﻿W. 
  P. 
  White 
  — 
  Specific 
  Heat 
  Determination. 
  49 
  

  

  across 
  the 
  terminals 
  after 
  the 
  wire 
  was 
  melted. 
  9 
  The 
  

   difficulty 
  could 
  doubtless 
  have 
  been 
  overcome 
  by 
  making 
  

   the 
  current 
  fuse 
  a 
  length 
  of 
  copper 
  wire 
  outside 
  the 
  fur- 
  

   nace 
  at 
  the 
  same 
  time 
  as 
  the 
  supporting 
  wire 
  inside. 
  It 
  

   was 
  preferred, 
  however, 
  to 
  avoid 
  the 
  loss 
  of 
  time 
  10 
  and 
  

   the 
  expense 
  involved 
  in 
  manipulating 
  and 
  using 
  up 
  the 
  

   platinum 
  wire, 
  and 
  even 
  more 
  to 
  get 
  rid 
  of 
  the 
  effect 
  

   on 
  temperature 
  distribution 
  produced 
  by 
  the 
  pedestal 
  

   which 
  was 
  needed, 
  when 
  the 
  platinum 
  wires 
  were 
  used, 
  

   to 
  support 
  the 
  container 
  and 
  charge 
  during 
  the 
  long 
  

   heating. 
  A 
  mechanical 
  drop 
  was 
  therefore 
  installed, 
  

   shown 
  in 
  iig. 
  3. 
  It 
  was 
  made 
  of 
  Marquardt 
  composi- 
  

   tion, 
  which 
  we 
  had 
  in 
  the 
  form 
  of 
  tubes 
  and 
  plates. 
  

   Slots 
  were 
  cut 
  in 
  the 
  right-hand 
  tube 
  with 
  a 
  dentist's 
  

   grinding 
  wheel, 
  for 
  the 
  fiat 
  latch, 
  L, 
  to 
  move 
  in. 
  The 
  

   two 
  tubes 
  were 
  held 
  together 
  by 
  platinum 
  wire. 
  A 
  stout 
  

   platinum 
  wire 
  (about 
  1-2 
  mm.) 
  pulled 
  up 
  at 
  W 
  to 
  release 
  

   the 
  container, 
  and 
  was 
  operated 
  automatically 
  as 
  the 
  

   wooden 
  swinging 
  shield 
  under 
  the 
  furnace 
  was 
  swung 
  to 
  

   one 
  side. 
  The 
  latch 
  worked 
  at 
  1500°, 
  stood 
  all 
  the 
  high 
  

   temperature 
  work, 
  including 
  30 
  hours 
  at 
  1400°, 
  and 
  was 
  

   regularly 
  withdrawn 
  from 
  the 
  furnace 
  at 
  900°, 
  without 
  

   perceptible 
  alteration. 
  (The 
  work 
  above 
  900° 
  was 
  so 
  

   arranged 
  that 
  the 
  furnace 
  could 
  be 
  allowed 
  to 
  cool 
  before 
  

   it 
  was 
  necessary 
  to 
  withdraw 
  the 
  dropping 
  mechanism.) 
  

   It 
  gave 
  many 
  defective 
  drops, 
  but 
  these 
  were 
  mainly 
  due 
  

   to 
  two 
  things: 
  (1) 
  insufficient 
  rigidity 
  of 
  the 
  supports 
  

   combined 
  with 
  a 
  too 
  expeditious 
  swing 
  of 
  the 
  wooden 
  

   shield; 
  (2) 
  using 
  a 
  container 
  whose 
  diameter 
  was 
  too 
  

   near 
  that 
  of 
  the 
  furnace 
  tube. 
  As 
  the 
  work 
  progressed, 
  

   defective 
  drops 
  became 
  less 
  frequent. 
  There 
  is 
  no 
  

   doubt, 
  however, 
  that 
  with 
  a 
  little 
  care 
  the 
  electric 
  fusion 
  

   could 
  be 
  made 
  to 
  give 
  more 
  accurately 
  aimed 
  drops 
  than 
  

   could 
  be 
  obtained 
  with 
  the 
  latch. 
  The 
  relative 
  advan- 
  

   tages 
  of 
  the 
  fusion 
  method 
  are 
  of 
  course 
  greater 
  where 
  

   only 
  a 
  small 
  amount 
  of 
  work 
  is 
  in 
  view 
  (since 
  it 
  is 
  very 
  

   easy 
  to 
  install), 
  and 
  also 
  greater 
  at 
  lower 
  temperatures, 
  

   where 
  finer 
  wire 
  can 
  be 
  employed, 
  in 
  support 
  and 
  in 
  

   leads, 
  and 
  the 
  pedestal 
  can 
  often 
  be 
  omitted. 
  

  

  9 
  This 
  difficulty 
  was 
  discussed 
  in 
  Some 
  Calorimetric 
  Apparatus, 
  op. 
  cit., 
  

   page 
  677. 
  

  

  10 
  With 
  the 
  latch, 
  the 
  container 
  for 
  the 
  next 
  heating 
  could 
  be 
  placed 
  in 
  

   the 
  hot 
  furnace 
  during 
  the 
  first 
  6 
  minutes 
  of 
  the 
  calorimeter 
  determination 
  ; 
  

   the 
  wire 
  manipulation 
  took 
  too 
  long 
  to 
  be 
  sandwiched 
  in 
  in 
  this 
  way, 
  but 
  

   had 
  to 
  wait 
  each 
  time 
  till 
  the 
  calorimeter 
  work 
  was 
  done. 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Vol. 
  XL 
  VII 
  No. 
  277.— 
  January, 
  1919. 
  

  

  