﻿Determination 
  of 
  Potassium 
  Spectroscopically. 
  449 
  

  

  while 
  withdrawing 
  it. 
  How 
  closely 
  the 
  capacity 
  of 
  such 
  coils 
  

   may 
  be 
  adjusted, 
  and 
  how 
  uniformly 
  they 
  may 
  be 
  filled 
  is 
  

   shown 
  in 
  the 
  figures 
  of 
  the 
  accompanying 
  record. 
  

  

  I. 
  II. 
  III. 
  IT. 
  T. 
  VI. 
  

  

  grm. 
  grin, 
  grin, 
  grin, 
  grm. 
  grm. 
  

  

  Weight 
  of 
  filled 
  coil 
  01996 
  0-2780 
  0-2794 
  02844 
  0-3572 
  3296 
  

  

  ■ 
  0-1996 
  02780 
  0'2794 
  02845 
  0-3571 
  0-3296 
  

  

  " 
  0-1996 
  0-2780 
  0-2794 
  02844 
  0-3572 
  0*3298 
  

  

  " 
  " 
  0-1996 
  0-2780 
  0-2794 
  02845 
  0-3571 
  0*3298 
  

  

  " 
  01996 
  0-2781 
  0-2794 
  2844 
  0-3571 
  03296 
  

  

  '• 
  empty 
  coil 
  0-1986 
  0-2760 
  02764 
  0-2804 
  0.3521 
  0-3100 
  

  

  ■■ 
  contents 
  (mean) 
  0*0010 
  00202 
  0-0030 
  0-00404 
  000504 
  0-01968 
  

  

  It 
  is 
  plain 
  that 
  we 
  have 
  in 
  these 
  coils 
  simple 
  means 
  of 
  taking 
  

   up 
  known 
  amounts 
  of 
  material 
  in 
  solution 
  ; 
  and 
  by 
  gentle 
  

   heating 
  the 
  liquid 
  may 
  be 
  evaporated 
  and 
  the 
  solid 
  material 
  left 
  

   thinly 
  and 
  uniformly 
  spread, 
  not 
  easily 
  detachable 
  and 
  so 
  in 
  con- 
  

   dition 
  to 
  be 
  acted 
  upon 
  with 
  effect 
  when 
  brought 
  to 
  the 
  flame. 
  

   The 
  evaporation 
  may 
  be 
  conducted 
  with 
  little 
  danger 
  of 
  loss 
  

   of 
  material 
  by 
  holding 
  the 
  handle 
  of 
  the 
  coil 
  across 
  the 
  flame 
  

   with 
  the 
  coil 
  proper 
  at 
  a 
  safe 
  distance 
  outside 
  ; 
  but 
  we 
  have 
  

   generally, 
  and 
  preferably, 
  used 
  a 
  hot 
  radiator 
  over 
  which 
  the 
  

   coils 
  are 
  exposed, 
  the 
  handles 
  resting 
  upon 
  a 
  flat 
  asbestos 
  ring. 
  

   The 
  burner 
  which 
  we 
  haTe 
  used 
  in 
  heating 
  the 
  coils 
  before 
  

   the 
  spectroscope 
  is 
  of 
  the 
  Muencke 
  pattern 
  anci 
  gives 
  a 
  power- 
  

   ful 
  flame 
  3 
  cm. 
  wide 
  at 
  its 
  base. 
  We 
  have 
  generally 
  adjusted 
  

   the 
  flame 
  to 
  a 
  height 
  of 
  20 
  cm., 
  and 
  have 
  introduced 
  the 
  coil, 
  

   after 
  thorough 
  drying, 
  just 
  within 
  the 
  outer 
  mantle, 
  on 
  the 
  

   side 
  next 
  the 
  spectroscope, 
  with 
  the 
  axis 
  transverse 
  to 
  the 
  slit 
  

   of 
  the 
  spectroscope 
  and 
  the 
  handle 
  across 
  the 
  body 
  of 
  the 
  

   flame. 
  In 
  cleaning 
  the 
  coils 
  we 
  have 
  found 
  it 
  convenient 
  to 
  

   heat 
  them 
  in 
  the 
  flame 
  of 
  an 
  Argand 
  burner 
  of 
  the 
  Fletcher 
  

   pattern, 
  beneath 
  which 
  is 
  burned, 
  in 
  a 
  small 
  lamp, 
  alcohol 
  con- 
  

   taining 
  about 
  a 
  twentieth 
  of 
  its 
  volume 
  of 
  chloroform. 
  The 
  

   products 
  of 
  combustion 
  of 
  the 
  alcohol 
  and 
  chloroform 
  are 
  con- 
  

   veyed 
  to 
  the 
  interior 
  of 
  the 
  flame 
  above 
  by 
  a 
  glass 
  funnel 
  

   fitted 
  by 
  a 
  cork 
  to 
  the 
  tube 
  of 
  the 
  Argand 
  burner. 
  This 
  

   arrangement 
  of 
  apparatus 
  gives 
  a 
  hot 
  colorless 
  flame 
  through 
  

   which 
  hydrochloric 
  acid 
  is 
  constantly 
  diffused 
  in 
  condition 
  to 
  

   clean 
  the 
  wires 
  completely 
  and 
  without 
  attention. 
  The 
  spec- 
  

   troscope 
  which 
  we 
  have 
  employed 
  is 
  a 
  well-made 
  single 
  prism 
  

   instrument 
  provided 
  with 
  a 
  scale, 
  and 
  a 
  movable 
  observing 
  

   telescope 
  so 
  that 
  different 
  portions 
  of 
  the 
  spectrum 
  may 
  be 
  

   viewed 
  or 
  cut 
  off 
  at 
  will. 
  The 
  slit 
  is 
  adjustable, 
  but 
  for 
  meas- 
  

   uring 
  its 
  width 
  we 
  have 
  been 
  obliged 
  to 
  have 
  recourse 
  to 
  the 
  

   device 
  of 
  closing 
  it 
  upon 
  wires 
  of 
  known 
  gauge. 
  Our 
  work 
  

   has 
  been 
  done 
  in 
  the 
  ordinary 
  diffused 
  light 
  of 
  the 
  laboratory, 
  

   care 
  having 
  been 
  taken 
  to 
  cut 
  off 
  from 
  the 
  room 
  direct 
  sun- 
  

   light 
  only 
  ; 
  but 
  in 
  observing 
  it 
  has 
  been 
  our 
  custom 
  to 
  shield 
  

   the 
  eye 
  in 
  use 
  as 
  completely 
  as 
  possible 
  with 
  the 
  hand 
  or 
  with 
  

  

  