﻿Chemistry 
  and 
  Physics. 
  469 
  

  

  they 
  are 
  spectra 
  of 
  different 
  gases. 
  These 
  spectra 
  may 
  be 
  pro- 
  

   duced 
  by 
  different 
  vibrations 
  of 
  the 
  oxygen 
  molecule, 
  or 
  they 
  

   may 
  be 
  the 
  spectra 
  of 
  two 
  different 
  modifications 
  of 
  oxygen, 
  or 
  

   the 
  spectra 
  of 
  two 
  distinct 
  gases 
  resulting 
  from 
  a 
  dissociation 
  of 
  

   oxygen. 
  In 
  order 
  to 
  test 
  the 
  last 
  hypothesis, 
  oxygen 
  was 
  sparked 
  

   in 
  an 
  apparatus 
  with 
  hollow 
  platinum 
  electrodes, 
  connected 
  with 
  

   a 
  Sprengel 
  pump. 
  The 
  distance 
  between 
  the 
  electrodes 
  was 
  35 
  mra 
  

   and 
  the 
  highest 
  pressure 
  consistent 
  with 
  the 
  production 
  of 
  the 
  

   two 
  spectra 
  was 
  initially 
  employed, 
  being 
  380 
  mm 
  . 
  The 
  fractions 
  

   of 
  the 
  gas 
  obtained 
  from 
  the 
  anode 
  and 
  kathode 
  were 
  weighed 
  

   and 
  compared 
  with 
  the 
  oxygen 
  before 
  sparking. 
  With 
  long 
  

   sparks 
  a 
  lighter 
  fraction 
  was 
  obtained 
  at 
  the 
  kathode 
  and 
  with 
  

   short 
  sparks 
  a 
  heavier 
  fraction. 
  With 
  long 
  sparks 
  the 
  density 
  of 
  

   the 
  kathode 
  oxygen 
  was 
  15-78, 
  15*79, 
  15-80, 
  15*79; 
  with 
  short 
  

   sparks 
  16*00, 
  16*01, 
  16*02, 
  16*04, 
  16*06, 
  16*05. 
  The 
  density 
  of 
  the 
  

   unsparked 
  oxygen 
  was 
  15*88, 
  15*87, 
  15*89, 
  15*88, 
  15*88. 
  The 
  

   fractions 
  from 
  the 
  anode 
  showed 
  a 
  difference 
  in 
  the 
  same 
  direc- 
  

   tion, 
  though 
  not 
  as 
  definite. 
  Further 
  results 
  are 
  promised. 
  — 
  

   Nature, 
  li, 
  550, 
  April, 
  1895. 
  g. 
  f. 
  b. 
  

  

  5. 
  Krafte 
  der 
  Chemischen 
  Dynamih 
  ; 
  3 
  Vortrage 
  von 
  Dr. 
  Lud- 
  

   wig 
  Stettexheiueb. 
  8vo, 
  pp. 
  88. 
  Frankfurt-a-M. 
  1895. 
  (H. 
  

   Bechhold.) 
  — 
  These 
  lectures 
  appear 
  to 
  be 
  aimed 
  against 
  the 
  molec- 
  

   ular 
  constitution 
  of 
  matter, 
  every 
  substance 
  being 
  regarded 
  as 
  

   homogeneous 
  and 
  its 
  atoms 
  interacting 
  mechanically 
  with 
  all 
  

   other 
  atoms. 
  The 
  reasoning 
  seems 
  to 
  be 
  loose 
  and 
  the 
  conclusions 
  

   altogether 
  hypothetical. 
  g. 
  f. 
  b. 
  

  

  6. 
  Physical 
  Constants 
  of 
  Hydrogen. 
  — 
  Professor 
  Ramsay 
  has 
  

   received 
  a 
  letter 
  from 
  Professor 
  Olszewski 
  in 
  which 
  he 
  says 
  : 
  

   "I 
  have 
  at 
  last 
  succeeded 
  in 
  determining 
  the 
  critical 
  tempera- 
  

   ture 
  and 
  the 
  boiling 
  point 
  of 
  hydrogen. 
  I 
  have 
  found 
  for 
  the 
  

   former 
  —233° 
  and 
  for 
  the 
  latter 
  —243°. 
  I 
  have 
  used 
  the 
  dynam- 
  

   ical 
  method 
  which 
  I 
  described 
  in 
  the 
  Phil. 
  Mag. 
  A 
  thermal 
  

   couple 
  proved 
  of 
  no 
  use 
  and 
  I 
  was 
  obliged 
  to 
  avail 
  myself 
  of 
  a 
  

   platinum 
  wire 
  thermometer, 
  measuring 
  the 
  temperatures 
  by 
  the 
  

   alteration 
  in 
  resistance 
  of 
  the 
  wire. 
  I 
  have 
  obtained 
  satisfactory 
  

   results 
  and 
  intend 
  to 
  publish 
  an 
  account 
  of 
  them 
  in 
  English. 
  — 
  

   Nature, 
  March 
  21, 
  1895. 
  j. 
  t. 
  

  

  7. 
  Color 
  Photography. 
  — 
  At 
  a 
  meeting 
  of 
  the 
  Physical 
  Society 
  

   in 
  Berlin, 
  Feb. 
  8, 
  Dr. 
  Neuhaus 
  exhibited 
  a 
  series 
  of 
  color 
  photo- 
  

   graph's 
  taken 
  by 
  Lippmann's 
  method 
  with 
  prolonged 
  exposure. 
  

   Spectra 
  show, 
  if 
  the 
  exposure 
  is 
  sufficiently 
  long, 
  a 
  greenish 
  band 
  

   in 
  the 
  infra 
  red 
  as 
  well 
  as 
  in 
  the 
  ultra 
  violet, 
  in 
  addition 
  to 
  ordi- 
  

   nary 
  colors. 
  The 
  colored 
  band 
  was 
  very 
  markedly 
  displaced 
  by 
  

   both 
  over 
  and 
  under 
  exposure. 
  The 
  photographs 
  of 
  objects 
  with 
  

   mixed 
  colors, 
  such 
  as 
  fruits, 
  flowers, 
  butterflies, 
  etc., 
  were 
  good 
  : 
  

   but 
  their 
  production 
  was 
  extremely 
  difficult 
  and 
  only 
  one 
  plate 
  

   in 
  twenty-five 
  was, 
  on 
  an 
  average, 
  successful. 
  It 
  was 
  iound 
  easier 
  

   to 
  photograph 
  naturally 
  mixed 
  than 
  artificially 
  mixed 
  colors. 
  

   Some 
  substance 
  such 
  as 
  eosin 
  or 
  cyanin 
  must 
  be 
  added 
  to 
  the 
  

   films 
  to 
  make 
  them 
  more 
  sensitive 
  to 
  red 
  rays 
  and 
  less 
  sensitive 
  

  

  