 
  phosphoresces 
  at 
  first 
  strongly, 
  but 
  gradually 
  

   becomes 
  brown 
  and 
  loses 
  its 
  brightness. 
  But 
  now 
  if 
  it 
  be 
  

   exposed 
  to 
  light 
  the 
  platinocyanide 
  is 
  partially 
  regenerated, 
  so 
  

   that 
  it 
  now 
  shines 
  in 
  the 
  dark 
  ; 
  thus 
  showing 
  the 
  synthesis 
  of 
  a 
  

   phosphorescent 
  body 
  of 
  long 
  duration 
  by 
  means 
  of 
  a 
  fluorescent 
  

   body 
  and 
  a 
  radio 
  active 
  one. 
  Even 
  crystals 
  of 
  the 
  radiobarium 
  

  

  