﻿Chemistry 
  and 
  Physics. 
  413 
  

  

  annealing 
  temperature 
  a 
  glass 
  has 
  become 
  sufficiently 
  hard 
  to 
  

   withstand 
  very 
  great 
  local 
  pressure 
  for 
  short 
  periods 
  without 
  

   sensible 
  deformation." 
  

  

  By 
  taking 
  suitable 
  precautions 
  in 
  regulating 
  the 
  temperature 
  of 
  

   an 
  electric 
  furnace 
  the 
  experimenters 
  have 
  succeeded 
  in 
  making- 
  

   perfect 
  cells 
  of 
  the 
  type 
  involved 
  in 
  the 
  Rayleigh 
  interference- 
  

   refractometer. 
  The 
  inner 
  opposing 
  walls 
  were 
  as 
  plane 
  and 
  

   parallel 
  as 
  the 
  outer 
  surfaces 
  of 
  the 
  cell 
  windows. 
  The 
  parts 
  of 
  

   a 
  polarimeter 
  tube 
  of 
  soda-lime 
  glass 
  with 
  end 
  windows 
  of 
  plate 
  

   glass 
  were 
  readily 
  united 
  at 
  a 
  temperature 
  near 
  4*70° 
  C. 
  For 
  

   obvious 
  reasons, 
  success 
  was 
  not 
  attained 
  in 
  attempting 
  to 
  unify 
  

   an 
  object-glass 
  the 
  component 
  parts 
  of 
  which 
  were 
  made 
  of 
  

   ordinary 
  crown 
  and 
  flint 
  glass. 
  Although 
  the 
  problem 
  of 
  con- 
  

   structing 
  ultra-violet 
  absorption 
  cells 
  of 
  fused 
  silica 
  has 
  not 
  been 
  

   completely 
  solved, 
  the 
  results 
  thus 
  far 
  obtained 
  give 
  promise 
  of 
  

   ultimate 
  success. 
  — 
  Phil. 
  Mag., 
  xxxiii, 
  p. 
  276, 
  March, 
  1917. 
  

  

  h. 
  s. 
  F. 
  

  

  6. 
  The 
  Flame 
  Spectrum 
  of 
  Iron. 
  — 
  A 
  promising 
  method 
  for 
  

   differentiating 
  and 
  classifying 
  the 
  lines 
  of 
  complicated 
  spectra 
  has 
  

   been 
  recently 
  developed, 
  and 
  applied 
  to 
  the 
  case 
  of 
  iron, 
  by 
  G. 
  A. 
  

   Hemsalech. 
  The 
  special 
  features 
  of 
  the 
  apparatus 
  employed 
  

   consist 
  in 
  the 
  "electric 
  sprayer" 
  and 
  the 
  gas 
  burners. 
  

  

  The 
  most 
  essential 
  parts 
  of 
  the 
  sprayer 
  may 
  be 
  described 
  as 
  

   follows 
  : 
  An 
  inverted 
  bell-jar 
  (height 
  10*5 
  in., 
  diameter 
  5 
  in.) 
  is 
  

   closed 
  at 
  the 
  lower, 
  narrow 
  end 
  by 
  a 
  rubber 
  stopper 
  and 
  at 
  the 
  

   upper, 
  wide 
  end 
  by 
  a 
  flanged 
  wooden 
  disk. 
  A 
  stout 
  wire, 
  which 
  

   passes 
  up 
  through 
  the 
  axis 
  of 
  the 
  stopper, 
  is 
  rigidly 
  attached 
  to 
  

   an 
  iron 
  electrode. 
  The 
  vertical 
  portion 
  of 
  an 
  L-shaped 
  glass 
  tube 
  

   also 
  passes 
  through 
  the 
  stopper. 
  The 
  outer 
  end 
  of 
  the 
  glass 
  tube 
  

   is 
  connected 
  to 
  an 
  adjustable 
  glass 
  reservoir 
  by 
  a 
  rubber 
  tube. 
  

   By 
  means 
  of 
  a 
  pinch-cock 
  the 
  liquid 
  (perchloride 
  of 
  iron) 
  is 
  

   allowed 
  to 
  flow 
  from 
  the 
  reservoir 
  into 
  the 
  bell-jar 
  until 
  its 
  free 
  

   surface 
  is 
  just 
  above 
  the 
  top 
  of 
  the 
  lower 
  electrode 
  mentioned 
  

   above. 
  The 
  upper 
  electrode, 
  likewise 
  of 
  iron, 
  passes 
  down 
  axially 
  

   through 
  the 
  wooden 
  cover, 
  its 
  lower 
  end 
  being 
  about 
  - 
  25 
  in. 
  

   above 
  the 
  liquid. 
  The 
  iron 
  wire 
  is 
  insulated 
  by 
  a 
  glass 
  tube 
  

   throughout 
  all 
  of 
  its 
  length 
  within 
  the 
  bell-jar 
  except 
  the 
  lowest 
  

   inch 
  which 
  is, 
  of 
  course, 
  left 
  bare. 
  The 
  inlet 
  tube 
  for 
  various 
  

   gases 
  (air, 
  oxygen, 
  etc.) 
  extends 
  down 
  through 
  the 
  wooden 
  lid 
  to 
  

   within 
  a 
  short 
  distance 
  above 
  the 
  free-surface 
  of 
  the 
  liquid 
  in 
  the 
  

   jar. 
  The 
  outlet 
  tube 
  is 
  flared 
  conically 
  at 
  the 
  end 
  which 
  projects 
  

   only 
  a 
  short 
  distance 
  below 
  the 
  under 
  surface 
  of 
  the 
  wooden 
  

   cover. 
  When 
  a 
  condensed 
  spark 
  (20,000-30,000 
  volts) 
  passes 
  

   between 
  the 
  electrodes 
  the 
  material 
  under 
  investigation 
  is 
  broken 
  

   up 
  into 
  particles 
  of 
  ultra-microscopic 
  dimensions 
  which 
  are 
  

   carried 
  to 
  the 
  burner 
  by 
  the 
  current 
  of 
  gas. 
  Details 
  of 
  the 
  re- 
  

   fining 
  collectors 
  for 
  keeping 
  back 
  the 
  coarser 
  particles, 
  and 
  of 
  the 
  

   method 
  of 
  mixing 
  the 
  spray-carrying 
  gas 
  with 
  illuminating 
  gas 
  

   or 
  hydrogen 
  will 
  be 
  omitted. 
  

  

  Hemsalech 
  states 
  that 
  the 
  burners 
  form 
  the 
  most 
  important 
  

   item 
  in 
  the 
  instrumental 
  equipment. 
  Their 
  tops 
  were 
  prepared 
  

  

  