﻿Dr. 
  C. 
  Cbree's 
  Notes 
  on 
  Thermometry. 
  301 
  

  

  Table 
  VIII. 
  

  

  Temperature 
  

   centigrade. 
  

  

  Distilled 
  water-ice, 
  tree 
  from 
  air 
  (P'OOOO 
  

  

  Distilled 
  water-ice 
  —0 
  0014 
  

  

  Natural 
  ice 
  mixed 
  with 
  distilled 
  water 
  — 
  0'0017 
  

  

  Natural 
  ice 
  moist 
  —0-0003 
  

  

  Natural 
  ice, 
  finely 
  divided, 
  dry 
  — 
  0-0035 
  

  

  Snow, 
  dry 
  -00060 
  

  

  Snow, 
  moistened 
  with 
  distilled 
  water 
  — 
  - 
  0004 
  

  

  Snow 
  moistened, 
  after 
  water 
  flowed 
  out 
  — 
  0'0038 
  

  

  These 
  are 
  to 
  be 
  regarded 
  rather 
  as 
  indications 
  of 
  the 
  order 
  

   of 
  probable 
  differences 
  under 
  ordinary 
  conditions 
  than 
  as 
  

   rigid 
  physical 
  data. 
  Thus 
  Marek, 
  whose 
  results 
  Guillaume 
  

   also 
  quotes 
  *, 
  got 
  for 
  dry 
  artificial 
  ice 
  — 
  o, 
  0519 
  or 
  — 
  o, 
  0919, 
  

   according 
  as 
  it 
  was 
  finely 
  divided 
  or 
  only 
  pounded. 
  

  

  When 
  ice 
  is 
  dry, 
  its 
  temperature 
  may 
  in 
  reality 
  be 
  very 
  

   much 
  below 
  the 
  freezing-point. 
  Of 
  course 
  under 
  ordinary 
  

   experimental 
  conditions 
  the 
  ice 
  is 
  exposed 
  to 
  a 
  temperature 
  

   over 
  0°, 
  and 
  its 
  surface 
  is 
  usually 
  moist. 
  The 
  tendency 
  for 
  

   the 
  ice 
  in 
  the 
  centre 
  of 
  large 
  blocks 
  to 
  be 
  at 
  a 
  lower 
  tem- 
  

   perature 
  than 
  0° 
  C. 
  has 
  been 
  noticed 
  at 
  the 
  Reichsanstalt 
  f, 
  

   where 
  it 
  is 
  the 
  practice 
  to 
  employ 
  artificial 
  ice 
  from 
  distilled 
  

   water. 
  

  

  In 
  making 
  artificial 
  ice, 
  the 
  purity 
  of 
  the 
  water 
  seems 
  of 
  

   some 
  importance, 
  ice 
  from 
  tap 
  or 
  cistern- 
  water 
  giving 
  

   freezing-points 
  too 
  low 
  by 
  from 
  0°'002 
  C. 
  to 
  0°'003 
  C. 
  f 
  

  

  To 
  obtain 
  results 
  agreeing 
  to 
  o, 
  001 
  C. 
  a 
  very 
  uniform 
  

   procedure 
  must 
  be 
  followed, 
  and 
  it 
  is 
  quite 
  conceivable 
  that 
  

   the 
  adoption 
  of 
  different 
  procedures 
  at 
  different 
  places 
  might 
  

   lead 
  to 
  slightly 
  different 
  scales 
  of 
  temperature 
  J 
  . 
  

  

  One 
  disturbing 
  agent, 
  to 
  which 
  attention 
  may 
  be 
  called, 
  is 
  

   conduction 
  of 
  heat 
  down 
  the 
  thermometer 
  stem. 
  Though 
  

   specially 
  to 
  be 
  feared 
  in 
  depressed-zero 
  readings 
  following 
  

   high 
  temperatures, 
  its 
  absence 
  can 
  hardly, 
  perhaps, 
  be 
  safely 
  

   assumed 
  in 
  ordinary 
  fixed-zero 
  determinations, 
  especially 
  in 
  a 
  

   hot 
  room. 
  

  

  In 
  dealing 
  with 
  toluene 
  or 
  other 
  spirit-thermometers, 
  in 
  

   which 
  the 
  liquid 
  wets 
  the 
  tube, 
  the 
  depressed 
  zero 
  method 
  

   has 
  been 
  found 
  impracticable 
  at 
  the 
  Bureau 
  International 
  §, 
  

  

  * 
  Lcc. 
  cit. 
  p. 
  118. 
  

  

  t 
  Wiss. 
  Abhandl. 
  vol. 
  i. 
  p. 
  83. 
  

  

  X 
  Cf. 
  Comptes 
  Rendus 
  . 
  . 
  . 
  de 
  la 
  deuxieme 
  Conference 
  general 
  des 
  Poids 
  

   et 
  Mesures, 
  Paris, 
  1896, 
  pp. 
  125 
  and 
  133. 
  

  

  § 
  See 
  their 
  pamphlet, 
  Mesures 
  des 
  basses 
  Temperatures, 
  Paris, 
  1893 
  , 
  

   p. 
  4. 
  

  

  Phik 
  Mag. 
  S. 
  5. 
  Vol. 
  45. 
  No. 
  275. 
  April 
  1898. 
  Y 
  

  

  