﻿126 
  C. 
  Bar 
  us 
  — 
  Continuity 
  of 
  Solid 
  and 
  Liquid. 
  

  

  lene 
  and 
  some 
  others, 
  1 
  thus 
  obtained 
  satisfactory 
  results.* 
  

   Such 
  work 
  is, 
  however, 
  limited 
  to 
  relatively 
  low 
  pressures 
  (600 
  

   to 
  800 
  atm.) 
  ; 
  it 
  does 
  not 
  admit 
  of 
  sufficient 
  correction 
  for 
  the 
  

   volume 
  changes 
  of 
  the 
  glass, 
  and 
  from 
  the 
  small 
  quantity 
  of 
  

   substance 
  examined, 
  and 
  the 
  relatively 
  frequent 
  occurrence 
  of 
  

   nuclear 
  condensation, 
  volume 
  lags 
  are 
  often 
  obscured. 
  Hence 
  

   the 
  definition 
  which 
  I 
  was 
  inclined 
  to 
  adopt 
  after 
  making 
  

   these 
  experiments, 
  viz 
  : 
  that 
  a 
  pressure 
  which 
  when 
  acting 
  

   isothermally 
  for 
  an 
  infinite 
  time 
  will 
  just 
  solidify 
  the 
  liquid 
  

   and 
  will 
  just 
  liquify 
  the 
  solid, 
  stands 
  to 
  the 
  given 
  temperature 
  

   in 
  the 
  relation 
  of 
  melting 
  point 
  and 
  pressure, 
  is 
  not 
  in 
  accord- 
  

   ance 
  with 
  facts, 
  f 
  

  

  In 
  a 
  second 
  method;); 
  I 
  endeavored 
  to 
  ascertain 
  the 
  positions 
  

   of 
  the 
  characteristic 
  specific 
  volumes 
  by 
  passing 
  current 
  out 
  of 
  

   the 
  mercury 
  index 
  through 
  the 
  hot 
  w 
  T 
  alls 
  of 
  the 
  thin 
  glass 
  tube 
  

   which 
  contained 
  contiguous 
  columns 
  of 
  both 
  the 
  substance 
  and 
  

   the 
  mercury. 
  Supposing 
  the 
  tube 
  surrounded 
  by 
  a 
  liquid 
  

   conductor 
  transmitting 
  pressure, 
  the 
  changes 
  of 
  resistance 
  of 
  

   the 
  arrangement 
  indicate 
  the 
  motion 
  of 
  the 
  index 
  and 
  hence 
  

   the 
  degree 
  of 
  compression 
  produced. 
  Here, 
  however, 
  a 
  new 
  

   and 
  unexpected 
  annoyance 
  was 
  encountered, 
  inasmuch 
  as 
  both 
  

   the 
  medium 
  of 
  oil 
  contained 
  in 
  the 
  piezometer 
  and 
  the 
  glass 
  

   possess 
  seriously 
  large 
  pressure 
  coefficients^ 
  Moreover 
  it 
  is 
  

   only 
  with 
  great 
  difficulty 
  that 
  the 
  perfect 
  insulation 
  of 
  an 
  

   apparatus, 
  in 
  which 
  water 
  jackets 
  form 
  an 
  essential 
  part, 
  can 
  

   be 
  maintained. 
  I 
  therefore 
  abandoned 
  the 
  work. 
  

  

  In 
  a 
  third 
  method 
  similar 
  to 
  the 
  preceding, 
  I 
  expressed 
  the 
  

   motion 
  of 
  the 
  mercury 
  thread 
  or 
  index 
  in 
  terms 
  of 
  the 
  resist- 
  

   ance 
  of 
  a 
  very 
  fine 
  platinum 
  wire, 
  passing 
  through 
  the 
  axis 
  of 
  

   the 
  tube. 
  Successive 
  intercepts 
  thus 
  indicated 
  the 
  changes 
  of 
  

   volume 
  to 
  be 
  observed. 
  This 
  method 
  gave 
  good 
  indications 
  of 
  

   the 
  pressure 
  position 
  of 
  the 
  melting 
  points 
  of 
  the 
  sample. 
  It 
  

   failed, 
  however, 
  to 
  give 
  serviceable 
  values 
  for 
  the 
  fiuid 
  volume 
  

   changes. 
  I 
  found 
  on 
  trial 
  that 
  the 
  contacts 
  in 
  such 
  a 
  case 
  are 
  

   essentially 
  loose, 
  and 
  that 
  thermocurrents 
  can 
  only 
  with 
  diffi- 
  

   culty 
  be 
  eliminated 
  or 
  allowed 
  for, 
  seeing 
  that 
  the 
  successive 
  

   isothermal 
  temperatures 
  are 
  to 
  be 
  considerably 
  above 
  the 
  at- 
  

   mospheric 
  temperature. 
  

  

  Finally 
  all 
  the 
  methods 
  here 
  described 
  must 
  necessarily 
  fail 
  

   after 
  the 
  substance 
  has 
  been 
  solidified 
  ; 
  for 
  in 
  this 
  case 
  the 
  

   thread 
  or 
  index 
  is 
  split 
  up 
  and 
  forced 
  into 
  the 
  interstices 
  of 
  the 
  

   solid 
  material. 
  Thus 
  it 
  is 
  manifestly 
  impossible 
  to 
  retain 
  the 
  

  

  * 
  Cf. 
  this 
  Journal, 
  xxxviii, 
  p. 
  408, 
  1889. 
  

  

  f 
  A 
  considerable 
  number 
  of 
  experiments 
  made 
  with 
  naphthalene 
  in 
  this 
  way 
  

   showed 
  the 
  melting 
  points 
  83*4°, 
  92*3°, 
  100°, 
  to 
  correspond 
  to 
  the 
  pressures 
  

   100 
  atm. 
  350 
  atm., 
  565 
  atm. 
  respectively. 
  Thus 
  the 
  factor 
  is 
  +*036° 
  C./ 
  atm. 
  § 
  27 
  

  

  ± 
  Phil. 
  Mag., 
  xxxi, 
  p. 
  14, 
  1891. 
  

  

  § 
  Ibid, 
  pp. 
  18 
  to 
  24, 
  et. 
  seq. 
  

  

  