﻿144 
  Scientific 
  Intelligence. 
  

  

  and 
  of 
  certain 
  impurities, 
  such 
  as 
  calcium 
  and 
  lead, 
  the 
  lines 
  

   being 
  very 
  weak; 
  and 
  (3) 
  fifteen 
  new 
  lines 
  belonging 
  to 
  radium, 
  

   some 
  of 
  which 
  are 
  as 
  strong 
  as 
  the 
  brightest 
  barium-lines. 
  These 
  

   lines 
  have 
  the 
  following 
  wave 
  lengths, 
  the 
  numbers 
  appended 
  

   being 
  the 
  intensities, 
  16 
  being 
  the 
  brightest 
  and 
  1 
  the 
  feeblest 
  : 
  

   4826*3 
  (10), 
  4726*9 
  (5), 
  4699"8 
  (3), 
  4692'1 
  (7), 
  4683-0 
  (14), 
  4641-9 
  

   (4), 
  4627-4 
  about, 
  (4), 
  4600-3 
  (3), 
  4533'5 
  (9), 
  4458*0 
  about, 
  (3), 
  

   4436-1 
  (8), 
  4364-2 
  (3), 
  4340'6 
  (12), 
  3814-7 
  (16), 
  3649*6 
  (12). 
  At 
  

   4627-4 
  and 
  4458*0 
  are 
  the 
  centers 
  of 
  nebulous 
  bands, 
  the 
  latter 
  

   being 
  the 
  weaker. 
  The 
  lines 
  are 
  sharp 
  and 
  fine 
  and 
  recall 
  those 
  

   of 
  barium. 
  Other 
  lines 
  were 
  observed, 
  a 
  dozen 
  or 
  more 
  in 
  num- 
  

   ber, 
  but 
  very 
  faint. 
  They 
  will 
  be 
  measured 
  when 
  the 
  radium 
  is 
  

   further 
  purified. 
  The 
  author 
  is 
  now 
  examining 
  the 
  less 
  refrangi- 
  

   ble 
  region. 
  — 
  C.H., 
  cxxix, 
  716, 
  November, 
  1899. 
  g. 
  f. 
  b. 
  

  

  3. 
  On 
  the 
  Atomic 
  Mass 
  of 
  Radio-active 
  Barium 
  Chloride. 
  — 
  

   Experiments 
  have 
  been 
  made 
  by 
  Mme. 
  Curie 
  to 
  determine 
  the 
  

   atomic 
  mass 
  of 
  the 
  metal 
  existing 
  in 
  the 
  successive 
  products 
  of 
  

   purification 
  of 
  the 
  radio-active 
  barium 
  chloride. 
  Two 
  kilograms 
  

   of 
  this 
  active 
  chloride, 
  extracted 
  from 
  half 
  a 
  ton 
  of 
  uranium 
  

   residues 
  were 
  submitted 
  to 
  fractional 
  crystallization, 
  the 
  activity 
  

   being 
  concentrated 
  in 
  the 
  least 
  soluble 
  fractions. 
  The 
  chloride 
  

   thus 
  obtained 
  was 
  fractionally 
  precipitated 
  with 
  alcohol. 
  The 
  

   most 
  active 
  material 
  was 
  contained 
  in 
  the 
  precipitated 
  portions. 
  

   The 
  atomic 
  mass 
  was 
  determined 
  in 
  the 
  anhydrous 
  chloride 
  in 
  

   the 
  usual 
  way 
  by 
  precipitating 
  the 
  chlorine 
  with 
  silver 
  nitrate. 
  

   Each 
  of 
  these 
  determinations 
  was 
  accompanied 
  by 
  a 
  similar 
  de- 
  

   termination 
  on 
  inactive 
  chloride, 
  as 
  a 
  control. 
  The 
  radio-activity 
  

   was 
  simultaneously 
  determined 
  by 
  measuring 
  the 
  current 
  flowing 
  

   between 
  the 
  two 
  plates 
  of 
  a 
  condenser 
  8 
  cm 
  in 
  diameter 
  placed 
  3 
  cm 
  

   apart, 
  the 
  differences 
  of 
  potential 
  between 
  these 
  plates 
  being 
  100 
  

   volts. 
  The 
  active 
  material 
  occupied 
  a 
  circular 
  space 
  2 
  cm 
  in 
  diam- 
  

   eter 
  on 
  the 
  lower 
  plate. 
  The 
  current 
  produced 
  by 
  metallic 
  ura- 
  

   nium 
  under 
  these 
  conditions 
  is 
  0-25 
  X 
  10 
  -11 
  ampere. 
  With 
  the 
  suc- 
  

   cessive 
  fractions 
  the 
  following 
  values 
  were 
  obtained 
  : 
  

  

  ix 
  10— 
  u 
  amperes 
  a 
  m 
  Ba 
  

  

  750 
  3000 
  140-0 
  138-1 
  

  

  1170 
  4700 
  140-9 
  137-6 
  

  

  1870 
  7500 
  145-8 
  137-8 
  

  

  Here 
  i 
  represents 
  the 
  current 
  passing, 
  a 
  the 
  radio-activity 
  thus 
  

   measured 
  in 
  terms 
  of 
  uranium 
  taken 
  as 
  unity, 
  m 
  the 
  atomic 
  mass 
  

   of 
  the 
  metal 
  in 
  the 
  active 
  chloride 
  and 
  Ba 
  that 
  of 
  the 
  metal 
  in 
  

   the 
  inactive 
  chloride 
  used 
  for 
  comparison. 
  It 
  will 
  be 
  observed 
  

   that 
  a 
  notable 
  difference 
  exists 
  between 
  the 
  atomic 
  mass 
  of 
  the 
  

   active 
  chloride 
  and 
  that 
  of 
  the 
  ordinary 
  chloride 
  ; 
  and 
  further 
  

   that 
  as 
  the 
  radio-activity 
  increases, 
  the 
  atomic 
  mass 
  becomes 
  

   greater 
  also. 
  Taken 
  in 
  connection 
  with 
  the 
  spectrum 
  results 
  

   obtained 
  by 
  Demarcay 
  as 
  given 
  above, 
  it 
  would 
  seem 
  that 
  radium 
  

   has 
  a 
  right 
  to 
  recognition 
  as 
  an 
  element. 
  The 
  substances 
  above 
  

   measured 
  were 
  fractions 
  examined 
  at 
  once 
  after 
  their 
  preparation. 
  

  

  