﻿Uhler 
  and 
  Patterson 
  — 
  Arc 
  Spectrum 
  of 
  Tellurium. 
  135 
  

  

  Art. 
  XY. 
  — 
  The 
  Arc 
  Spectrum 
  of 
  Tellurium 
  ; 
  by 
  H. 
  S. 
  

   Uhler 
  and 
  P. 
  A. 
  Patterson. 
  

  

  The 
  object 
  of 
  the 
  present 
  paper 
  is 
  to 
  give 
  an 
  account 
  of 
  the 
  

   results 
  of 
  our 
  experimentation 
  upon 
  the 
  arc 
  spectrum 
  of 
  

   tellurium 
  and 
  to 
  place 
  on 
  record 
  the 
  wave-lengths 
  of 
  the 
  arc 
  

   lines 
  on 
  the 
  basis 
  of 
  the 
  international 
  system. 
  The 
  attention 
  

   of 
  the 
  senior 
  author 
  was 
  directed 
  to 
  the 
  interesting 
  and 
  appar- 
  

   ently 
  anomalous 
  behavior 
  of 
  tellurium 
  with 
  respect 
  to 
  the 
  

   JMendeleefT 
  table 
  during 
  the 
  winter 
  of 
  1910-11 
  by 
  Professor 
  

   Philip 
  E. 
  Browning 
  at 
  the 
  time 
  when 
  Doctor 
  William 
  P. 
  

   Flint 
  was 
  working, 
  in 
  the 
  Kent 
  Chemical 
  Laboratory, 
  on 
  the 
  

   problem 
  of 
  the 
  complexity 
  and 
  atomic 
  weight 
  of 
  tellurium. 
  

   At 
  that 
  time 
  the 
  primary 
  object 
  in 
  the 
  spectroscopic 
  work 
  was 
  

   to 
  test 
  the 
  purity 
  of 
  Flint's 
  material. 
  In 
  order 
  to 
  avoid 
  gas 
  

   lines 
  and 
  to 
  obtain 
  the 
  spectral 
  lines 
  as 
  sharp 
  as 
  possible 
  the 
  

   electric 
  arc 
  was 
  used 
  instead 
  of 
  the 
  spark. 
  Also 
  to 
  save 
  the 
  

   metal 
  and 
  to 
  prevent 
  oxidation 
  the 
  arc 
  was 
  formed 
  in 
  a 
  specially 
  

   constructed 
  brass 
  cylinder 
  through 
  which 
  a 
  current 
  of 
  carbon 
  

   dioxide 
  gas 
  was 
  kept 
  flowing. 
  The 
  grating 
  then 
  employed 
  had 
  

   a 
  radius 
  of 
  curvature 
  of 
  about 
  ten 
  feet, 
  14,436 
  lines 
  per 
  inch, 
  

   and 
  it 
  was 
  ruled 
  by 
  Schneider 
  on 
  one 
  of 
  Rowland's 
  engines. 
  

   Since 
  the 
  mass 
  of 
  each 
  of 
  Flint's 
  most 
  important 
  by-products 
  

   was 
  small, 
  a 
  little 
  preliminary 
  work 
  showed 
  that 
  the 
  spectro- 
  

   graph 
  was 
  too 
  large 
  for 
  the 
  object 
  then 
  in 
  view. 
  Consequently 
  

   the 
  problem 
  of 
  testing 
  spectroscopically 
  the 
  composition 
  of 
  

   these 
  by-products 
  was 
  deferred 
  until 
  more 
  suitable 
  apparatus 
  

   could 
  be 
  obtained. 
  Nevertheless, 
  it 
  may 
  be 
  stated 
  that 
  the 
  arc 
  

   between 
  comparatively 
  pure 
  electrodes 
  of 
  metallic 
  tellurium 
  

   could 
  not 
  be 
  maintained 
  continuously 
  at 
  about 
  110 
  volts 
  in 
  

   hydrogen, 
  or 
  in 
  carbon 
  dioxide, 
  or 
  in 
  air. 
  In 
  fact, 
  the 
  carbon 
  

   dioxide 
  seemed 
  to 
  be 
  partly 
  reduced 
  because 
  the 
  spectrograms 
  

   showed 
  all 
  the 
  strong 
  lines 
  of 
  carbon 
  and 
  a 
  black 
  deposit, 
  

   which 
  may 
  have 
  been 
  finely 
  divided 
  graphite, 
  was 
  formed 
  on 
  

   the 
  electrodes. 
  Especial 
  care 
  was 
  not 
  taken 
  to 
  purify 
  the 
  car- 
  

   bon 
  dioxide 
  as 
  was 
  made 
  evident 
  by 
  the 
  presence 
  on 
  the 
  nega- 
  

   tives 
  of 
  the 
  band 
  at 
  X3590, 
  which 
  is 
  usually 
  ascribed 
  to 
  

   cyanogen. 
  

  

  Since 
  the 
  time 
  mentioned 
  above 
  we 
  have 
  been 
  so 
  fortunate 
  

   as 
  to 
  obtain 
  two 
  concave 
  gratings 
  ruled 
  by 
  Professor 
  John 
  A. 
  

   Anderson 
  on 
  Rowland's 
  remodelled 
  engines. 
  The 
  smaller 
  

   grating 
  is 
  the 
  best 
  we 
  have 
  ever 
  seen 
  and 
  the 
  larger 
  one 
  is 
  of 
  

   the 
  highest 
  grade. 
  The 
  former 
  has 
  a 
  radius 
  of 
  curvature 
  of 
  

   one 
  meter 
  and 
  18,159 
  lines 
  in 
  the 
  space 
  of 
  4'60 
  cms 
  . 
  It 
  is 
  

   mounted 
  in 
  essentially 
  the 
  same 
  manner 
  as 
  was 
  the 
  grating 
  set 
  

  

  