﻿132 
  C. 
  Barns 
  — 
  Continuity 
  of 
  Solid 
  and 
  Liquid. 
  

  

  charge 
  at 
  82° 
  is 
  *552 
  cm 
  3 
  , 
  which 
  1 
  took 
  for 
  the 
  volume 
  at 
  the 
  

   normal 
  melting 
  point 
  (80°). 
  

  

  9. 
  Expansion 
  and 
  compressibility 
  of 
  envelopes. 
  — 
  The 
  plug 
  

   of 
  mercury 
  weighed 
  7*74 
  <?. 
  Its 
  volume 
  was 
  therefore 
  '571 
  cm 
  3 
  , 
  

   at 
  20°, 
  arid 
  its 
  mean 
  volume 
  between 
  60° 
  and 
  130° 
  (being 
  be- 
  

   tween 
  -575 
  and 
  *582) 
  sufficiently 
  near 
  *58 
  cm 
  3 
  . 
  

  

  Thus 
  the 
  volume 
  of 
  the 
  glass 
  tube 
  containing 
  both 
  the 
  

   charge 
  of 
  naphthalene 
  and 
  of 
  mercury, 
  was 
  113 
  cm 
  3 
  . 
  Its 
  

   expansion 
  per 
  degree 
  centigrade 
  '000028 
  cm 
  3 
  , 
  while 
  the 
  ex- 
  

   pansion 
  of 
  the 
  mercury 
  in 
  place 
  was 
  -000105 
  cm 
  3 
  , 
  per 
  de- 
  

   gree, 
  whence 
  the 
  apparent 
  expansion 
  '00007 
  cm 
  3 
  per 
  degree. 
  

   Therefore 
  if 
  in 
  place 
  of 
  the 
  fiducial 
  volume 
  '552 
  cm 
  3 
  (§ 
  8), 
  

   the 
  following 
  volumes 
  be 
  substituted, 
  viz 
  : 
  

  

  60° 
  -5565 
  cm. 
  3 
  100° 
  -5535 
  cm. 
  3 
  

  

  80° 
  -5550 
  120° 
  -5519 
  

  

  90° 
  -5542 
  130° 
  -5311 
  

  

  the 
  tube 
  may 
  be 
  treated 
  as 
  free 
  from 
  thermal 
  expansion. 
  Here 
  

   at 
  80°, 
  '555 
  appears 
  instead 
  of 
  '552, 
  to 
  allow 
  for 
  the 
  fiducial 
  

   volume 
  of 
  the 
  stem 
  M 
  (fig. 
  1), 
  as 
  will 
  be 
  shown 
  in 
  § 
  17. 
  

  

  Again 
  the 
  compression 
  of 
  the 
  1*13 
  cm. 
  3 
  of 
  glass, 
  and 
  the 
  

   *58 
  cm. 
  3 
  , 
  of 
  mercury 
  will 
  be 
  : 
  

  

  100 
  atm. 
  

  

  glass, 
  

  

  •00025 
  cm. 
  3 
  

  

  ; 
  mercury, 
  '00023 
  cm. 
  3 
  

  

  ; 
  diffe 
  

  

  rence, 
  

  

  •00002 
  cm 
  

  

  500 
  

  

  

  124 
  

  

  113 
  

  

  

  

  11 
  

  

  1000 
  

  

  

  249 
  

  

  226 
  

  

  

  

  23 
  

  

  1500 
  

  

  

  373 
  

  

  339 
  

  

  

  

  34 
  

  

  2000 
  

  

  

  491 
  

  

  452 
  

  

  

  

  45 
  

  

  Thus 
  the 
  corrections 
  which 
  would 
  individually 
  be 
  appreci- 
  

   able 
  (affecting 
  the 
  increments 
  say 
  3 
  per 
  cent) 
  are 
  differentially 
  

   negligible 
  (.3 
  per 
  cent) 
  where 
  they 
  fall 
  below 
  the 
  electrical 
  

   pressure 
  coefficient 
  of 
  the 
  zinc 
  sulphate 
  solution. 
  §14, 
  cf. 
  §3. 
  

  

  10. 
  Resistance 
  measurement. 
  — 
  Using 
  the 
  interrupter 
  and 
  

   telephone 
  (§6), 
  I 
  facilitated 
  audition 
  by 
  connecting 
  the 
  dia- 
  

   phragm 
  cup 
  with 
  a 
  graphophone 
  tube, 
  and 
  listening 
  with 
  both 
  

   ears. 
  The 
  resistances, 
  however, 
  were 
  rather 
  higher 
  than 
  con- 
  

   templated 
  in 
  Kohlrausch's 
  method, 
  when 
  an 
  ordinary 
  Bell 
  

   telephone 
  is 
  used. 
  Hence 
  the 
  measurements 
  particularly 
  near 
  

   and 
  in 
  the 
  solid 
  state 
  are 
  far 
  below 
  the 
  limit 
  of 
  attainable 
  

   accuracy. 
  I 
  shall 
  in 
  future 
  measurements 
  wind 
  a 
  telephone 
  

   specially 
  adapted 
  for 
  my 
  purposes, 
  and 
  endeavor 
  to 
  use 
  both 
  

   ends 
  of 
  the 
  magnet 
  to 
  actuate 
  diaphragms. 
  When 
  zinc 
  sul- 
  

   phate 
  is 
  enclosed 
  between 
  terminals 
  of 
  zinc, 
  continuous 
  cur- 
  

   rents 
  and 
  the 
  galvanometer 
  are 
  available. 
  In 
  this 
  way, 
  I 
  

   made 
  most 
  of 
  the 
  calibration 
  measurements. 
  Supposing 
  the 
  

   mercury 
  index 
  to 
  be 
  slightly 
  deadened 
  in 
  its 
  electronegative 
  

   qualities 
  by 
  zinc, 
  it 
  may 
  also 
  be 
  used 
  in 
  case 
  of 
  the 
  tube. 
  

  

  Should 
  the 
  measuring 
  thread 
  of 
  mercury 
  gk, 
  figure 
  1, 
  break 
  

   into 
  parts 
  alternating 
  with 
  threads 
  of 
  zinc 
  sulphate 
  (a 
  possi- 
  

  

  