﻿C. 
  Barus 
  — 
  Continuity 
  of 
  Solid 
  and 
  Liquid. 
  133 
  

  

  bility 
  when 
  the 
  thread 
  is 
  worked 
  up 
  and 
  down 
  many 
  hundred 
  

   times, 
  particularly 
  in 
  view 
  of 
  the 
  suddenness 
  of 
  solidification), 
  

   the 
  constants 
  of 
  reduction 
  are 
  not 
  thereby 
  necessarily 
  vitiated, 
  

   always 
  supposing 
  the 
  number 
  of 
  such 
  breaks 
  to 
  be 
  small. 
  The 
  

   shifting 
  of 
  coordinates 
  thus 
  produced 
  can 
  be 
  corrected 
  by 
  

   check- 
  work 
  at 
  a 
  given 
  temperature.* 
  Long 
  continued 
  passage 
  

   of 
  intermittent 
  currents, 
  charges 
  the 
  mercury 
  with 
  zinc, 
  but 
  

   solution 
  of 
  mercury 
  can 
  not 
  become 
  serious, 
  since 
  the 
  column 
  

   is 
  being 
  continually 
  washed 
  by 
  the 
  terminal 
  D. 
  Some 
  advan- 
  

   tage 
  would 
  be 
  gained 
  by 
  using 
  zinc 
  sulphate 
  in 
  the 
  strength 
  

   (1*286, 
  Kohlrausch) 
  which 
  corresponds 
  to 
  maximum 
  conduct- 
  

   ivity. 
  

  

  11. 
  Calibration. 
  — 
  The 
  tube 
  hk, 
  figure 
  1, 
  being 
  of 
  insuffi- 
  

   ciently 
  uniform 
  caliber, 
  volume 
  must 
  be 
  expressed 
  as 
  a 
  func- 
  

   tion 
  of 
  length. 
  This 
  I 
  did 
  by 
  weighing 
  threads 
  of 
  mercury, 
  

   whose 
  length 
  had 
  been 
  measured 
  in 
  successive 
  parts 
  of 
  the 
  

   tube, 
  obtaining 
  the 
  results 
  of 
  the 
  first 
  two 
  columns 
  of 
  table 
  1. 
  

   The 
  fiducial 
  zero 
  is 
  here 
  arbitraily 
  placed 
  2 
  cm 
  below 
  the 
  ring 
  

   66. 
  

  

  Similarly 
  the 
  resistance 
  of 
  the 
  filament 
  of 
  zinc 
  sulphate 
  hg 
  

   must 
  be 
  expressed 
  as 
  a 
  function 
  of 
  length, 
  referred 
  to 
  the 
  

   same 
  fiducial 
  zero, 
  at 
  some 
  convenient 
  atmospheric 
  temperature. 
  

   To 
  do 
  this, 
  I 
  drew 
  a 
  zinc 
  wire 
  down 
  to 
  a 
  diameter 
  slightly 
  

   below 
  the 
  caliber 
  of 
  the 
  tube. 
  Opening 
  the 
  bottom 
  of 
  AB, 
  

   and 
  closing 
  the 
  top 
  so 
  as 
  to 
  hold 
  the 
  terminal 
  D 
  firmly 
  in 
  posi- 
  

   tion, 
  I 
  inverted 
  the 
  tube 
  and 
  quite 
  filled 
  it 
  with 
  the 
  solution. 
  

   AB 
  was 
  then 
  placed 
  in 
  a 
  cold 
  water 
  bath, 
  with 
  the 
  terminal 
  a 
  

   insulated, 
  and 
  the 
  terminal 
  h 
  replaced 
  by 
  the 
  zinc 
  wire 
  referred 
  

  

  Table 
  1. 
  — 
  Volumes 
  per 
  unit 
  of 
  length. 
  Electrical 
  resistance 
  per 
  unit 
  of 
  length 
  

   6=11-8°. 
  Volume 
  per 
  unit 
  of 
  resistance 
  6=1*1-8°. 
  

  

  Length. 
  V 
  

  

  Dlurae. 
  

  

  Length. 
  

  

  Resistance. 
  

  

  Resistance. 
  

  

  Volume. 
  

  

  cm. 
  

  

  3-00 
  

  

  11-15 
  

  

  cm. 
  z 
  

   0491 
  

   1609 
  

  

  cm. 
  

  

  -06 
  

   2-13 
  

   4-75 
  

   7-96 
  

  

  12-06 
  

  

  ohms. 
  

   2720 
  

   5780 
  

   10190 
  

   1620.0 
  

   24340 
  

  

  ohms. 
  

  

  2800 
  

  

  5530 
  

  

  8850 
  

  

  12530 
  

  

  16270 
  

  

  20250 
  

  

  24250 
  

  

  28500 
  

  

  1 
  

  

  cm? 
  

   •0000 
  

   •0350 
  

  

  4-45 
  

  

  9-79 
  

  

  15-42 
  

  

  0715 
  

   1430 
  

   2145 
  

  

  •0640 
  

   •0920 
  

   •1190 
  

  

  3*30 
  

  

  7-20 
  

   11-40 
  

   15-60 
  

  

  0538 
  

   1076 
  

   1614 
  

   2152 
  

  

  1-38 
  

   3-43 
  

   6-18 
  

   9-00 
  

   11-49 
  

  

  4630 
  

   7920 
  

   12790 
  

   18220 
  

   23140 
  

  

  •1450 
  

   •1705 
  

   •1960 
  

  

  2-75 
  

   6-10 
  

   9-65 
  

   13-40 
  

  

  0470 
  

   0910 
  

   1410 
  

   1880 
  

  

  

  * 
  This 
  I 
  should 
  have 
  done 
  after 
  obtaining 
  Table 
  9, 
  §21 
  ; 
  but 
  the 
  full 
  details 
  of 
  

   manipulation 
  could 
  not 
  all 
  be 
  foreseen 
  at 
  the 
  outset. 
  

  

  