﻿High 
  Temperatures. 
  

  

  179 
  

  

  ■^ 
  The 
  first 
  filling, 
  in 
  spite 
  of 
  the 
  care 
  exercised, 
  still 
  shows 
  

   signs 
  of 
  the 
  presence 
  of 
  hydrogen, 
  afterward 
  the 
  changes 
  in 
  

   ice 
  point 
  and 
  expansion 
  coefficient 
  become 
  noticeably 
  smaller, 
  

   though 
  the 
  latter 
  persists 
  in 
  a 
  tendency 
  to 
  increase 
  throughout. 
  

  

  The 
  mean 
  difference 
  between 
  the 
  observed 
  temperatures 
  and 
  

   those 
  obtained 
  from 
  the 
  carve 
  (Table 
  II) 
  is 
  ± 
  1'06°. 
  

  

  Zinc 
  hath. 
  — 
  In 
  order 
  to 
  continue 
  these 
  observations 
  to 
  a 
  

   higher 
  temperature 
  an 
  apparatus 
  for 
  boiling 
  zinc 
  was 
  provided. 
  

   The 
  boiling 
  kettle 
  proper 
  consisted 
  of 
  two 
  concentric 
  wrought 
  

   iron 
  cylinders, 
  M 
  and 
  N 
  (fig, 
  3), 
  welded 
  to 
  a 
  common 
  bottom. 
  

  

  

  (• 
  

  

  1/ 
  A- 
  - 
  A 
  .,; 
  

  

  / 
  '■-' 
  / 
  

  

  C 
  r 
  

  

  R 
  

  

  The 
  ring-shaped 
  space, 
  Z, 
  was 
  filled 
  with 
  zinc 
  while 
  the 
  inner 
  

   cylinder, 
  K, 
  contained 
  the 
  bulb 
  of 
  the 
  gas 
  thermometer 
  and 
  

   the 
  thermo-element, 
  the 
  latter 
  protected 
  as 
  before 
  by 
  a 
  porce- 
  

   lain 
  tube. 
  The 
  whole 
  was 
  closed 
  by 
  a 
  carefully 
  fitted 
  iron 
  

   cover 
  protected 
  as 
  much 
  as 
  possible 
  by 
  asbestos 
  and 
  fire-clay 
  

   against 
  loss 
  of 
  heat 
  by 
  conduction, 
  and 
  surrounded 
  by 
  a 
  jacket 
  

   of 
  fire-clay 
  pierced 
  by 
  a 
  tube 
  at 
  the 
  bottom 
  where 
  the 
  zinc 
  

   vapor 
  passed 
  off 
  and 
  the 
  six 
  blowpipes 
  furnishing 
  the 
  heat. 
  

   The 
  latter 
  were 
  arranged 
  in 
  a 
  spiral 
  and 
  directed 
  tangentially 
  

   against 
  the 
  zinc 
  kettle. 
  

  

  It 
  was 
  unfortunately 
  not 
  possible 
  to 
  place 
  the 
  thermometer 
  

   bulb 
  and 
  thermo-element 
  directly 
  in 
  the 
  zinc 
  vapor 
  on 
  account 
  

  

  