﻿1^6 
  Scientific 
  Intelligence. 
  

  

  SCIENTIFIC 
  INTELLIGENCE. 
  

   I. 
  Chemistry 
  axd 
  Physics. 
  

  

  1. 
  A 
  New 
  Photographic 
  Phenomenon: 
  — 
  D. 
  N. 
  McArthur 
  

   and 
  A. 
  W. 
  Stewart 
  have 
  made 
  an 
  interesting 
  observation. 
  A 
  

   sensitive 
  photographic 
  plate 
  is 
  placed, 
  film 
  upward, 
  at 
  the 
  bot- 
  

   tom 
  of 
  a 
  light-tight 
  box 
  of 
  wood 
  or 
  cardboard; 
  on 
  the 
  film 
  are 
  

   placed 
  two 
  or 
  more 
  glass 
  microscopic 
  slides, 
  and 
  resting 
  on 
  these 
  

   supports 
  is 
  laid 
  a 
  negative, 
  also 
  film 
  side 
  upward. 
  The 
  box 
  is 
  

   then 
  closed 
  and 
  placed 
  in 
  the 
  neighborhood 
  of 
  a 
  Bunsen 
  burner, 
  

   a 
  bat's- 
  wing 
  flame, 
  or 
  an 
  electrical 
  kettle-heater. 
  After 
  an 
  

   exposure 
  of 
  some 
  hours, 
  the 
  plate 
  after 
  development 
  shows 
  an 
  

   image 
  of 
  the 
  negative, 
  but 
  reversed 
  in 
  the 
  form 
  of 
  a 
  positive. 
  

   Care 
  was 
  taken 
  that 
  no 
  light 
  entered 
  the 
  box, 
  and 
  certain 
  of 
  the 
  

   experiments 
  were 
  conducted 
  in 
  total 
  darkness. 
  The 
  results 
  were 
  

   obtained 
  either 
  when 
  the 
  box 
  was 
  left 
  in 
  the 
  open 
  air 
  or 
  was 
  

   enclosed 
  in 
  an 
  air-tight 
  desiccator. 
  The 
  source 
  of 
  heat 
  appeared 
  

   to 
  exercise 
  some 
  influence 
  upon 
  the 
  rapidity 
  of 
  the 
  action. 
  A 
  

   Meker 
  burner 
  gave 
  very 
  poor 
  results. 
  Poor 
  results 
  were 
  given 
  

   by 
  a 
  Bunsen 
  flame 
  impregnated 
  with 
  calcium 
  salts, 
  while 
  with 
  

   sodium 
  and 
  lithium 
  salts 
  the 
  effects 
  were 
  more 
  strongly 
  marked. 
  

   The 
  electric 
  heater 
  gave 
  good 
  results 
  when 
  worked 
  on 
  its 
  lower 
  

   resistance. 
  The 
  distance 
  between 
  the 
  box 
  and 
  the 
  source 
  of 
  

   heat 
  was 
  usually 
  about 
  30-45 
  cm., 
  but 
  on 
  one 
  occasion 
  results 
  

   were 
  obtained 
  with 
  a 
  box 
  placed 
  in 
  a 
  cupboard 
  180 
  cm. 
  away 
  

   from 
  a 
  sodium 
  burner, 
  although 
  in 
  this 
  case 
  the 
  exposure 
  was 
  

   an 
  extremely 
  prolonged 
  one. 
  

  

  A 
  striking 
  peculiarity 
  of 
  these 
  experiments 
  was 
  the 
  fact 
  that 
  

   when 
  the 
  box 
  was 
  so 
  arranged 
  that 
  the 
  sensitive 
  plate 
  lay 
  

   between 
  the 
  source 
  of 
  heat 
  and 
  the 
  negative, 
  the 
  results 
  were 
  

   obtained 
  just 
  as 
  sharply 
  as 
  with 
  the 
  reverse 
  arrangement, 
  and 
  

   the 
  authors 
  believe 
  that 
  were 
  direct-acting 
  rays 
  concerned 
  in 
  

   the 
  matter 
  the 
  plate 
  would 
  have 
  been 
  fogged 
  by 
  their 
  passage 
  

   through 
  it 
  before 
  they 
  reached 
  the 
  negative. 
  It 
  was 
  shown 
  that 
  

   the 
  results 
  were 
  not 
  due 
  to 
  radioactive 
  material 
  in 
  the 
  neighbor- 
  

   hood 
  and 
  that 
  they 
  were 
  not 
  due 
  to 
  light 
  stored 
  up 
  by 
  the 
  nega- 
  

   tive. 
  The 
  rays 
  which 
  produce 
  the 
  effects 
  are 
  similar 
  to 
  light 
  

   rays 
  in 
  passing 
  through 
  glass 
  and 
  in 
  being 
  similarly 
  refracted 
  

   and 
  diffracted. 
  The 
  phenomenon 
  has 
  not 
  yet 
  been 
  entirely 
  elu- 
  

   cidated, 
  but 
  an 
  interesting 
  field 
  has 
  been 
  opened 
  up 
  which 
  is 
  

   being 
  further 
  investigated. 
  — 
  Jour. 
  Chem. 
  Soc., 
  115, 
  973. 
  

  

  2. 
  The 
  Analytical 
  Chemistry 
  of 
  Uranium. 
  — 
  C. 
  A. 
  Pierle 
  has 
  

   found 
  that 
  the 
  well-known 
  method 
  of 
  precipitating 
  ammonium 
  

   uranate 
  by 
  means 
  of 
  ammonium 
  hydroxide 
  and 
  igniting 
  to 
  U 
  3 
  8 
  

   gives 
  excellent 
  results. 
  He 
  obtained 
  nearly 
  as 
  good 
  results 
  by 
  

   precipitation 
  with 
  dehydrogen 
  ammonium 
  phosphate 
  and 
  ignit- 
  

  

  