﻿31. 
  I. 
  Pupin 
  — 
  Automatic 
  Mercury 
  Vacuum 
  Pump. 
  19 
  

  

  Art. 
  II. 
  — 
  An 
  Automatic 
  Mercury 
  Vacuum 
  Pump 
  • 
  by 
  

   M. 
  I. 
  Pupin, 
  Ph.D., 
  Columbia 
  College. 
  

  

  The 
  pump 
  which 
  forms 
  the 
  subject 
  of 
  the 
  following 
  descrip- 
  

   tion 
  is 
  a 
  combination 
  of 
  two 
  distinct 
  forms 
  of 
  apparatus. 
  First, 
  

   a 
  suction-pump 
  capable 
  of 
  raising 
  mercury 
  to 
  practically 
  any 
  

   height 
  and 
  secondly, 
  an 
  ordinary 
  Sprengel 
  pump. 
  The 
  part 
  

  

  connecting 
  the 
  two 
  is 
  a 
  syphon 
  

   barometer, 
  properly 
  disposed 
  with 
  

   respect 
  to 
  the 
  two 
  parts 
  which 
  it 
  

   connects. 
  

  

  Referring 
  now 
  to 
  the 
  diagram 
  I 
  

   shall 
  describe 
  each 
  part 
  separately 
  

   and 
  shall 
  then 
  explain 
  the 
  modus 
  

   operandi 
  of 
  the 
  combination. 
  

  

  1. 
  The 
  Suction 
  Pump. 
  

  

  It 
  consists 
  of 
  the 
  reservoir 
  A 
  to 
  

   which 
  are 
  joined 
  the 
  short 
  tube 
  n 
  

   and 
  the 
  tube 
  t 
  v 
  m 
  which 
  I 
  shall 
  call 
  

   the 
  suction 
  tube. 
  A 
  short 
  branch 
  

   tube 
  vw 
  is 
  connected 
  by 
  a 
  rubber 
  

   tube 
  w 
  u 
  to 
  the 
  wide 
  tube 
  u 
  x. 
  This 
  

   wide 
  tube 
  I 
  shall 
  call 
  the 
  valve 
  tube. 
  

   The 
  suction 
  tube 
  and 
  the 
  valve 
  tube 
  

   dip 
  in 
  two 
  separate 
  mercury 
  vessels 
  

   E 
  and 
  D 
  which 
  are 
  provided 
  with 
  

   specially 
  constructed 
  glass 
  dishes 
  1, 
  

   2, 
  3, 
  4 
  containing 
  concentrated 
  sul- 
  

   phuric 
  acid 
  for 
  drying 
  purposes. 
  

   The 
  two 
  vessels 
  are 
  connected 
  to 
  

   each 
  other 
  by 
  means 
  of 
  a 
  rubber 
  

   tube. 
  A 
  part 
  of 
  the 
  suction 
  tube 
  

   a 
  b 
  about 
  20 
  cm 
  long 
  has 
  a 
  cross-sec- 
  

   tion 
  one-half 
  as 
  large 
  as 
  that 
  of 
  the 
  

   rest 
  of 
  the 
  tube. 
  

  

  2. 
  The 
  Sprengel 
  Pump. 
  

  

  It 
  is 
  of 
  the 
  ordinary 
  type 
  and 
  consists 
  of 
  the 
  reservoir 
  B 
  

   from 
  which 
  the 
  mercury 
  drops 
  into 
  a 
  long 
  tube^?^, 
  the 
  tube 
  of 
  

   descent. 
  This 
  tube 
  may 
  be 
  given 
  any 
  convenient 
  length 
  ; 
  160 
  cm 
  

   will 
  be 
  found 
  sufficient 
  for 
  rapid 
  working. 
  The 
  tube 
  of 
  

   descent 
  carries 
  a 
  lateral 
  extension 
  which 
  is 
  connected 
  to 
  the 
  

   reservoir 
  .B 
  by 
  means 
  of 
  the 
  tube 
  g 
  h 
  i. 
  The 
  object 
  of 
  this 
  

  

  